tag:blogger.com,1999:blog-28349727730431278072024-03-14T06:15:30.547+00:00Life On An Oxfordshire LawnAn amateur works out what lives in his garden.Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.comBlogger127125tag:blogger.com,1999:blog-2834972773043127807.post-44294750290121989422011-10-10T22:52:00.002+01:002011-10-10T22:57:05.855+01:00Two Noctuidae Moths - The Square Spot Rustic and The Setaceous Hebrew CharacterI am an amateur naturalist trying to discover everything living in my garden.<br />
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Some time ago I blogged (<a href="http://lifeonanoxfordlawn.blogspot.com/2009/03/oak-beauty-moth-biston-strateria.html">here</a> and <a href="http://lifeonanoxfordlawn.blogspot.com/2010/05/two-prominent-moths.html">here</a> for example) my homebuilt mothtrap. I set the trap out in my garden only a few times during 2009 and 2010. So great was the catch however that I'm still working through a backlog of photos of the species I caught (all critters were released alive after being photographed incidentally). <br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtPJsAPyNmFeKw1PMA44qDbFeK-DumxA8iCfgMSKqij7VZ-dRcf-nQ8fIhX6Cv_1EyYEgOqE6RlLKOca-EozLNG0pfwsKaVUGoIjBIaCOU0sqRvBCSoi76lo4PPcaECo3AdsyInEFVjMcm/s1600/square+spot+rustic+Xestia+xanthographa.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="266" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtPJsAPyNmFeKw1PMA44qDbFeK-DumxA8iCfgMSKqij7VZ-dRcf-nQ8fIhX6Cv_1EyYEgOqE6RlLKOca-EozLNG0pfwsKaVUGoIjBIaCOU0sqRvBCSoi76lo4PPcaECo3AdsyInEFVjMcm/s400/square+spot+rustic+Xestia+xanthographa.jpg" width="400" /></a></div>Two species from August 2009 I'm tolerably confident to have identified correctly (with the help of my copy of the <i>Concise Guide to the Moths of GB and Ireland, by Townsend, Waring and Lewington</i>) are a Square Spot Rustic (<i>Xestia xanthographa</i>) in photo 1 and a Setaceous Hebrew Character (<i>Xestia c-nigrum</i>) in photo 2. <br />
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The curious Latin species name '<i>c-nigrum'</i> makes sense when you know <i>nigrum </i>means 'black in colour', hence literally 'with a black letter ''c''' [on its wings]. (Some of you may remember the 'white letter c' butterfly <i>P. c-album</i> I blogged <a href="http://lifeonanoxfordlawn.blogspot.com/2010/01/comma-butterfly-polygonia-c-album.html">here</a>.)<br />
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I've entirely failed to uncover the meaning of the genus name <i>Xestia</i>. Can anyone comment?<br />
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<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLj23oc0fmRzANl4kZPz12SlDnNH9HLjq0IgZXpKdEW07BPvwphzEojMmHKSkTnD-sSBEnRX5-cMtItDtol57MDTXxkQFnmzi3YGwwIKo1hyphenhyphenl1VvqT99trJyWFRtXgmlfxQzcN4Aw1hk-I/s1600/Setaceous+Hebrew+Character+Xestia+c-nigrum.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="247" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLj23oc0fmRzANl4kZPz12SlDnNH9HLjq0IgZXpKdEW07BPvwphzEojMmHKSkTnD-sSBEnRX5-cMtItDtol57MDTXxkQFnmzi3YGwwIKo1hyphenhyphenl1VvqT99trJyWFRtXgmlfxQzcN4Aw1hk-I/s400/Setaceous+Hebrew+Character+Xestia+c-nigrum.jpg" width="400" /></a></div>Turning to the English common names of moths, I learnt <a href="http://lifeonanoxfordlawn.blogspot.com/2009/04/hebrew-character-orthosia-gothica-and.html">previously</a> that many were invented in the 1730's by the Aurelain society of naturalists. I'd guess (but don't know) those of the moths here were amongst them.<br />
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I needed to look up <i>setaceous.</i> It means whiskery incidentally.<br />
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From the book mentioned above I learn that both my moths are common in the UK. Both overwinter as caterpillars. The caterpillars of the Square Spot Rustic commonly dine on grasses, and those of the Setaceous Hebrew Character on nettles and other herbaceous plants.<br />
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My attempt to learn a little more about my moths led me to some interesting papers by <a href="http://xa.yimg.com/kq/groups/19593555/1659775072/name/Chapman+et+al.+2010+insect+migration+radars.pdf">Chapman et.al</a>. [1] and <a href="http://centaur.reading.ac.uk/1573/1/Wood_etal_2009_BER.pdf">Wood et.al.</a> [2] and The papers describe the authors' efforts to track the migration of insects using ground-based radar. The papers are full of amazing details: I had not hitherto imagined that ground based radar would be so sensitive as to allow tracking of a single grasshopper in flight at a height of 1.5km. Further, as the authors explain, that around the globe millions of tons of insects are aloft at any instant, or that at least 2.3 billion(!) insects were involved in the migrations to/from the UK between 2002 and 2007.<br />
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What it is the insects (many moths, including mine, amongst them) are doing at heights of several hundred metres to a few kilometres is taking advantage of high wind speeds to propel them to places of seasonal migration. The speeds are several times greater than that at which an insect could fly unaided. The authors' studies yielded estimates that by harnessing winds insects may be able to travel as far as ~2000km during only three of four 8-hour flights. Things are not as simple as the insects being mere passive 'leaves in a storm' however. Rather, the authors discovered that they exhibit a clear directional sense, flying at an angle to the main wind direction so as to control where they end up. (I suppose an analogy would be a rowing boat in a strong ocean current. Just because the current may be faster than you could row, by sculling at an angle to the main current it's still possible to steer somewhat). How the insects are able to navigate at altitude and at night the papers don't say. I guess the moon may be involved, but that much about how they do so remains a mystery. <br />
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<span style="font-size: x-small;">References</span><br />
<span style="font-size: x-small;">1. Flight orientation behaviors promote optimal migration trajectories in high flying insects, J.W. Chapman, R.L. Nesbit, L.E. Burgin, D.R. Reynolds, A.D. Smith, D. R. Middleton, J.K. Hill, Science 2010, 327, p.682-685</span><br />
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<span style="font-size: x-small;">2. Flight periodicity and the vertical distribution of high altitude moth migration over southern Britain C.R. Wood, D.R. Reynolds, P.M. Wells, J.F. Barlow, I.P. Woidwod, J.W. Chapman, Bulletin of Entomological Research 99(05), p.525-535, 2009</span>Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com5tag:blogger.com,1999:blog-2834972773043127807.post-74773913120200176212011-10-08T14:46:00.001+01:002011-10-09T13:37:49.515+01:00Cat's Ear Hypochaeris radicata<div class="MsoNormal">I am an amateur naturalist trying to discover everything living in my garden.</div><div class="MsoNormal"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhKIWY00oGbhc-8Q-4olbtfe3rxazEdFH8C4XjWhms6l0FUmm58rwhqHZj93NzYjetQoBVyxTg4LobUDD0pODAz31VQco-E8w1sL7yFMWkwQdp16s9fiahRG7FPTN_UQAneVCbMqmONjPoJ/s1600/Cat%2527s+Ear+Hypochaeris+radicata.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhKIWY00oGbhc-8Q-4olbtfe3rxazEdFH8C4XjWhms6l0FUmm58rwhqHZj93NzYjetQoBVyxTg4LobUDD0pODAz31VQco-E8w1sL7yFMWkwQdp16s9fiahRG7FPTN_UQAneVCbMqmONjPoJ/s400/Cat%2527s+Ear+Hypochaeris+radicata.JPG" width="400" /></a></div><div class="MsoNormal"> The pretty flower in photo 1 is Cat’s Ear - a common weed in my garden. There are a number of superficially similar British yellow-flowered weeds including the Hawkbits, Sow thistles and the Hawksbeards I blogged <a href="http://lifeonanoxfordlawn.blogspot.com/2010/10/smooth-hawks-beard-crepis-capillaris.html">here</a>. From my copy of The Wild Flower Key (Rose) I’m fairly confident my plant is none of these, though I’m less confident it is definitively Cat’s Ear (<i style="mso-bidi-font-style: normal;">Hypochaeris radicata) </i>and not the rather similar Smooth Cat’s Ear (<i style="mso-bidi-font-style: normal;">H. glabra</i>). The book tells me that were my plant to be Smooth Cat’s Ear<i> </i>, then its yellow ‘petals’ would be only twice as long as wide (mine seem longer). Also that the green stems of <i style="mso-bidi-font-style: normal;">H.radicata</i> should broaden as they approach the flower head (more correctly ‘the involucre bract’), which appears to be the case for my plant (see photo 2). On this basis I’m going with the identification <i style="mso-bidi-font-style: normal;">H.radicata</i>.</div><div class="MsoNormal"><br />
</div><div class="MsoNormal"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7Qbuj7QeVsOsW4zHXTgBiHkUAPxju50PafCK5yp2ATl9mEcGgbUvYVbmZh-GFuEOraNfX36cprqzYD1lYmba67tXL62tqkx2fJpMq5x6Bma-C7uu-s8Ihu0hEFhvqgV9M8A8FxiTtXiOg/s1600/Cat%2527s+Ear+Hypochaeris+radicata+bracts.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7Qbuj7QeVsOsW4zHXTgBiHkUAPxju50PafCK5yp2ATl9mEcGgbUvYVbmZh-GFuEOraNfX36cprqzYD1lYmba67tXL62tqkx2fJpMq5x6Bma-C7uu-s8Ihu0hEFhvqgV9M8A8FxiTtXiOg/s200/Cat%2527s+Ear+Hypochaeris+radicata+bracts.JPG" width="200" /></a><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhqklYhD0zCMQb5FUXoLjfeIvA01agIqqFMeHcYoeBy6Syqzvj5kJUeK1a7Hcl1decwxEfRz_nmPc4V_HpCv2PZb_V5XZTyzeEezn_Lp99CG-xY1tmBWZRC4wD_r7s1LJ5u321AtdVHxF95/s1600/Cat%2527s+Ear+Hypochaeris+radicata+leaf.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="100" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhqklYhD0zCMQb5FUXoLjfeIvA01agIqqFMeHcYoeBy6Syqzvj5kJUeK1a7Hcl1decwxEfRz_nmPc4V_HpCv2PZb_V5XZTyzeEezn_Lp99CG-xY1tmBWZRC4wD_r7s1LJ5u321AtdVHxF95/s200/Cat%2527s+Ear+Hypochaeris+radicata+leaf.JPG" width="200" /></a>Readers of my blog will know I try to do a little research to uncover some point of interest for each lifeform I come across. In the case of Cat's Ear my searches led me to <a href="http://www.eco.science.ru.nl/expploec/publ/pdf/HarteminkJongejansDeKroonOikos2004.pdf">an interesting paper [1] by N. Hartemink et.al</a>. The authors asked the question "What does a plant do if you cut the flower buds off?" (these are my words - I'm paraphrasing). A trite answer would be "Grow some more!". Pausing to consider things in more detail however one might begin to imagine more subtle possibilities. Consider a plant growing in a field subject to heavy grazing by animals. If the plant loses a flower one might imagine various responses. For a short lived annual plant, flowering and successfully setting seed in a season is an absolute imperative. One might conjecture that such plants could respond to flower-loss by "stepping up" efforts to produce more and more flowers therefore in the 'hope' that some escape the grazing (of course plants don't 'hope' and this is a poor anthropomorphic description - but, hey, I'm an amateur and it's good enough for me!). By contrast, for long lived perennial plants, flowering does not have the same urgency. If such a plant has its flowers removed, might it simply 'cut its losses' therefore, put 'on hold' attempts to flower and instead put its energies into growing more leaves and roots?</div><div class="MsoNormal"><br />
</div><div class="MsoNormal">To add to these considerations, one should remember also that a plant may not have a simple unfettered 'choice' about whether and how many flowers to grow. Resources (food, water and light etc.) are always finite and may impose further constraints on what types of structure (e.g. flowers vs. leaves) the plant is able to produce. A deeper consideration of this resourcing issue has led the experts to formulate such theories as "meristem allocation". (Meristems are specialised regions of a plant where growth 'happens'. Meristem tissue is found at the tips of roots and shoots for example. It is made up of special meristemic cells that are rapidly growing, dividing and transforming into new bits of root, shoot etc.). I don't understand the 'meristem allocation' theory in detail, but briefly it seems to revolve around the idea that a mersitem at the tip of a plant shoot has a 'choice' to simple carry on creating more and more plant shoot and leaves, or cease making leaves and shoots and instead switch to making a flower. Once the meristem has switched to making a flower however, there is no going back - that meristem is committed and can't later go back to making shoot. In a sense the plant's meristems are like cash in a bank. The plant can keep the 'cash' (mersitems) in the bank growing 'interest' (more shoots and leaves) or 'withdraw' (allocate) some money (meristem) and 'spend it' on a flower. This might all seem rather abstract, but the point is that armed with the idea that meristems are a fundamental unit of 'currency' in the 'economics' of plant survival, botanists can start to construct quantitative and predictive (as opposed to merely descriptive) theories of how plants ought to respond to different environmental pressures (grazing, resource shortages etc.).</div><div class="MsoNormal"><br />
</div><div class="MsoNormal">So, what <i>does </i>a Cat's Ear do when you cut the flowers off?! Well, the authors above took three plant types: Cat's Ear, Devil's Bit Scabious (<i>Succisa pratensis</i>) and Brown Knapweed (<i>Centaurea jacea</i>). They found marked differences in the reponses of these three to removal of flower buds. Both <i>S. pratensis</i> and <i>C. japea</i> responded to flower bud removal by increasing the number of flower buds. Plants of both species would typically make around 7 flower buds per plant if 'left alone', whilst those plants who had their flower buds removed would 'bounce back' and regrow about 12. Interestingly however, <i>S. pratensis</i> also responded by switching some of its energies away from flower bud growth into increasing growth of plant side 'shoots' (strictly side 'rosettes' of new leaves). Appropriately for this blog posting, Cat's Ear's response was the most dramatic all. Plants 'left alone' produced around 60 buds. The 'decapitated' however, bounced back with a dramatic 240. There is much more in the paper that I could talk about, but I've gone on enough here and will simply refer you to the original if you're interested. What I like about the work is it is true science and yet an experiment that any motivated amateur could repeat and extend: find a patch of weeds and a pair of secateurs and you're all set to become a published scientist.</div><div class="MsoNormal"><br />
</div><div class="MsoNormal">Reference:</div><div class="MsoNormal"><span style="font-size: small;">[1] </span><span style="font-family: inherit; font-size: small;">Flexible life history responses to flower and rosette bud removal in three perennial herb, </span>Nienke Hartemink, Eelke Jongejans, Hans De Kroon , Oikos 105: 159-167, 2004.</div><div class="MsoNormal"></div><div class="MsoNormal"></div>Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com2tag:blogger.com,1999:blog-2834972773043127807.post-56686571449050428802011-06-19T13:46:00.001+01:002011-06-20T22:20:14.617+01:00Scenedesmus algaeI am an amateur naturalist trying to discover everything living in my garden.<br />
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<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsiSpPpEzMvyJCN6dwovH0YMFuwBT8WU8SYzSwTk5kJ8AsTVF0lL37LGrLhuwq3Tjel8IQKOtxtFQGSIlGSuYMdHAas6I2uCO9y9cqXD_EpUdnOrlPAKfHNLndzoJIJJlTSpE4RuosAegs/s1600/Scenedesmus+algae.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="298" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsiSpPpEzMvyJCN6dwovH0YMFuwBT8WU8SYzSwTk5kJ8AsTVF0lL37LGrLhuwq3Tjel8IQKOtxtFQGSIlGSuYMdHAas6I2uCO9y9cqXD_EpUdnOrlPAKfHNLndzoJIJJlTSpE4RuosAegs/s400/Scenedesmus+algae.JPG" width="400" /></a></div>Some time ago<a href="http://lifeonanoxfordlawn.blogspot.com/2010/10/rotifer-genus-mniobia.html"> I wrote about</a> a puddle I spotted in my garden. Of course, I bought it into my house in a fishtank (doesn't everyone do this with their garden puddles?!). It was only last week, nine months on, that I finally returned it to the great outdoors. Amazingly it was still brimming with microscopic 'pondlife', although it had become rather choked with the 'sludgy' cyanobacteria I wrote about <a href="http://lifeonanoxfordlawn.blogspot.com/2010/12/two-species-of-cyanobacteria-possibly.html">here</a>.<br />
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Over the months I repeatedly examined my puddle under the microscope. Photo 1 shows one of the lifeforms I found. This one was rather common in the early days, but later seemed to disappear.<br />
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Spot something tiny and green under the microscope and its either algae or cyanobacteria. Cyanobacteria tend to be featureless, lacking detailed internal structure, notably a nucleus. The cells here have nuclei however, helping to identify them as algae. (The nuclei don't show up very clearly in photo 1 but by squinting I think you'll be able to see the spherical features towards the centres of the upper three cells).<br />
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Turning to my (borrowed) copy of the hefty "The Freshwater Algal Flora of the British Isles" (John, Whitton, Brook) - a 700-page light bedtime read! - I was able to identify my algae as a member of the <i>Scenedesmus </i>genus. Characteristic features are the obviously 'pointy' crescent shape. Also, although I occasionally found single, isolated cells, very often I found 4 (as here) or 8 cells together (about which more shortly...).<br />
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<i>Scenedesmus </i>algae are part of the <i>Chlorophyta </i>(= the green algae). They are all freshwater. According to the book above as many as 200 different British species have been reported. However, it's been found that individuals from a species can grow into a variety of different forms as a result of different environmental stresses, so there's suspicion that many of these 200 'species' may not be unique. Furthermore the authors explain that recent scientific studies powered by advances in electron microscopy and modern-day biochemistry are pointing to a need to significantly rethink the traditional classification of many species. (This is happening everywhere in biology these days - see my posting on mushrooms<a href="http://lifeonanoxfordlawn.blogspot.com/2008/05/glistening-inkcap-mushroom-coprinellus.html"> here</a> for example). All this means that although the authors give a key to the 42 British species of <i>Scenedesmus </i>algae they recognise, I've not attempted to pin down the species-identity of mine.<br />
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As I've said many times, I'm rarely disappointed when it comes discovering that there is some fascinating or unusual feature in the lifestyle of any creature I come across. Turning to my copy of R.E.Lee's <i>Phycology </i>(a present Christmas-last) it turns out that the fact I frequently saw 4 or 8 algal cells together was no accident. If <i>Scenedesmus </i>is grown in a tank free from predators (such as grazing water fleas) it grows as single isolated 'unicells'. (If you're an algal cell wanting to maximise the amount of sunlight and nutrients reaching you its preferable to keep your distance from neighbours who might otherwise shield or shadow you). However, introduce some predators into the tank and, amazingly, <i>Scenedesmus </i>cells switch to growing in small groups as an anti-grazing defence! In the jargon, a group is known as a <i>coenobium</i>. Some groups also grow long spines, although interestingly the book implies that these are flotation devices to help the colony stay in the light, rather than anti-predator devices per se. The algae are able to detect the presence of predators by detecting chemicals ('infochemicals') in the water that leach from the digestive tract of the predators. Another of nature's tiny miracles!Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com2tag:blogger.com,1999:blog-2834972773043127807.post-21112704976132389932011-06-10T19:03:00.001+01:002011-06-10T22:30:08.365+01:00A Mock Orange Tree - Philadelphus coronariusI am an amateur naturalist trying to learn something about everything living in my garden.<br />
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<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjXxyYilrjoq9ZfPMFryDV-Aj-AnD4_7YugsVM3W-J2IqAcUdGMLhvEQQzl5zhHTp5nQj9mHIzxfZoX329pbjnEamDmJ8e4yfmNI47Pe7DzOPUAUsyR5DvcoqAIVXJvcZ5ulWVyHYbl8b6B/s1600/Mock+Orange+Philadelphus+coronarius.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="266" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjXxyYilrjoq9ZfPMFryDV-Aj-AnD4_7YugsVM3W-J2IqAcUdGMLhvEQQzl5zhHTp5nQj9mHIzxfZoX329pbjnEamDmJ8e4yfmNI47Pe7DzOPUAUsyR5DvcoqAIVXJvcZ5ulWVyHYbl8b6B/s400/Mock+Orange+Philadelphus+coronarius.JPG" width="400" /></a></div>Photos 1 and 2, taken a few days ago, shows the Mock Orange (<i>Philadelphus</i>) bush that grows at the back of my garden. It is a large plant (maybe 4m x 4m) and a fabulous site in early summer.<br />
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And yes, it smells as gorgeous as it looks! A rich honey/jasmine aroma that wafts across my lawn on summer evenings.<br />
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<i>Philadelpus</i> has long been popular with gardeners and plant nurseries stock numerous artificial cultivars. The Mock Orange (genus <i>Philadelphus</i>) and 'true' Orange (genus <i>Citus</i>) are really only distantly related. The genus <i>Philadelphus</i> is part of the large <i>Hydrangeaceae </i>family of plants. I found a species-key <a href="http://www.plantbio.uga.edu/herbarium/seshrubs/Keys/Philadelphuskey.htm">here</a>, and my plant keys out as <i>Philadelphus coronarius</i>.<br />
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<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgTwMuo07Pueh_KOXFfXUnGBO5AQ0CIDpSn9wRyi2Sm-UGPQ3hOcJfbaSnb472zJ4-71i37z5g0aAi4PPsYqa13kh-ZFhVTRQJVjsqY17AIgdjT7SeisnDu5UxWmTn623XAkeJafnubDKyO/s1600/Mock+Orange+Philadelphus+coronarius+%25282%2529.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="212" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgTwMuo07Pueh_KOXFfXUnGBO5AQ0CIDpSn9wRyi2Sm-UGPQ3hOcJfbaSnb472zJ4-71i37z5g0aAi4PPsYqa13kh-ZFhVTRQJVjsqY17AIgdjT7SeisnDu5UxWmTn623XAkeJafnubDKyO/s320/Mock+Orange+Philadelphus+coronarius+%25282%2529.JPG" width="320" /></a></div>Seeing a thin dusting of yellow pollen on many of the leaves I was inspired to get out my trusty student microscope. I enjoy fiddling around with microscopes and I'm a little surprised that in many years of doing so I've never before looked at pollen. For any beginnner like me who wants to have a go, there are a few tips it may help to know:<br />
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Firstly, something I hadn't previously realised is that plants release their pollen in a dehydrated state (15-35% water content is typical [ref.1]). I guess (but don't know) they do this to keep their weight low and so assist their transportation by wind or insects. Also, desiccation may help prolong the active lifespan of the grain. Dehydrated and hydrated grains can look significantly different (see photo 3).<br />
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A second thing it helps to know is that pollen grains often have a waxy surface coating. This can be a nuisance for microscopy as it may cause grains to stick together. It also obscures fine surface features of the grains.<br />
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Fortunately, both rehydration of pollen grains and removal of their waxy layer is easily achieved by simply wetting them with a few drops of alcohol.<br />
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<div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhjA0YZwf9DLI7A4icpllx0Tl6Ija7JGN1EBk7x8Gw-4rtR0lsxYJVT__eB7ykHf8sPkosdh6OvDPVwLsogXlSqLaeqWcTFY5Pfi2uLcYNtN6-2mCY0TAJSXNxVEZsvoIGvKVHPWqN8m4fO/s1600/Mock+orange+Philadelphus+coronarius+pollen.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="266" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhjA0YZwf9DLI7A4icpllx0Tl6Ija7JGN1EBk7x8Gw-4rtR0lsxYJVT__eB7ykHf8sPkosdh6OvDPVwLsogXlSqLaeqWcTFY5Pfi2uLcYNtN6-2mCY0TAJSXNxVEZsvoIGvKVHPWqN8m4fO/s400/Mock+orange+Philadelphus+coronarius+pollen.jpg" width="400" /></a></div>Once you've looked at your pollen slide you can of course simply throw it away. Microscope users will know however, it is possible to make a collection of semi-permanent slides by encapsulating specimens in glycerine jelly. You can buy glycerine jelly especially designed for pollen. The jelly contains red dye that stains the grains and makes it easier to see fine details on their surfaces.<br />
<br />
Anyway, photo 3 shows the results of the above: circular/triangular pollen grains about 12microns across.<br />
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Seeking to learn some more about pollen, I came across a nice review paper by Edlund et.al. <a href="http://www.plantcell.org/content/16/suppl_1/S84.full">here</a> [ref.1]. The paper highlights various areas where the science behind pollen is unexplored or only partly understood. Take for example the functioning of the outer coating of pollen grains (the <i>exine</i>). This layer can be extremely ornate. Often it is riddled with cavities containing exotic plant proteins. When a dehydrated pollen grain lands on the 'female' stimga in the centre of a flower of the same species, something about the surface of the grain causes it stick fast, when pollen from a different species doesn't. The science behind this 'selective adhesion' is only partly understood.<br />
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Once a grain has stuck, chemicals are exuded by the stimga that rehydrate the pollen in a matter of minutes. Once again, this can be exquisitely selective. Two species of pollen grain can be put, side-by-side, onto a single stigma, and only the pollen grain from the correct species will be rehydrated. How nature manages to pull off this clever stunt is again something of a mystery.<br />
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With the grain re-hydrated, it germinates and sprouts a single tube that grows its way down the stimga. (There's a fun article by <a href="http://www.microscopy-uk.org.uk/mag//artdec99/jgpollen.html">Chris Thomas here</a> that describes how to observe pollen tubes by sprouting grains on a piece of onion skin). Eventually the pollen tube contacts with a female egg at the base of the stigma and the pollen grain sends its DNA down the tube to fertilise the egg. (Pollen grains are a mechanism by which DNA is carried between plants. Its wrong to think of them as 'male sperm' however since a pollen grain is mostly comprised of bundles of 'normal' vegetative plant cells.)<br />
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Some plants rely on wind to spread their pollen. Others, animals and insects. Something new I learnt was that one plant- <i>Lagerstroemia </i>- is so keen to attract the latter it produces two types of pollen: a sterile, yellow, feeding pollen and a fertile, blue one.<br />
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My first microscope observations of pollen were great fun and I learned a lot. It turned out my Mock Orange had an another interesting microscopic feature for me. What it was however, will need to wait for another posting.<br />
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<br />
Reference<br />
[1] Pollen and Stimga Structure and Function, A.F. Edlund, R. D. Swanson, Preuss, The Plant Cell 16:S84-S97 (2004)Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com1tag:blogger.com,1999:blog-2834972773043127807.post-64749154042642839422011-06-04T17:50:00.001+01:002011-06-07T22:17:08.826+01:00Hedge Bindweed Calystegia sepiumI am an amateur naturalist trying to discover everything living in my garden.<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh86yHabm5UpBwD87Bvv7RSitACHDAbgG7WokFR9Ypply5Q6umLOsbeQWhvboWn-vi5MqhIKp7sjAAWpo1x4x4eqNTy7mH0kcBVbtSNrkhCR6L89eSJELK2wwdn5uNEDL36-ohL_xX1SMq5/s1600/Hedge+bindweed+Calystegia+sepium.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh86yHabm5UpBwD87Bvv7RSitACHDAbgG7WokFR9Ypply5Q6umLOsbeQWhvboWn-vi5MqhIKp7sjAAWpo1x4x4eqNTy7mH0kcBVbtSNrkhCR6L89eSJELK2wwdn5uNEDL36-ohL_xX1SMq5/s320/Hedge+bindweed+Calystegia+sepium.jpg" t8="true" width="213" /></a></div>Photos 1 and 2 show some Hedge Bindweed (Calystegia sepium) - a weed that pops up frequently in my garden.<br />
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My copy of The Englishman's Flora (Geoffrey Grigson) lists dozens of alternative names for this common plant, from the pretty <i>Rutland Beauty</i>, <i>Shimmy-and-Buttons</i> and <i>Robin-run-the-Hedge</i>,to the sinister <i>Devils Garter</i>, <i>Strangleweed</i> and <i>Devil's Guts</i>.<br />
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A name not in the book is the one my mother taught - <i>Granny Pop the Bed</i> - so called because if you squeeze the green base of the trumpet shaped head (see photo 2) the white flower pops out. It's not a very convincing pop it has to be said, but hey, when you're six its great!<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjH4zCrncs6E7Oq8vtL5iTqsCebzf9MDFtYL7EK-ggSOYBh9Zje10IJYoJTAZlBtLZ8oLwHuwaRsfIzFtfypa_MMd_EjfOuP1p0-OCK0V_Z2y4RmH0s9x_Ud807L_EgjH5NYizFQwFEyP0u/s1600/Hedge+bindweed+Calystegia+sepium+2.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjH4zCrncs6E7Oq8vtL5iTqsCebzf9MDFtYL7EK-ggSOYBh9Zje10IJYoJTAZlBtLZ8oLwHuwaRsfIzFtfypa_MMd_EjfOuP1p0-OCK0V_Z2y4RmH0s9x_Ud807L_EgjH5NYizFQwFEyP0u/s320/Hedge+bindweed+Calystegia+sepium+2.jpg" width="213" /></a><br />
In the jargon, the green flower base is called the <i>calyx </i>(I've labelled this in photo 2). The 'leaves' that make it up are called <i>sepals</i>. C.sepium also has an outer <i>epicalyx</i>.<br />
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When I first started this posting I took it for granted that a web search would turn up scores of scientific papers on my common weed. As it turned out I struggled to find any! I did come across a research paper [<a href="http://users.sdsc.edu/%7Eyoukha/duplication/_B_BARRELS/b78_b77_Beta-Prism/Structure_Agglutinin_lectin_beta-prism_dimer_trimer_ring_carbohydrate_binding.pdf">1</a>] on the apparently unusual lectin (a protein) biochemistry chemistry of my weed, but the subject matter was rather technical and I'm not expert enough to do it justice here. This aside most of the material I did manage to find concerned the related Field Bindweed (C<i>onvolvulus arvensis</i>), a target for frequent study because it is a major weed of arable crops. (Field- and Hedge Bindweed can be readily distinguished by knowing that Field Bindweed doesn't have an <i>epicalyx</i>).<br />
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This lack of literature meant that for a time I was left wondering what to say in this post, but then I recalled an unusual fact concerning Bindweed's spiral growth which I'd read about some time ago (I don't remember where). Photo 1 shows a plant climbing a garden cane. As it climbs the stalk is seen to spiral in an anticlockwise direction (as viewed from above). What's interesting is that C.sepium <i>always </i>spirals anticlockwise. (I've even been around my garden checked! Indeed once you know this fact, its hard resist the temptation to check the spiral of every Hedge Bindweed you see anywhere!).<br />
<br />
This feature of always twisting one way turned out to be rather a rich topic for exploration. Amongst others I was led to a paper by Thitamdee et.al. [2] on the origins of spiral forms in plants:<br />
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The authors' studies focused on plant <i>microtubules</i>. These are molecular sized rods found in both plant and animal cells (they've received mention on my blog before, <a href="http://lifeonanoxfordlawn.blogspot.com/2010/10/smooth-hawks-beard-crepis-capillaris.html">here</a>). Its been discovered that large numbers of these rods decorate the surface of plant cells (like matchsticks stuck on a balloon). The rods do not lie randomly on the surface of the cells however, rather they order themselves so as to line up along a common direction. There's some amazing video of real microtubules jostling about on cell surfaces on the webpage of Indiana University's Shaw Lab. <a href="http://sites.bio.indiana.edu/%7Eshawlab/">here</a>. Now, to continue the balloon analogy, imagine having a lot of matchsticks densely glued to the surface of one of those sausage shaped party balloons. Imagine the matches are all lined up so as point around the short, circular axis of the balloon (like hoops around a barrel). Next, imagine blowing more air into the balloon. Though I haven't actually done the experiment, I hope its reasonable to suggest that the rigid matches would make it more difficult for the balloon to swell in circular cross-section (get 'fatter'), and instead the balloon would grow more freely lengthwise (get longer). This is exactly what aligned microtubules are believed to do for plant cells i.e. cells that would otherwise grow and expand as simple spheres are instead constrained to grow and expand along a preferred direction. This is useful because it allows the plant to create e.g. long, thin cells suitable the plant stalk. (Actually, strictly its not microtubles themselves that constrain the growth of the cell walls, rather the microtubles appear to act as markers for the laying down of a secondary stiffening material - cellulose - but the principle's the same)<br />
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Now, Thitamdee et.al. were studying a cress plant called <i>Arabidopsiss. </i>This is famous amongst botanists as <i>the </i>plant for genetic studies worldwide. Normal <i>Arabidposis</i> plants don't spiral, they grow straight. Furthermore, when scientists looked at the microtubules on cells in the stalk they found them to be arranged exactly as in the description above (i.e. 'hoops around a barrel')<br />
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What Thitamdee <i>et.al.</i> discovered however, was that a mutation in a single gene can cause a change in the way microtubles on cells in the stalk of an <i>Arabidopsis </i>plant arrange themselves. Specifically, they observed mutations that caused the microtubules to shift from being aligned all-parallel to the cell circumference ('hoops around a barrel') to instead all lying on the cell surface at an angle to the long axis of the cell.<br />
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And what did these mutant plants, with their slanted microtubles, do? Yep, grow in a spiral!<br />
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The importance of this work is that it implies an explanation for why some plants spiral and some don't, and furthermore why, for many species, every individual must spiral in the same direction: Things are dictated by the angle at which microtubles are aligned on the cells. This in turn is hardwired by the plant's DNA. Perhaps an ancient ancestor of Hedge Bindweed grew straight. At some point however a gene mutation arose that caused the microtubles to align at some new angle. With this angle fixed by the DNA, the Bindweed's fate was fixed; Subservient to the constraining forces acting on its cell walls, it was doomed to spiral, and always in the same direction, this being dictated by the angle of microtubule alignment (though what this is specifically I don't know - I haven't found any reference to suggest the microtuble alignment of <i>C. sepium</i> specifically has been studied). <br />
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To end, a bit of humble pie. When I first recognised the anticlockwise spiralling of Bindweed, I admit I thought I was rather clever in having uncovered some little known fact... until, that was, I discovered that my supposed 'little known fact' even had its own popular 1950's song!<br />
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<span class="Apple-style-span" style="font-size: 16px;"><i><span class="Apple-style-span" style="font-family: inherit;">The fragrant honeysuckle spirals clockwise to the sun, </span></i></span><br />
<span lang="EN" style="font-size: 12pt;"><i><span class="Apple-style-span" style="font-family: inherit;"> And many other creepers do the same. <br />
But some climb anti-clockwise, the bindweed does, for one, <br />
Or Convolvulus, to give her proper name... </span></i></span><br />
<div><span lang="EN" style="font-size: 12pt;"><i><span class="Apple-style-span" style="font-family: inherit;">( from </span></i></span><span class="Apple-style-span" style="font-size: 16px;"><i><span class="Apple-style-span" style="font-family: inherit;">Misalliance</span></i></span><span class="Apple-style-span" style="font-size: 16px;"><i><span class="Apple-style-span" style="font-family: inherit;"> by Flanders and Swann, ).</span></i></span></div><div><span lang="EN" style="font-size: 12pt;"><i><br />
</i></span></div><div><span lang="EN" style="font-size: 12pt;"><span class="Apple-style-span" style="font-family: inherit;"></span>References</span></div><div style="font-family: Arial,Helvetica,sans-serif;"><span lang="EN" style="font-size: x-small;"><div><i>[1] </i><i><div style="display: inline ! important;">The Crystal Structure of the Calystegia sepium Agglutinin Reveals a </div></i><span class="Apple-style-span" style="font-style: italic;">Novel Quaternary Arrangement of Lectin Subunits with a </span><i>Prism Fold, </i>Y Bourne et.al., <span class="Apple-style-span">The Journal Of Biological Chemistry, 279(1),pp. 527–533, 2004</span></div><div><i>[2] Microtubule basis for left-handed helical growth in Arabidopsis</i><span class="Apple-style-span">, S. Thitamadee, K. Tuchihara & T. Hashimoto, Nature, 417, p.193, 2002.</span></div></span></div><div><span lang="EN" style="font-size: 12pt;"><i><br />
</i> <br />
</span></div>Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com5tag:blogger.com,1999:blog-2834972773043127807.post-87545990903819154412011-06-02T22:33:00.002+01:002011-06-02T22:36:13.550+01:00A Grey Squirrel Sciurus carolinensisI am an amateur naturalist trying to learn something about everything living in my garden.<br />
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<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJmXJ3z-YKqIjpyyngzdOF09ZSzz8gZ709IT8PT3aqPpjEaWhD2a0VgVJAlZWP80pQW_bdE569v7DlEWRL3_XpiHJmM4dVK9MEGymuszGaBM2k1iTwnhBCOXrFNXmfTR94vkYduaeHyRLx/s1600/grey+squirrel+Sciurus+carolinensis.jpg" imageanchor="1" style="clear: left; cssfloat: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJmXJ3z-YKqIjpyyngzdOF09ZSzz8gZ709IT8PT3aqPpjEaWhD2a0VgVJAlZWP80pQW_bdE569v7DlEWRL3_XpiHJmM4dVK9MEGymuszGaBM2k1iTwnhBCOXrFNXmfTR94vkYduaeHyRLx/s400/grey+squirrel+Sciurus+carolinensis.jpg" t8="true" width="266" /></a></div>Photo 1 (strictly I took this particular photo in a local park) shows a sporadic visitor to my garden, and my third mammal, the Grey Squirrel (<em>Sciurus carolinensis</em>). <br />
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To learn something about them I have been reading <em>Squirrels</em> by Jessica Holm (Whittet Books).<br />
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Together with the Red (<em>Sciurus vulgaris</em>) the Grey is one of two species of squirrel found in Britain. It is a North American import. The first pair was released by a Mr Broklehurst in the county of Cheshire in 1876. Famously, the Grey has thrived (indeed, they are legally classified as vermin), whilst the once common Red is today a protected species clinging on in a handful of isolated locations (I have only ever seen one myself- in Cumbria). <br />
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Why the populations have changed in this way is not entirely understood. It is often said (indeed, before reading Dr. Holt's book I too had lazily assumed) that the Greys have 'driven' the Reds from their 'territories'. This is false on two counts however: Firstly, in woodlands where both have been studied together its found that Reds and Greys do not show any undue aggression towards one another. Secondly (and a surprise to me) squirrels aren't territorial animals. The life of a squirrel is a 'roaming' one (though generally confined to some home range of a kilometer or so). Rather than all-out interspecies hostility, it seems that the Red population may have declined as a combination of diseases passed on by the invaders and because the smaller size of the Reds means they are less able to gather food in areas where the more avaricious Greys are eating much of it up. Totally, more study is necessary however.<br />
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A few additional things of interest I picked up from my reading are firstly that Reds and Greys normally carry distinct species of flea (<em>Monopsyllus sciuronum</em> for the Reds, <em>Orchopeas howardii</em> for the Grey). Mother Nature is nothing if not an expert in specialisation! Secondly, watching a squirrel work through a pile of nuts, it will sometimes be observed to discard one without opening it. These turn out to be bad nuts with withered kernels. How the squirrel determines this with the nut still in its shell is rather impressive. It weighs them in its paws. A neat party trick!<br />
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To end, the literature abounds with Squirrel poems and Beatrix Potter quotes, but for me there is only one winner of the prize for top squirrel literary moment:<br />
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<em>The squirrels pulled Veruca to the ground and started carrying her across the floor. </em><br />
<em>"My goodness she is a bad nut after all" said Mr Wonka, "Her head must have sounded quite hollow" [...] </em><br />
<em>"Where are they taking her?" shrieked Mrs Salt.</em><br />
<em>"She's going where all the other bad nuts go" said Mr Willy Wonka. "Down the rubbish chute."</em><br />
<em>[Roald Dahl, Charlie and the Chocolate Factory]</em>Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com1tag:blogger.com,1999:blog-2834972773043127807.post-59681653286382561802011-05-31T21:50:00.006+01:002011-05-31T21:58:05.355+01:00A long legged Dolichopus flyI am an amateur naturalist trying to discover everything living in my garden. <br />
<div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br />
</div><div><div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiP7Vc1bacRyekKkCU4LhQhR05BIZEce-j9F9bcAEFgOjGGAt7Ta9_4BcfCJzrpLqnIs15W3APXvFkJ0yeGUY3amputoCO-hmrQsro8Sop1TQKrIc3IXHai7FW3Ex8MuYPssYyUkPoOXEX9/s1600/Long+legged+Dolichopus+fly.jpg" imageanchor="1" style="clear: left; cssfloat: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="266" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiP7Vc1bacRyekKkCU4LhQhR05BIZEce-j9F9bcAEFgOjGGAt7Ta9_4BcfCJzrpLqnIs15W3APXvFkJ0yeGUY3amputoCO-hmrQsro8Sop1TQKrIc3IXHai7FW3Ex8MuYPssYyUkPoOXEX9/s400/Long+legged+Dolichopus+fly.jpg" t8="true" width="400" /></a></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">For some time I have hankered after a garden pond (there are few things better for encouraging wildlife into one's garden). On a whim, I recently took the plunge (sorry, terrible pun!) and dug one. Though only a few weeks old, already I'm seeing enough life to keep me busy blogging long into the future.</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br />
</div></div></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">Photo 1 shows two flies sunning themselves at the water's edge. There were several dozen around the pond. </div></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">The 'colony' was a constant flicker of activity and it was this that first caught my attention. Individual flies seemed to be attracted to movement and if another landed closeby they would quickly go 'into action', advancing rapidly towards the new comer. In a few cases one would even jump on top of another and the two launch into flight (at which point it was impossible to follow them by eye). </div></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br />
</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjTa6-PFvmw5H5UxURbrPnrbTXWA72DSIjT3iKIf8xpTu4Ss42rFtwtSeU_UT1reTRa4b1nLVNbw-HvEvtgSvu6fZjQIhqBJAuaEoUMr53d5ssgX0OVHxVNydNDLHzCMZkB4Vwli9SLsVCO/s1600/Dolichopus+fly+rubbing+legs+2.jpg" imageanchor="1" style="clear: left; cssfloat: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="213" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjTa6-PFvmw5H5UxURbrPnrbTXWA72DSIjT3iKIf8xpTu4Ss42rFtwtSeU_UT1reTRa4b1nLVNbw-HvEvtgSvu6fZjQIhqBJAuaEoUMr53d5ssgX0OVHxVNydNDLHzCMZkB4Vwli9SLsVCO/s320/Dolichopus+fly+rubbing+legs+2.jpg" t8="true" width="320" /></a>I observed a number of instances of one fly standing close by another and methodically rubbing its back legs together. I've highlighted this with an arrow in photo 2. I recently wrote at length about the courtship signalling behaviour of a related fly (<a href="http://lifeonanoxfordlawn.blogspot.com/2010/04/signalling-fly-poecilobothrus.html">Poecilobotus nobilatus</a>) I found in my garden. I would like to think I was observing something similar here. Whether I was however, or whether it was just some coincidental preening I can't be sure (can anyone comment?).<br />
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</div></div></div></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">So, how about the identity of my fly? Unfortunately, for the non-expert (=me!), identifying a fly is a decidedly non-trivial business. Firstly, a low power microscope is pretty much essential. Next, you need to be fortunate in finding an identification key. After that you need to be prepared to work through the copious technical jargon that the specialist keys will hurl at you. Finally you need the magic ingredient: experience!</div></div></div></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br />
</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjAf_01Vy__n26_YgAo6j7qBIFUU0sMMm77_ziFyCkmyz1Me1M54CuNN2eFSGD07PMs_XSqMYhdiRegPNZNl6bCWrEyUXu760BdLDggZaUIplzOptrDksHh-i5pSn05Ng87j5Q5oZ5jefC2/s1600/Detail+of+a+Dolichopus+fly+2.JPG" imageanchor="1" style="clear: left; cssfloat: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjAf_01Vy__n26_YgAo6j7qBIFUU0sMMm77_ziFyCkmyz1Me1M54CuNN2eFSGD07PMs_XSqMYhdiRegPNZNl6bCWrEyUXu760BdLDggZaUIplzOptrDksHh-i5pSn05Ng87j5Q5oZ5jefC2/s320/Detail+of+a+Dolichopus+fly+2.JPG" t8="true" width="240" /></a>How did I fair against this list? Well, I have a microscope; I was also fortunate to find the free online <a href="http://www.field-studies-council.org/fieldstudies/category/terrestrial.htm">key by Dennis Unwin</a> to the families of British Diptera, and <a href="http://grichanov.fortunecity.com/SwedenGenera.htm">"A Key To Swedish Dolichopodidae" by Igor Grichanov</a>; For several hours I diligently applied myself to translating the jargon in the keys and scrutinising my fly's features. I was able to determine that my fly's "post ocular setae" (=bristles behind the eyes) are long and all of them black (see '1' in photo 3). Also, that the base of my fly's antennae sprout tiny hairs (see '2' in photo 4); that the shape of it's "occiput" (= the back of the head) is convex (see '3') and that it sprouts two rows of "acrostichal setae" (=hairs down the centre of its back - see '4'). I worked through a dozen other similar features. </div></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br />
</div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">And the result of all my efforts? Well, further aided by a study of my fly's wings (see my discussion of insect wings <a href="http://lifeonanoxfordlawn.blogspot.com/2010/12/crane-fly-in-family-limonia-nebeculosa.html">here</a>) I'm <em>confident</em> that amongst the 80-odd families of British fly, mine is a member of the family <em>Dolicopodidae</em>. Next, I'm <em>fairly confident</em> that of the 30-odd genera within this family, mine is a member of the <em>Dolichopus</em> genus. And finally, of the 51 British species within this genus (I got this number from the Dipterists Forum website)... well, I am <em>not at all confident</em> (!) mine is a <em>Dolichopus ungulatus.</em></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><br />
</div></div><div style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">The one thing you can't look up is experience.</div></div></div>Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com3tag:blogger.com,1999:blog-2834972773043127807.post-31532463818532148542011-04-29T17:10:00.022+01:002011-04-30T14:59:36.650+01:00A spider Meta segmentataI am an amateur naturalist trying to learn something about everything living in my garden.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLU7VTgUjIhPT090imM2nfad-L7LMWwJcewiu4HGn_5GDC9Quv-xpfCGYzeMe4CnyBl6v8D44zLMRFQiMuf-ke9Y8toROFOGDW5p8SDk90akc0ve-5lxFkybQiyAT-1D8prLycPG_mDgaY/s1600/Meta+segmentata+spider+male+4.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 400px; height: 288px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLU7VTgUjIhPT090imM2nfad-L7LMWwJcewiu4HGn_5GDC9Quv-xpfCGYzeMe4CnyBl6v8D44zLMRFQiMuf-ke9Y8toROFOGDW5p8SDk90akc0ve-5lxFkybQiyAT-1D8prLycPG_mDgaY/s400/Meta+segmentata+spider+male+4.jpg" alt="" id="BLOGGER_PHOTO_ID_5601295155724524066" border="0" /></a>Photo 1, taken late last summer, shows a spider about half-a-centimetre long. Spiders are surprisingly tricky to identify. You might think their often striking colour patterns would make things easy. Unfortunately for many species this is rather variable and the only really accurate approach to identification is to examine your arachnid's reproductive parts under a hand lens. I didn't subject my spider to the indignity of this. From the illustrations in my copy of <span style="font-style: italic;">Spiders</span> (M.Roberts, publ. Collins) however I'm tolerably confident the species here is either <span style="font-style: italic;">Meta segmentata</span> or <span style="font-style: italic;">Meta mengei</span>. Both are common in Britain and look very similar. From the season (<span style="font-style: italic;">M. segmentata</span> is more common later in the year and <span style="font-style: italic;">M. mengei</span> earlier) and from the book illustrations which show <span style="font-style: italic;">M. mengei </span>with a more distinctly hairy lower-leg ('metatarsus I and II' - I've marked these with the white line in photo 1) than my spider appears to possess, I'm going with the identification<span style="font-style: italic;"> M. segmentata</span>.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvdx61FfBZ3k_8dFTUkKtHm46WKCk3CQXM1AmJEq_vV45WClCgwZIf7jIkTQhyphenhyphenV27rOXqXwb3UZFRnSYlHwhva4bMYLtHmuAjo-Cl-QlK2Tr_TDqqinwFHZxChwHsUifZYLeHeuIRqT9Jo/s1600/Meta+segmentata+male+spider+2.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 320px; height: 214px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvdx61FfBZ3k_8dFTUkKtHm46WKCk3CQXM1AmJEq_vV45WClCgwZIf7jIkTQhyphenhyphenV27rOXqXwb3UZFRnSYlHwhva4bMYLtHmuAjo-Cl-QlK2Tr_TDqqinwFHZxChwHsUifZYLeHeuIRqT9Jo/s320/Meta+segmentata+male+spider+2.jpg" alt="" id="BLOGGER_PHOTO_ID_5601296542332774994" border="0" /></a>The spider here is a male as revealed by the presence of the two little 'boxing gloves' (the 'palps') emerging just in front of the head. You can see these most clearly in photo 2.<br /><br />In the course of writing this blog I have learnt to expect that any creature I come across will have some complex and fascinating aspect to its lifestyle. As I discovered from browsing various online papers (<a href="http://www.princeton.edu/%7Edir/pdf_dir/1987_Rubenstein_BehEcolSoc.pdf">1</a>,<a href="http://sites.google.com/site/johnprenter/Prenteretal2003AnimBehav-12.pdf"> </a><a href="http://sites.google.com/site/johnprenter/Prenteretal2003AnimBehav-12.pdf">2</a>, <a href="http://www.minds.nuim.ie/%7Edavy/Davy/Davy/Dissertation/papers/Read/sdarticle.pdf">3</a> - references below) <span style="font-style: italic;">M. segmentata</span> is no exception. The mating strategy of male <span style="font-style: italic;">segmenta's</span> is one example of the rich topics for exploration:<br /><br />If you're a male <span style="font-style: italic;">M.segmentata</span> wanting to mate with a female it does not pay to approach her directly. Do this and its likely she'll eat you! Why it benefits some lifeforms to routinely indulge in cannibalism and others (we human males might say, thankfully) not is a puzzle in itself. Anyway, regardless of the reason, the best chance a male <span style="font-style: italic;">M.segmentata</span> has of mating with a female is to approach her at just the moment she has caught a nice juicy fly and is sufficiently pre-occupied not to eat her suitor. In detail, what males actually do is to approach the female on her web, drive her off her catch and cut the threads supporting the dead fly so that it dangles from a single 'nuptial' thread. The male then mates with the female whilst she attempts to recover the catch.<br /><br />For the male to be present at just the moment a female catches a fly requires that he sits, sometimes for weeks, watching her web. This is known as 'mate guarding' (in my <a href="http://lifeonanoxfordlawn.blogspot.com/2011/04/common-darter-dragonfly-sympetrum.html">previous posting</a> I discussed mate guarding amongst dragonflies). Mate guarding for male <span style="font-style: italic;">M.segmentata's</span> is a high energy-expenditure task<span style="font-style: italic;"></span>. Not only may his own food supply suffer, but he is also exposed to challenges from other males who want to usurp his position of guarding a receptive female. (It seems that males know receptive females by the presence of pheromones on her web). The whole question of why it pays males in nature to expend considerable energy to mate is a very deep and rich one in biology (I said something about it in my posting <a href="http://lifeonanoxfordlawn.blogspot.com/2010/04/signalling-fly-poecilobothrus.html">here</a>). An illustration of how subtle things can become is afforded by the studies of Rubenstein and others above (ref.1) on <span style="font-style: italic;">M. segmentata</span>:<br /><br />Careful studies of colonies of <span style="font-style: italic;">M. segmenta</span> (e.g. on an isolated bushes) show that over a season, a 'size hierarchy' develops with the biggest healthiest males taking over guarding the biggest healthiest females. Once a big male has succeeded in mating with a female, he will move on and find another big female to start guarding. He may need to battle with an already on-guard male to win the right to guard this new female, but being large he stands a decent chance of winning any such battles. In this way big males get to mate with lots of big females and enjoy high reproductive success.<br /><br />Little males have no hope of winning at this 'roaming' lifestyle however. They would constantly lose the battle to guard large females to larger males. So instead, small males adopt an alternative strategy and choose monogamy, 'settling down' with a single small female. Being small, she herself will normally have been pushed out to an 'undesirable' part of the colony (low down on the bush, say) where prey is scarce. Her small size and poor diet will mean she is not likely to be very fertile (she will not produce a lot of eggs). However, in settling down with her the little male avoids the alternative of a series of fruitless battles over larger females.<br /><br />So far so good, but now, the question arises: What of mid-sized males? Should they roam, continually seeking large, fertile females to guard but mostly losing them in battles with large males? Or do as small males do and 'settle down' with a single female, but at the cost their mate may have low fertility. In the studies of Rubenstein, 86% of medium males opted to roam. Precisely why the odds stack in this direction doesn't seem to be understood; a nice example of how subtle behaviours can be in the natural kingdom and how there are plenty of topics awaiting further study.<br /><br /><span style="font-weight: bold;">References</span><br />1. Alternative reproductive tactics in the spider Meta segmentata, D.I.Rubenstein, Behav. Ecol. Sociobiol. (1987) 20:229-237<br />2. Mate guarding, competition and variation in size in male orb-web spiders, Metellina segmentata: a field experiment. J. Prenter, R. W. Elwood, W.I. Montgomery, Animal Behaviour, 2003, 66, 1053–1058<br />3. The influence of prey size and female reproductive state on the courtship of the autumn spider, Metallina segmentata: a field experiment, J. Prenter, R. Elwood, S. Colgan, Anim. Behav. 1994, 47, 449-456.Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com2tag:blogger.com,1999:blog-2834972773043127807.post-62733893887751324632011-04-23T14:52:00.017+01:002011-04-25T09:47:40.884+01:00Common Darter dragonfly Sympetrum striolatumI am an amateur naturalist trying to learn something about everything that lives in my garden.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjthkhuriuQsTMPhJFv7YC8i64xU1_jl4hLtmdyg1Slx__6MI5WUbtkjFox81liY4N8iriGValxdwR2E4ryKFKEEtEiY4QFgXVSw-fbvCc_yexHmKi5kG2bGelUU4X5sftqiQ9tGt1KiTjl/s1600/common+darter+dragonfly+Sympetrum+striolatum+2.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 400px; height: 267px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjthkhuriuQsTMPhJFv7YC8i64xU1_jl4hLtmdyg1Slx__6MI5WUbtkjFox81liY4N8iriGValxdwR2E4ryKFKEEtEiY4QFgXVSw-fbvCc_yexHmKi5kG2bGelUU4X5sftqiQ9tGt1KiTjl/s400/common+darter+dragonfly+Sympetrum+striolatum+2.jpg" alt="" id="BLOGGER_PHOTO_ID_5598779466316173378" border="0" /></a>Photo 1, taken back in Autumn shows one of Britain's forty-or-so dragonfly species. Referring to the magnificant colour photos in my copy of <span style="font-style: italic;">Britain's Dragonflies</span> (Smallshire and Swash) I'm confident this is one of the commoner species, The Common Darter (<span style="font-style: italic;">Sympetrum striolatum</span>). The yellow stripes down the legs indicate this one is a male. Adult Common Darters can be found on the wing from March through to earlier December if the weather is mild.<br /><br />Two dragonflies were present the day I took photo 1. This is the first time I have seen them in my garden. About a kilometre from my house there is a large expanse of wetland however and there, at times, I have seen swarms of several hundreds.<br /><br />To learn something about dragonflies I have been reading the book of the same name by Corbet and Brooks (New Naturalist Series). I particularly enjoy natural history writing that educates you about not only what is known, but also what isn't. The book is fully satisfying in this respect, concluding each chapter with a section 'Opportunities for Investigation', listing projects of genuine scientific value that any sufficiently motivated amateur might tackle.<br /><br />The book opens with a discussion of habitat selection: Many dragonfly species are selective over the habitats they will adopt as breeding sites. Some demand flowing water, others still. Some require the presence of certain types of aquatic vegetation. Some will select a pond only if the trees on the bank are below a certain height. Etc. It's hypothesised that an adult arriving at a new location runs through a checklist of 'proximal cues': 'Is it water?' -> 'No', then fly on / 'Yes' then 'Is the water flowing?' -> 'No', fly on / 'Yes', then are there trees on the bank... What the cues are for many species isn't understood however. The fact that adults have been observed being fooled into, for example, trying to lay eggs into a wellington boot (!) suggests one line of enquiry might be careful experimental manipulation of environmental cues to try to work out those that appeal to different dragonfly species.<br /><br />The topic of reproductive behaviour is a very rich one for study. The authors break things down into the four stages of Recogition (of a prospective mate); Sperm transfer; Guarding Behaviour; and Oviposition. Guarding behaviour is the habit amongts the males of many species (including my <span style="font-style: italic;">S. striolatum</span>) of staying with a female even after she has been fertilised. The males of some species continue to grip the female by the head until she has finished depositing her eggs. Some even 'dunk' the female under water to assist her egg laying into the submerged stems of plants. An advantage of guarding from the male's perspective is that it prevents other males from coming along and displacing his sperm with their own. For the female there are presumed survival advantages: Two sets of eyes are better than one when it comes to spotting predators. Some species even go in for group oviposition, whereby half-a-dozen or more males/female pairs congregate in one spot to lay eggs.<br /><br />There are a great many opportunities for amateur study concerning the larval stages of dragonflies. Dragonfly larvae go through a number of stages called 'stadia', moulting their exoskelton between each. The stadia for many species however, are simply not known. As the book puts it <span style="font-style: italic;">"there is an urgent need for keys to earlier stadia"</span>.<br /><br />Some species go through all development stages in one year, others 'sit out' the winter in 'diapause', still others have the option to do either. Much remains unexplored concerning the factors that control the development rate of larvae and whether they overwinter or not.<br /><br />Some dragonfly species lay their eggs several metres from the water's edge. How the first larval stadium (a minute limbless 'tadpole') makes its way from the egg-site to the water is again unknown.<br /><br />Finally, there are many opportunities for studying the behaviour of larvae - their strategies for stalking different types of prey for example - that any suitably motivated amateur armed with a fishtank and plenty of patience could attack.<br /><br />There is a great deal more that could be said about the study of dragonflies ('Odontology'). Part of me feels I ought to go on and write more here since I have not seen other dragonfly species in my garden and so may not get a chance to return to them on this blog in the future. On the other hand when I started logging my garden's visitors several years ago I never imagined I would find myself writing about<a href="http://lifeonanoxfordlawn.blogspot.com/2008/09/indian-peacock-and-peahen-pavo.html"> peacocks</a> and<a href="http://lifeonanoxfordlawn.blogspot.com/2007/07/budgie-melopsittacus-undulatus.html"> budgerigars.</a> So perhaps I can afford to take the risk!Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com2tag:blogger.com,1999:blog-2834972773043127807.post-42703061795544518982010-12-30T21:55:00.028+00:002011-06-19T13:58:27.182+01:00Two species of cyanobacteria (possibly Nostoc commune and Anabaena cylindrica)I am an amateur naturalist trying to learn something about everything that lives in my garden.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjObvxaIiI7z74scA_LUm-T68O9YP6KWGyZ-GEGFt-wsLlY9cCM98Az73_3kPbq0dv0HdPrI18AM4o9ed7J6gKm4t3RjXwo2Ykdldndmms7WnlO3YKEyilP-ewtJoyLQGKha-APl1lQLwYC/s1600/cyanobacteria+possible+Anabaena+cylindrica.jpg" onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}"><img alt="" border="0" id="BLOGGER_PHOTO_ID_5556603367743727538" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjObvxaIiI7z74scA_LUm-T68O9YP6KWGyZ-GEGFt-wsLlY9cCM98Az73_3kPbq0dv0HdPrI18AM4o9ed7J6gKm4t3RjXwo2Ykdldndmms7WnlO3YKEyilP-ewtJoyLQGKha-APl1lQLwYC/s320/cyanobacteria+possible+Anabaena+cylindrica.jpg" style="cursor: pointer; float: left; height: 214px; margin: 0pt 10px 10px 0pt; width: 320px;" /></a>Some of you may recall that in a <a href="http://lifeonanoxfordlawn.blogspot.com/2010/10/rotifer-genus-mniobia.html">recent posting</a> I bought a puddle into my house (it was in a plastic fishtank!). Well, I've hung on to my puddle. Indeed I've been periodically topping it up with fresh puddle-water and inspecting its inhabitants under my microscope. Photos 1 and 2 show two such 'denizens of the deeps'. No, not frog or toad spawn. The scale is all wrong for that. Twenty of the larger spheres in photo 2 for example, would sit side-by-side in 1mm. In fact these are of colonies of blue-green algae (<span style="font-style: italic;">cyanobacteria</span>).<br />
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Cyanobacteria are some of the most ancient lifeforms of all. Their microfossil record goes back 2.7 billion years. What I have learnt about them has been mostly through reading a new book - Phycology (=the study of algae) by R.E.Lee (CambridgeUni. Press) - which Santa very kindly delivered to me recently.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhEfp8qyWKr39roF2PjgvWQFqTYzBNJcEWBcNB7gk07kvF8-ygyjN9AJEEo1_jcAbb9Yj2GFJc6Jnhn0uTRiLeHIjmOh03y2Y9SayObNGptDeoGy_SeXzOxCFG8WZkfnD-QtI9USMlyc_t0/s1600/Cyanobacteria+possible+Nostoc+commune.jpg" onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}"><img alt="" border="0" id="BLOGGER_PHOTO_ID_5556604415567838562" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhEfp8qyWKr39roF2PjgvWQFqTYzBNJcEWBcNB7gk07kvF8-ygyjN9AJEEo1_jcAbb9Yj2GFJc6Jnhn0uTRiLeHIjmOh03y2Y9SayObNGptDeoGy_SeXzOxCFG8WZkfnD-QtI9USMlyc_t0/s320/Cyanobacteria+possible+Nostoc+commune.jpg" style="cursor: pointer; float: left; height: 240px; margin: 0pt 10px 10px 0pt; width: 320px;" /></a>Like plants, cyanobacteria carry out photosynthesis. In fact, it is believed that photosynthesis evolved first in cyanobacteria and at some point in the ancient past a cell that was to become the first plant 'swallowed' (co-opted) a cyanobacterium. Chloroplasts, the green organelles responsible for photosynthesis found inside all plant cells are the remnants of these 'swallowed' cyanobacteria.<br />
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Today such photosynthetic 'slavery' still persists in the lichens. About 10% of lichens use cyanobacteria to do their photosynthesis (the other 90% use algae).<br />
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Photosynthesisis is not the only chemical magic that cyanobacteria have mastered. They are also able to 'fix' nitrogen - that is take nitrogen gas from the air and turn it into an amino acid (glutamate). No higher plants or animals can do this, and a range of plants have formed symbiotic relationships with cyanobacteria to take advantage of this ability. Some plants have special nodules on their roots to house colonies of cyanobacteria. The water fern <span style="font-style: italic;">Azolla </span>has cavities in the leaves. According to the book above, nitrogen fixation by cyanobacteria also plays a fundamental role in keeping the world's 100million square km of paddy fields fertile in areas where otherwise farmers would be too poor to nitrogen-fertilise the soil.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2PMQn9GI_Lmwote8wbcxHtd5Fwl52Nl2cq1yruQNvAXGYPB7vRPcMXsbCc5RIPRvFuBzjgvnjAOm8xOe9KyaUx_lbnWgIXHDl7hU5LbNu0PvHlWg2lM1mZM3cEahmEy5sZfa0wzrSEbu5/s1600/Stromatolites_in_Sharkbay.jpg" onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}"><img alt="" border="0" id="BLOGGER_PHOTO_ID_5557536656533850850" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2PMQn9GI_Lmwote8wbcxHtd5Fwl52Nl2cq1yruQNvAXGYPB7vRPcMXsbCc5RIPRvFuBzjgvnjAOm8xOe9KyaUx_lbnWgIXHDl7hU5LbNu0PvHlWg2lM1mZM3cEahmEy5sZfa0wzrSEbu5/s200/Stromatolites_in_Sharkbay.jpg" style="cursor: pointer; float: left; height: 149px; margin: 0pt 10px 10px 0pt; width: 200px;" /></a>The twin ability of cyanobacteria to remove nitrogen and carbon dioxide from the atmosphere had a profound affect on the earth's early climate. Over eons, cyanobacteria, as the dominant lifeform at the time, transformed an ancient atmosphere rich in CO2 and almost devoid of oxygen into the one we breathe today. A glimpse of what the ancient earth might have looked like can be seen today at Shark's Bay in Australia where warm and salty waters limit other forms of life and allow cyanobacteria to dominate and grow into large, rocky (actually calcium carbonate) colonies called <span style="font-style: italic;">stromatolites </span>- see photo 3 which I'm using under the terms of the Wikimedia free licence. Stromatolites grow slowly and exhibit 'growth ring' like features. Analysis of these has allowed scientists to determine that for example, 1-billion years ago the earth's year comprised 435 days <a href="http://www.geol.ucsb.edu/faculty/awramik/pubs/VANY8521.pdf">[1]</a>.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiBIivP3XYNH0hAR3tWf1nCJUgqLko29qpAE-PenoO4Vzmr9fJnqrT1VDhJ3Phlqaweuy0-cLkLrp_3a-_GmOzFCfkMUtb5urLF9-EM1QJuusdnCCr5TcX2WVEoXNl5WqEGBFsrBD4CEWr2/s1600/Cyanobacteria+akinete+heterocyst.jpg" onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}"><img alt="" border="0" id="BLOGGER_PHOTO_ID_5557617111358818466" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiBIivP3XYNH0hAR3tWf1nCJUgqLko29qpAE-PenoO4Vzmr9fJnqrT1VDhJ3Phlqaweuy0-cLkLrp_3a-_GmOzFCfkMUtb5urLF9-EM1QJuusdnCCr5TcX2WVEoXNl5WqEGBFsrBD4CEWr2/s320/Cyanobacteria+akinete+heterocyst.jpg" style="cursor: pointer; float: left; height: 214px; margin: 0pt 10px 10px 0pt; width: 320px;" /></a>So, how do you set about identifying the species of a cyanobacterium? The answer is: with difficulty! Like so many areas of biology at present, DNA analysis is over-turning a lot of old species definitions. Things are further complicated by the fact that the appearance (morphology) of a specimen of a cyanobacterium can depend strongly on the conditions in which it has grown. Nevertheless with a little patience it's possible for the amateur (me!) to make a little progress. I've also been fortunate in having been able to borrow a copy of the hefty The Freshwater Algal Flora of the British Isles (Whitton and Brook). Firstly you need to know you're looking at a cyanobacterium. If the cells you're examining show any significant internal structure (especially a nucleus) then it's not a cyanobacterium, and is instead a true algae. Next one needs to take careful note of the detailed shape of the colony. For example, if your cyanobacteria exhibit chain-like growth its important to note whether the filaments branch, whether or not they taper towards the ends and whether or not the cells are encased in any sort of slimy envelope (as they are in photo 2). These features help separate the main genuses. Finally, it's important to note the presence and form of any <span style="font-style: italic;">heterocysts </span>and <span style="font-style: italic;">akinetes</span>. I've labelled these in photo 4. <span style="font-style: italic;">Heterocysts </span>are specialised, largely colourless cells that carry out nitrogen fixation. My impression from the textbooks is that the role of <span style="font-style: italic;">akinetes </span>is a bit of mystery. They have reduced photosynthetic ability and seem to be involved in food storage. Anyway based on these features and Whitton and Brook's book above I'm tentatively identifying my cyanobacteria as <span style="font-style: italic;">Anabaena cylindrica</span> and <span style="font-style: italic;">Nostoc commune</span>. As always I'm happy for anyone out there to correct me.<br />
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Finally, one of the most amazing things I learnt about cyanobacteria is the way in which some of them achieve movement. Some species develop tiny gas bubbles (vacuoles) inside the cells that help them float upwards in water to receive more sunlight. More fantastically some species can undertake a form of movement known as <span style="font-style: italic;">gliding</span>. Here the surface of the cells is sculptured in a series of grooves. The grooves may spiral around along a chain of cells. The cell pumps slime into the grooves through tiny pores. If a chain of cells is close to a surface, the flow of slime pushes against the surface and causes the whole filament to glide along over the surface at up to half a mm per second. Hooray for slime power!<br />
<br />
Reference<br />
[1] J.P. VANYO, S.M. AWRAMIK Precambrian Research, 29 ( 1985 ) 121-142, STROMATOLITES AND EARTH-SUN-MOON DYNAMICS,Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com2tag:blogger.com,1999:blog-2834972773043127807.post-10659899211002851142010-12-23T09:29:00.034+00:002010-12-29T20:27:38.910+00:00A fungus gnat , Sciarida (possibly Bradysia)I am an amateur naturalist trying to learn something about everything living in my garden.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhlXGXlgMJMv5e-xI3Qjkp6i-2F2_1gJkzZhE2mIe7TKyy4m5XCuff2Yf8CCtZUahafn9xvX6fR_FKA35dRMSJm1zfyflcsvE1zWskjVWh3PhM41t_vo7YgrkAm1-01gmTloQJ7vd3yM_Ro/s1600/sciard+fly+possibly+Bradysia.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 400px; height: 300px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhlXGXlgMJMv5e-xI3Qjkp6i-2F2_1gJkzZhE2mIe7TKyy4m5XCuff2Yf8CCtZUahafn9xvX6fR_FKA35dRMSJm1zfyflcsvE1zWskjVWh3PhM41t_vo7YgrkAm1-01gmTloQJ7vd3yM_Ro/s400/sciard+fly+possibly+Bradysia.jpg" alt="" id="BLOGGER_PHOTO_ID_5553933578192269922" border="0" /></a>Buoyed up by my successful (?!) identification of a fly to species level in my previous posting, today I'm taking on a related, though tougher challenge: the little gnat in photo 1 (click on photo's to enlarge). This one was around in my garden mid-May last.<br /><br />As I've discovered through writing this blog, to stand any real chance of identifying the smaller insects it's pretty much essential to have a microscope. This needn't cost the earth. Photo 1 was taken by holding a 'point and click' digital camera up to the eyepiece of a sub-£100 'DM2' stereo microscope. With 10x and 20x eyepieces this would probably suffice for a fair range of the needs of many amatuer naturalists though if you want to study the more minute structures such as mushroom spores, or the smaller pondlife, a microscope capable of 1000x magnification is needed. I have a (sub-£200) Westbury SP2 microscope which I've found to be thoroughly adequate for all my needs (the only minor drawback, for those in-the-know about such things, is I'm not certain this particular scope has the option to be equipped for 'dark field' operation, though this is a 'luxury' rather than a 'staple'). For anyone considering making a purchase, I have always been very satisfied with the service from <a href="http://www.brunelmicroscopes.co.uk/index.html">Brunel Microscopes Ltd </a>(I am unconnected with the company, and have received no payments for plugging them here!).<br /><br />To set about identifying my fly I turned first to "A Key to the families of British Diptera" by D.M.. Unwin, available free <a href="http://www.field-studies-council.org/fieldstudies/category/terrestrial.htm">here</a>. This is designed specifically with the amateur in mind, being copiously illustrated to explain any technical terms. There are more than 80 families of British fly. The fact that my fly has long, thread-like, multi-segmented antennae immediately rules out more than 5o of these however, and places my fly in the <span style="font-style: italic;">nematocera</span>, a sub-order of around 30 families. To distinguish between these its necessary, in part, to carefully examine your fly's wing. In my <a href="http://lifeonanoxfordlawn.blogspot.com/2010/12/crane-fly-in-family-limonia-nebeculosa.html">last posting</a> on a crane fly I discussed the prehistoric origins of fly wings and the so-called 'Comstock-Needham' code for labelling up their veins. I'll not repeat this here and simply point out that I've labelled up the wing veins in photo 1.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEipkVOWcTkJHyb60MNtz6BZ1T7rCvjQZ0yMFU-ZWqSJSbHDT7DU2fNCX_Y2z0e-yPc4tEwTPPBJ0-kJN4gNCH7VEd9vaC7uQ4xG7taL7w9fbNvoDRGLfUA3Agc7Q3db6htu_n8K6PAqIFsd/s1600/Eye+bridge+of+sciarid+fly+possibly+Bradysia.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 320px; height: 240px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEipkVOWcTkJHyb60MNtz6BZ1T7rCvjQZ0yMFU-ZWqSJSbHDT7DU2fNCX_Y2z0e-yPc4tEwTPPBJ0-kJN4gNCH7VEd9vaC7uQ4xG7taL7w9fbNvoDRGLfUA3Agc7Q3db6htu_n8K6PAqIFsd/s320/Eye+bridge+of+sciarid+fly+possibly+Bradysia.jpg" alt="" id="BLOGGER_PHOTO_ID_5553951334443521090" border="0" /></a>With the wings of my fly in view, the key above pretty quickly bought me to a choice of my gnat being in one of two families: the <span style="font-style: italic;">Sciaridae</span> or the <span style="font-style: italic;">Mycetophilidae</span>. The 'decider' was the eyes. Photo 2 (taken from above looking directly down onto the antennae) shows my fly's 'left' and 'right' eyes, though this is a rather arbitrary choice of words since in fact the eyes are joined together to form one continuous band above the antennae. If ever you wanted an example of how 'alien' is the world of insects' senses, surely having eyes that join on top of you're head is one! Anyway, this 'eye bridge' decides against my fly being in the <span style="font-style: italic;">Mycetophildae</span> and makes it a member of the <span style="font-style: italic;">Sciaridae</span>. In searching for information on sciarid flies I came across two useful websites, the <a href="http://sciaroidea.info/">first</a> dedicated to Sciariod flies, and <a href="http://www.online-keys.net/news.php">the second</a>, a list of free, online keys to different diptera.<br /><br />The Sciarid flies are sometimes called 'fungus gnats', mushrooms being the larval food for some species. Mushrooms are not the only food however, and species have been reported emerging from a wide variety of substances from dead animals to birds' nests. Perhaps the most amazing thing I learnt about Sciarids in a short time searching is that the larvae of some occasionally undergo mass movements, thousands of them marching in columns several centimetres wide and metres long. I found an online paper reporting one such movement <a href="http://psyche.entclub.org/58/58-073.html">here</a> [1]. It seems no one knows why they do this.<br /><br />So far so good! Unfortunately, whilst identifying a fly to family level (<span style="font-style: italic;">Sciaridae </span>in this case) is generally tractable, getting much further can be decidedly tricky. The first problem is that there are a lot of families of fly and finding a text-book or key that deals with yours can be difficult or indeed impossible. As luck would have it however, having become interested in flies and having something of a passion for natural history books, last summer I treated myself to some of the Handbooks for the Identification of British Insects from the <a href="http://www.royensoc.co.uk/publications/index.htm">Royal Entomological Society</a>, amongst them <span style="font-style: italic;">Sciarid Flies</span> by P. Freeman.<br /><br />The book starts a little ominously:<br /><br /><span style="font-style: italic;">[Sciard] taxonomy has always presented problems [...] the student has always been faced with a mass of similar looking species which he has been unable to group adequately. </span><br /><br />Fortunately Freeman's book provides a detailed guide to identification, covering about half (according to <a href="http://www.online-keys.net/sciaroidea/2000_/Menzel_et_al_2006_Sciaridae_sp_n_checklist_GB.pdf">this paper</a> [2], as of 2005 there were 263 species of British <span style="font-style: italic;">Sciaridae </span>in total) the British species across 18 genera.<br /><br />So how did I get on sifting through the 18 genera of <span style="font-style: italic;">Sciaridae </span>in Dr. Freeman's key? Well, On the basis of wing-vein shape and length, I was able to rule out 4 of the 18 genera; There was no sign of largish hairs ('macrotrichia') on my fly's wing veins, though there were tiny, downy hairs ( 'microtrichia'). This rules out another 5 genera; My fly has tiny spurs on its leg tibia (see photo 1). These are not <span style="font-style: italic;">'distrinctly longer than the width of the tibia'</span>, ruling out the genus <!--[if gte mso 9]><xml> <w:worddocument> <w:view>Normal</w:View> <w:zoom>0</w:Zoom> <w:punctuationkerning/> <w:validateagainstschemas/> <w:saveifxmlinvalid>false</w:SaveIfXMLInvalid> <w:ignoremixedcontent>false</w:IgnoreMixedContent> <w:alwaysshowplaceholdertext>false</w:AlwaysShowPlaceholderText> <w:compatibility> <w:breakwrappedtables/> <w:snaptogridincell/> <w:wraptextwithpunct/> <w:useasianbreakrules/> <w:dontgrowautofit/> <w:usefelayout/> </w:Compatibility> <w:browserlevel>MicrosoftInternetExplorer4</w:BrowserLevel> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:latentstyles deflockedstate="false" latentstylecount="156"> </w:LatentStyles> </xml><![endif]--><!--[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} </style> <![endif]--><i style="">Corynoptera. </i>After a little further work I was down to a choice between the genus <span style="font-style: italic;">Bradysia </span>and the genus <span style="font-style: italic;">Lycoriella</span>...and...I dropped my fly on the floor and lost it!!! On the basis of a couple of half-examined features, and the fact that <span style="font-style: italic;">Bradysia </span>is the larger, more common genus, I'm going for <span style="font-style: italic;">Bradysia</span>. But it all goes to show - you can't win 'em all!<br /><br /><span class="authors">Reference<br />[1] C. T. Brues, </span><span class="title">A Migrating Army of Sciarid Larvae in the Philippines<span style="font-style: italic;">, </span></span><span class="citation"><i>Psyche </i><strong>58</strong>:73-76, 1951</span>.<br /><br />[2] Zoological Journal of the Linnean Society, 2006,146, 1–147. The sciarid fauna of the British Isles (Diptera: Sciaridae), including descriptions of six new species Frank Menzel, Jane E. Smith and Peter J. ChandlerHenry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com2tag:blogger.com,1999:blog-2834972773043127807.post-36157281469015240122010-12-20T15:02:00.056+00:002010-12-21T20:37:41.305+00:00A crane fly Limonia nebeculosaI am an amateur naturalist trying to learn something about everything living in my garden.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCECDR_9TbeUtbxAPalcngJMwhzwtoJtAiT2ELmqH2B88PsflHp0tPkkD0IYvVfNKQVVFKR8rqRVQqmnJjQJLHyPl3trDuVo7HLUIgh3ejXcCY78DBYlfJ2QLz2DGZibQj6V-qhEHnQNvl/s1600/Limonia+nebeculosa+crane+fly.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 320px; height: 214px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCECDR_9TbeUtbxAPalcngJMwhzwtoJtAiT2ELmqH2B88PsflHp0tPkkD0IYvVfNKQVVFKR8rqRVQqmnJjQJLHyPl3trDuVo7HLUIgh3ejXcCY78DBYlfJ2QLz2DGZibQj6V-qhEHnQNvl/s320/Limonia+nebeculosa+crane+fly.jpg" alt="" id="BLOGGER_PHOTO_ID_5553220597115931874" border="0" /></a>My garden, along with the rest of the UK, is currently buried beneath a thick blanket of snow. Aside from a collection of tits on my bird feeder there's little sign of life. For this posting therefore, I'm falling back to a photo of a crane fly I took in summer (photo 1. Click on photo's to enlarge). Dozens of them swarmed out from amongst some <a href="http://lifeonanoxfordlawn.blogspot.com/2007/02/ivy-hedera-helix.html">garden ivy</a> I happened to disturb at the time.<br /><br />I know almost nothing about flies (diptera). Along with <a href="http://lifeonanoxfordlawn.blogspot.com/2007/05/beetle-in-family-carabidae.html">beetles</a>, <a href="http://lifeonanoxfordlawn.blogspot.com/2010/09/ichneumon-wasp-amblyteles-armatorius.html">ichneumon wasps</a> and various other orders of insect however, they strike me as offering rather "good value" to any amateur naturalist keen to make a genuine contribution to science since a) there are very large numbers of them (15,000 species of fly in Europe alone) b) they can display a rich and complex behaviour (see my<a href="http://lifeonanoxfordlawn.blogspot.com/2010/04/signalling-fly-poecilobothrus.html"> posting</a> on <span style="font-style: italic;">P. nobilitatus</span> for example) and c) for countless species almost nothing is known. Take hoverflies for example. After hundreds of years of intense study by armies of naturalists there can be few countries in the world whose natural history has been so well catalogued as Britain's. Further, there are few flies as conspicuous as hoverflies. Yet even for these, a staggering 40% of the larvae of the 265 British hoverfly species of are simply unknown. In the U.S. its 93%. (This, at least, was the situation persisting in 1993 when my copy of 'Colour Guide to Hoverfly Larvae' (G.E.Rotheray) was published). Anyway, we're not here to discuss hoverflies. On to the star of today's show...<br /><br />What makes a crane fly a crane fly? Well, firstly flies (=the<span> order</span><span style="font-style: italic;"> diptera</span>) are separated from <a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiImphPsgP97UwtVWVUHMi2PjRM1FGiNd5wKFchu9O292gb1IkZav4WGdCAi1EpLhS4Q3iwoTybI7wbZZEmUQIOfty-z7pJ-EHq13TaFfUjnb6Zu9_8L8gE-swZQ0Am7TC0sOfM7QprslPR/s1600/Limonia+nebeculosa+crane+fly+haltares.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 200px; height: 150px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiImphPsgP97UwtVWVUHMi2PjRM1FGiNd5wKFchu9O292gb1IkZav4WGdCAi1EpLhS4Q3iwoTybI7wbZZEmUQIOfty-z7pJ-EHq13TaFfUjnb6Zu9_8L8gE-swZQ0Am7TC0sOfM7QprslPR/s200/Limonia+nebeculosa+crane+fly+haltares.jpg" alt="" id="BLOGGER_PHOTO_ID_5553224382474275954" border="0" /></a>other insects by the presence of two vestigial wings called <span style="font-style: italic;">halteres</span>. I've ringed these in photo 2. Next, the order <span style="font-style: italic;">diptera </span>is separated into two <span style="font-style: italic;">sub-orders </span><span>of flies</span> called the <span style="font-style: italic;">nematocera </span>and the <span style="font-style: italic;">brachycera</span>. The split is based on the structure of the antennae - the <span style="font-style: italic;">nematocera </span>all have long, thread-like antennae with more than five segments. You can see this in photo 3. The sub-order <span style="font-style: italic;">nematocera </span>gets further subdivided into more than 70 <span style="font-style: italic;">families<span style="font-style: italic;"> </span></span>of fly, the crane flies amongst them. If you want a fuller flavour of how these families are separated, the redoubtable Field Studies Council has made a key to the families of fly by D.M. Unwin <a href="http://www.field-studies-council.org/fieldstudies/category/terrestrial.htm">freely available here</a>.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiKXfLSJ74NsSp7QQ-mPXiNpIjiDuOWvqKzAn8TiT7LTToJpxzjie68dlgM9M6huGc29aTZOFQNDd3Wg_6BA8f24TV82wg6YRYWUwpvzqMFrbRIisoJ5wxubFfHlRXokg661kCvD16CGgx7/s1600/Limonia+nebeculosa+crane+fly+antennae.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 200px; height: 173px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiKXfLSJ74NsSp7QQ-mPXiNpIjiDuOWvqKzAn8TiT7LTToJpxzjie68dlgM9M6huGc29aTZOFQNDd3Wg_6BA8f24TV82wg6YRYWUwpvzqMFrbRIisoJ5wxubFfHlRXokg661kCvD16CGgx7/s200/Limonia+nebeculosa+crane+fly+antennae.jpg" alt="" id="BLOGGER_PHOTO_ID_5553222909674832962" border="0" /></a>It used to be that all crane flies were clumped together in one family<span style="font-style: italic;"> </span>called the <span style="font-style: italic;">Tipulidae</span>. At some point however it was decided to split this family into four, the <span style="font-style: italic;">Tipulidae,</span> <span style="font-style: italic;">Pediciidae</span>, <span style="font-style: italic;">Limoniidae </span>and the <span style="font-style: italic;">Cylindrotomidae</span>. I read on the (searchable) <a href="http://ip30.eti.uva.nl/ccw/stats.php">Catalog of the Craneflies of the World</a> that worldwide there are more than 10,000 species of <span style="font-style: italic;">Limoniidae</span>, 4000 <span style="font-style: italic;">Tipulidae</span> nearly 500 <span style="font-style: italic;">Pediciidea </span>and 70-odd <span style="font-style: italic;">Cylindrotomidae</span>. Separating these families is a tricky job. To complicate matters further, recent DNA studies [2] are casting doubt on the very existence of the <span style="font-style: italic;">Limoniidae </span>as a family.<br /><br />The whole thing is rather confusing for the amateur (=me!) and for a long time whilst preparing this posting I despaired of being able to identify my crane fly. Fortunately, rescue was at hand in the form of an excellent set of <a href="http://www.dipteristsforum.org.uk/t464-Draft-keys-Craneflies.html">test keys from Alan Stubbs</a> I found on the Dipterists Forum website.<br /><br />Before discussing these keys I need say something about how dipterists characterise the wings of flies: An influential theory, originally due to Comstock and Needham in the 1890's, is that way back in prehistory, a first primeval insect wing evolved. Exactly how this first wing appeared is still uncertain but a <a href="http://www.imbb.forth.gr/people/averof/Nature97w.pdf">current theory</a> [1] is that it evolved from the multi-branched external gills seen on the larvae of some aquatic insects such as mayflies. The veins in insect wings are hypothesised to be modifications of these gill 'tubes' (<span style="font-style: italic;">trachea</span>). Anyway, assuming the existence of this ancestral wing, Comstock and Needham named<span> the veins in it<span style="font-style: italic;"><span style="font-style: italic;"> </span></span>the Costa (C), the Radius (R), the Media (M), the Cubitus (Cu) and the Anal veins (A). As these veins fanned out through the ancestral wing they forked. So, for example, the radius vein, </span><span>R, is supposed to have forked into five sub-veins called (logically enough) R1 to R5. </span>No modern fly has retained all the veins of the ancestral wing, over millenia evolution has caused different families of fly to lose different veins. Which veins a fly has retained however is a very important clue to its identification.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh0uNNbYVrlnt0heYeFU0m6-sxu8DNoFdBMlioluRDXf-PATz2yIa3lasGZix4TULirbEc_N-0Zv8201E6AkMoD8d5j-3ezTGox-d797fMQTBPuHWs73PSl-YcoTc1BqUcM0s_7rKQ9puXx/s1600/Limonia+nebeculosa+wing.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 320px; height: 218px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh0uNNbYVrlnt0heYeFU0m6-sxu8DNoFdBMlioluRDXf-PATz2yIa3lasGZix4TULirbEc_N-0Zv8201E6AkMoD8d5j-3ezTGox-d797fMQTBPuHWs73PSl-YcoTc1BqUcM0s_7rKQ9puXx/s320/Limonia+nebeculosa+wing.jpg" alt="" id="BLOGGER_PHOTO_ID_5553220038943005570" border="0" /></a>Photo 4 shows the wing of my crane fly labelled up with the help of Alan Stubbs' keys above according to the Comstock Needham system.<br /><br />There was one more piece of information I needed, namely whether my crane fly's palps (=little facial apendages) were long or short. Photo 5 shows they're short.<br /><br />Armed with this information I was finally able to identify my cranefly as <span style="font-style: italic;">Limonia nebeculosa</span>. Final 'clinchers' were the presence of 3-coloured bands on my fly's femurs (enlarge to see these in photo 1) and the sort of smudgy 'hoop' on the wing I've delineated with the dashed white line in photo 4.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiT8bDH0GowjIU1Ss1KbEGN835kOjipTRtVp1ld5gyFSdLyECHyDti_G2lc514bStB6igI8OOa6Cwct9xRbuToQtiSErq9dWEcB3LPX6idXmvapZd77Pmkb2CMN5Big57GYPj1qjFiAKR7W/s1600/Limonia+nebeculosa+palp.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 200px; height: 172px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiT8bDH0GowjIU1Ss1KbEGN835kOjipTRtVp1ld5gyFSdLyECHyDti_G2lc514bStB6igI8OOa6Cwct9xRbuToQtiSErq9dWEcB3LPX6idXmvapZd77Pmkb2CMN5Big57GYPj1qjFiAKR7W/s200/Limonia+nebeculosa+palp.jpg" alt="" id="BLOGGER_PHOTO_ID_5553229169142431266" border="0" /></a>Today's posting was a bit technical in places but I am pleased to have identified my first fly to species level. Only another 250,000 to go!<br /><br />References<br /><br />[1] Averof M., Cohen S.M., <span style="font-style: italic;">Nature</span> 385, 627-630, 1997 <span style="font-style: italic;">Evolutionary origin of insect wings from ancestral gills.</span><br /><br />[2] Matthew J., <span style="font-style: italic;">et.al.</span> <span style="font-style: italic;">Phylogenetic synthesis of morphological and molecular</span> <span style="font-style: italic;">data reveals new insights into the higher-level</span><span style="font-style: italic;"> classification of Tipuloidea (Diptera),</span> Systematic Entomology (2010), DOI: 10.1111/j.1365-3113.2010.00524.xHenry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com2tag:blogger.com,1999:blog-2834972773043127807.post-17966919780089999432010-12-11T15:15:00.028+00:002010-12-11T23:25:43.821+00:00A lichen Malanelia subauriferaI am an amatuer naturalist trying to learn something about everything living in my garden.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjC3xBfIx00baRzMUvGlYGSc4qWgYiE6zQQftePAsjA1xVRx6j9RB0zI2I3-Jo0t_8J4_TJ7B961w0xaeihjPpVvhh1Tkhbr6BQl173vELY-WXSDE1ESeqANC5X8BRycdY5Focu2IcJm3pV/s1600/Melanelia+subaurifera+lichen.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 400px; height: 267px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjC3xBfIx00baRzMUvGlYGSc4qWgYiE6zQQftePAsjA1xVRx6j9RB0zI2I3-Jo0t_8J4_TJ7B961w0xaeihjPpVvhh1Tkhbr6BQl173vELY-WXSDE1ESeqANC5X8BRycdY5Focu2IcJm3pV/s400/Melanelia+subaurifera+lichen.jpg" alt="" id="BLOGGER_PHOTO_ID_5549449073132954530" border="0" /></a>Photo 1 shows a lichen growing, amongst a number of similar patches, on a wooden bird table in my garden.<br /><br />I am very far from being an expert on lichen identification but in the course of doing this blog over several years I have picked up a few tricks. One is to examine your lichen through a hand lens for any characteristic surface lumps on bumps. Some lichen species become decorated with powdery granules called soralia. Others with tiny sausage shaped protuberances called isidia. For my lichen, the latter are present in abundance as can be seen in the close-up Photo <a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdeURjKG9ml6fLEsk9-YMJk-FAPxZOfIbN0oF1-6ikrWm2ECgDlaLYoAWq7G1xOlazs27DsleplSzLWcBqCvAylTz87ePHLpBiJYrkeEzcoNJ2_wczKfHAIIPERT1pxVmcXUU_vw05e96n/s1600/Melanelia+subaurifera+isidia.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 320px; height: 213px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdeURjKG9ml6fLEsk9-YMJk-FAPxZOfIbN0oF1-6ikrWm2ECgDlaLYoAWq7G1xOlazs27DsleplSzLWcBqCvAylTz87ePHLpBiJYrkeEzcoNJ2_wczKfHAIIPERT1pxVmcXUU_vw05e96n/s320/Melanelia+subaurifera+isidia.jpg" alt="" id="BLOGGER_PHOTO_ID_5549450789758146530" border="0" /></a>2 (click on photos to enlarge).<br /><br />Another trick to help with lichen identification is to check the under surface. In photo 2 I have peeled back a small section to reveal a black underside with a covering of tiny, root-like hairs. In the jargon, these are known as <span style="font-style: italic;">rhizines</span>. Not all lichens have them. They are not roots in the traditional sense, since <a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiADfgwlLftpAB_fwo5I1wKxmQ9suLneLwoCD2jGFEcLQngGP-ceNZm58GOnD1JGgBlJJI0z8AxMWnKdTPUzn9xxfllhTz9lQ85aaKYfzkPRZQhyphenhyphenovfhxuc838wsXZ6UlHBUgRL8mlWI_rr/s1600/Melanelia+subaurifera+underside+rhizines.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 320px; height: 214px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiADfgwlLftpAB_fwo5I1wKxmQ9suLneLwoCD2jGFEcLQngGP-ceNZm58GOnD1JGgBlJJI0z8AxMWnKdTPUzn9xxfllhTz9lQ85aaKYfzkPRZQhyphenhyphenovfhxuc838wsXZ6UlHBUgRL8mlWI_rr/s320/Melanelia+subaurifera+underside+rhizines.jpg" alt="" id="BLOGGER_PHOTO_ID_5549451130979402946" border="0" /></a>they do not function to suck-up water as do the roots of plants. Rather their job seems to be to help anchor lichens to surfaces.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEio4PvhSU0b6vDyQwxxyIJHpQiu2RfNWb2OOa7yBvwcniRSibT01celBIXj0AZpGQAq7xp6I9cmkEjK-cTGXOw_BbATPRrSiR7Kpzp2SfEnBR47BbVT5H7SXYUtzEnUt6jQvHJeV7mqP0zL/s1600/Melanelia+subaurifera+rubbed.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 200px; height: 134px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEio4PvhSU0b6vDyQwxxyIJHpQiu2RfNWb2OOa7yBvwcniRSibT01celBIXj0AZpGQAq7xp6I9cmkEjK-cTGXOw_BbATPRrSiR7Kpzp2SfEnBR47BbVT5H7SXYUtzEnUt6jQvHJeV7mqP0zL/s200/Melanelia+subaurifera+rubbed.jpg" alt="" id="BLOGGER_PHOTO_ID_5549454084110423586" border="0" /></a>Armed with the features above and my trusty copy of Lichens (Dobson, Richmond Publishing) I'm confident to identify my lichen as <span style="font-style: italic;">Melanelia (Parmelia) subaurifera</span>. The book suggests a final test: gently rubbing the surface should leave a pale yellow-white abrasion. Photo 4 shows this.<br /><br />I am fond of lichens and so was very pleased when someone recently made me a present of the new edition of Lichen Biology (Ed. Thomas H Nash III, publ. Cambridge). This book is primarily aimed at professionals and I don't pretend to have followed some of the very detailed sections on e.g. lichen biochemistry, but I was able to follow others and came away with a new respect for the intricacy with which nature adapts these little creatures to their environment. Take for example the construction of the little air-filled spaces often found inside the bodies of lichens:<br /><br /> Under a microscope a lichen is revealed to be a mass of long, spaghetti-like fungal cells ('<span style="font-style: italic;">hyphae</span>'), mixed-through with a sprinkling of green, single-celled algae or sometimes cyanobacteria. (The fungus carries out various tasks such as water storage. The algae or cyanbacteria do what no fungus can: photosynthesise food from sunlight). In considering this description however it would be wrong to picture things as a random tangle of fungal threads and algal cells. Photo 5 shows a lichen cross <a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiHMw404eWwH3yEGtLDTr_Em2_LF1jKU4CrRam4bBo-YsT2WbypHm1SMANMEy_kmKMmtrisNkDfYLWcIcXYmIQxRMgYDGEvylgyJiizJqoUeT3-WeGy_Lzm-f-85jNzRRjjG3NmYyfwNJOV/s1600/Xanthoria+parietina+apothecium+cross+section.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 320px; height: 214px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiHMw404eWwH3yEGtLDTr_Em2_LF1jKU4CrRam4bBo-YsT2WbypHm1SMANMEy_kmKMmtrisNkDfYLWcIcXYmIQxRMgYDGEvylgyJiizJqoUeT3-WeGy_Lzm-f-85jNzRRjjG3NmYyfwNJOV/s320/Xanthoria+parietina+apothecium+cross+section.jpg" alt="" id="BLOGGER_PHOTO_ID_5549484966124369410" border="0" /></a>section I made and discussed some time ago (<a href="http://lifeonanoxfordlawn.blogspot.com/2010/01/lichen-lecanora-dispersa.html">here</a>) and reveals that things are far from random. Of particular relevance for today's posting is the layer known as the <span style="font-style: italic;">medulla</span> that contains a lot of air-filled voids (see the region of the box in photo 5 for example). What is the purpose of these voids? The answer of course is that algae, like all plants, 'feed' (via photosynthesis) on a diet of sunlight and gaseous carbon dioxide. This is the key to understanding the voids: they are present to allow the flow of gaseous CO2 gas to the algae.<br /><br />So far so good, but possibly it might occur to you to wonder what happens when it rains?! Do these voids fill up with water and in so-doing stifle CO2 flow, and hence photosynthesis, in the lichen? As I learnt from the book above Nature, of course, has an answer. In one chapter, a remarkable photograph taken by Rosmarie Honeggar with an electron microscope reveals how the fungal threads in the medulla carefully coat themselves and their precious cargo of algal cells in a minuscule layer of water-repellent proteins. This remarkable water repellent 'jacket' prevents the medulla from becoming saturated with water and so maintains the algae in a gaseous environment conducive to photosynthesis.<br /><br />The water-repelling proteins the fungal hyphae secrete are known as <span style="font-style: italic;">hydrophobins </span>and their discussion would make a lengthy posting in its own right. They were unknown to science until the 1990's when they were discovered by Wessel and co-workers in a fungus called <span style="font-style: italic;">Schizophyllum commune</span>. Since their discovery these remarkable molecules have turned out to be widespread amongst fungi, with fungi using them in a variety of ingenious ways to 'manipulate' the surface tension of watery environments. For example, in order to help their spores get airborne, some plant-infecting fungi coat their spores in hydrophobins so as to prevent them becoming trapped or stuck together by thin films of water. Hydrophobins also help the infectious spores stick to the waxy, water-repellent leaves of targeted host plants. You can find a short introduction and further references on hydrophobins in lichens <a href="http://onlinelibrary.wiley.com/doi/10.1046/j.1469-8137.2002.00387.x/pdf">here</a> ( P.S. Dyer, New Phytologist (2002) 154 : 1–4).<br /><br />So there you have it! Minuscule, air-filled voids in a wafer-thin lichen...but take a closer look and as so often in natural history, one finds a hitherto unimagined world of subtlety and sophistication.Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com1tag:blogger.com,1999:blog-2834972773043127807.post-65687453838303519472010-12-04T16:53:00.011+00:002010-12-05T10:31:47.252+00:00Greater Plantain Plantago majorI am an amateur naturalist trying to learn something about everything living in my garden.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZnJMc3F4RSw3uLtwT_JCSHlxL1yRaWET9RHy_VVIwicaHdMri5jX1OeHZtTb9v14o2gu3MdqdZWyS2aW9CyA1vdVRRp3U_yTN549rWi5KDfOVxMeDEVm60d5pFxeqyYym5dDjF54Rudx5/s1600/Greater+Plantain+Plantago+major.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 267px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZnJMc3F4RSw3uLtwT_JCSHlxL1yRaWET9RHy_VVIwicaHdMri5jX1OeHZtTb9v14o2gu3MdqdZWyS2aW9CyA1vdVRRp3U_yTN549rWi5KDfOVxMeDEVm60d5pFxeqyYym5dDjF54Rudx5/s400/Greater+Plantain+Plantago+major.jpg" alt="" id="BLOGGER_PHOTO_ID_5546881856253057602" border="0" /></a>Taken in August, photo 1 shows a specimen of the weed Greater Plantain (<span style="font-style: italic;">Plantago major</span>) growing on my lawn. This plant is very common in the UK and likely to be encountered on any patch of rough wasteland (= my lawn!).<br /><br />For such a common plant I have found relatively few freely available papers dealing with Greater Plantain on the web. There are a number (such as <a href="http://www.fitoica.com/Biblioteca/Revistas/Journal%20of%20Etnopharmacology/2006/N1/3.pdf">here</a> and <a href="http://www.academicjournals.org/AJB/PDF/pdf2009/20Mar/Ozaslan%20et%20al.pdf">here</a>) that deal with its medicinal properties. <span style="font-style: italic;">Plantago major</span> appears to have a long list of antibacterial, antifungal and antitumeral properties and has even been recommended to treat the bites of rapid dogs! Amongst the interesting snippets I picked up from skimming the paper by <a href="http://www.fitoica.com/Biblioteca/Revistas/Journal%20of%20Etnopharmacology/2006/N1/3.pdf">Velaso-Lezama et.al.</a> [1] is that Greater Plantain is today used as a medicinal tonic in Mexico having been originally introduced there by the Spanish conquistadors.<br /><br />A number of species of Plantain grow in the UK including Ribwort- and Buck's Horn- , both of which have narrower ('lanceolate') leaves than Greater Plantain. Also Hoary Plantain (<span style="font-style: italic;">Plantago media</span>) which as the name implies differs from Greater Plantain in having greyish down on the leaves. That at least is how things are set out in my copy of The Wild Flower Key (F. Rose, publ. Warne). If however, the <span style="font-style: italic;">Plantago media</span> above is one and the same as the <span style="font-style: italic;">Plantago </span>inter<span style="font-style: italic;">media</span> described in <a href="http://www.watsonia.org.uk/Wats26p373.pdf">this paper</a> [2] by El-Bakatoucshi et.al., then these authors cast doubt on whether <span style="font-style: italic;">major</span> and <span style="font-style: italic;">intermedia</span> are sufficiently distinct to be regarded as separate (sub) species.<br /><br />In skimming the paper above by El-Bakatoucshi et.al. , a word I came across that was new for me was <span style="font-style: italic;">protogynous</span> (in context:<span style="font-style: italic;"> "Plantago major is protogynous"</span>). A little research and I now understand what this means. I'll share it here for interested readers: Firstly one has to recall that for many plants, the flower is typically neither male nor female. Rather the same flower combines male pollen producing parts (the anthers) and a female reproductive part (the stigma). This gives plants an issue of how to avoid self-fertilisation (i.e. self pollination). Plants have come up with a variety of solutions including i) Ignore the problem (= allow self pollination) ii) Separate your line into two, so that some plants carry only male and others only female parts (these are the so-called dioescious plants - from the Greek "two houses" . Our<a href="http://lifeonanoxfordlawn.blogspot.com/2007/11/stinging-nettle-urtica-dioica.html"> old friend</a> the stinging nettle is an example) iii) Develop some "chemical / structural" approach that avoids self pollination. I <a href="http://lifeonanoxfordlawn.blogspot.com/2007/02/primrose-primula-vulgaris.html">wrote about a classic example</a> when I discussed the two types of primrose, 'pin' and 'thrum' iv) Separate the <span style="font-style: italic;">time</span> at which the male and female parts of a flower are active / receptive. This latter method ('iv') is <span style="font-style: italic;">protogyny </span>and is the technique adopted by Greater Plantain. The female stigmas of Greater Plantain flower are protruded 1-3 days before pollen is produced and in this way the chances of self pollination are reduced. Another of those small but elegant behaviours Mother Nature has carrying on all around us.<br /><br />References<br />[1] <span style="font-style: italic;">Effect of Plantago major on cell proliferation in vitro</span> R. Velasco-Lezama et.al., Journal of Ethnopharmacology 103 (2006) 36–42<br /><br />[2] <span style="font-style: italic;">Introgression between Plantago major L. subspecies major and</span><br /><span style="font-style: italic;">subspecies intermedia (Gilib.) Lange. in a British population</span>, R. El-Bakatoushi et.al. , Watsonia 26: 373-379 (2007)Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com0tag:blogger.com,1999:blog-2834972773043127807.post-57779980614319247022010-10-13T21:47:00.044+01:002010-10-17T08:59:34.309+01:00Smooth Hawks-beard Crepis capillarisI am an amateur naturalist trying to learn something about everything living in my garden.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjDJ0_Igf0aPOo_hyphenhyphendLENRUSMsyCrh8DpYnIS-hG0z92-kk-RDnA0dUYK9f9jkDAveMByEw4yp2eAHGrdTMtjVkI56k2d5vFVLc-CTI9XsNKv3xeNM5STUbcXOhm43KJ-qrACs1P57Tqyj-/s1600/Smooth+Hawk%27s-beard+Crepis+capillaris.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 400px; height: 300px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjDJ0_Igf0aPOo_hyphenhyphendLENRUSMsyCrh8DpYnIS-hG0z92-kk-RDnA0dUYK9f9jkDAveMByEw4yp2eAHGrdTMtjVkI56k2d5vFVLc-CTI9XsNKv3xeNM5STUbcXOhm43KJ-qrACs1P57Tqyj-/s400/Smooth+Hawk%27s-beard+Crepis+capillaris.jpg" alt="" id="BLOGGER_PHOTO_ID_5527636065048984866" border="0" /></a>I have mentioned previously that the pleasure for me in maintaining this blog is that some previously unnoticed (by me at least) plant or insect, once researched, takes on a whole new aspect. So it is with today's posting. A scattering of facts about the genetics of an inauspicious weed may seem obscure to some, but for me, a weed on my lawn catches my eye with a new interest these days. Photos 1,2 and 3 shows said weed. It pops up frequently in my garden.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUhzs_2tqot9oHgVVCti0OifI3SRIxycilzxwR01vnRFFnqaeJ4uY58hcHSigL8L0onixy9TYV2wVTqMAhLpSlFwSJMuqulz07Hv69BEGYbVQ_gP1VHA22Q1C6bfWDP-hecUkSUn9I2Tg8/s1600/Smooth+Hawk%27s-beard+Crepis+capillaris+2.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 320px; height: 240px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUhzs_2tqot9oHgVVCti0OifI3SRIxycilzxwR01vnRFFnqaeJ4uY58hcHSigL8L0onixy9TYV2wVTqMAhLpSlFwSJMuqulz07Hv69BEGYbVQ_gP1VHA22Q1C6bfWDP-hecUkSUn9I2Tg8/s320/Smooth+Hawk%27s-beard+Crepis+capillaris+2.jpg" alt="" id="BLOGGER_PHOTO_ID_5528560652787723858" border="0" /></a>For the unskilled amateur botanist (=me!) identifying yellow flowered weeds isn't altogether trivial as the guide books contain a long lists of yellow-flowered ragworts, fleabanes, marigolds, colts-foots, dandelions, sowthistles, cats'-ears and hawkbits. After a little work however I'm fairly confident my plant is none of these and is instead Smooth Hawks-beard (<span style="font-style: italic;">Crepis capillaris</span>). A characteristic feature of the Hawks-beards are 'involucre bracts' (=the little leaves around the base of the flower head - best seem in photo 2) organised in distinct inner and outer rows.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3Na2PZoPly8qxYe9g7T9UF4dJ558H5HMYk-Apdwpb-TQT64AOYRroZketdxZ1IzvHQfiTTcHVrwRY7KJGNuwHkpvvBYMcE1ImV4-I-LJZx6BRDgctUZwrf2xEwWg8olRy8WXs4TnOJEcR/s1600/Snooth+Hawk%27s-beard+Crepis+capillaris+3.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 200px; height: 134px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3Na2PZoPly8qxYe9g7T9UF4dJ558H5HMYk-Apdwpb-TQT64AOYRroZketdxZ1IzvHQfiTTcHVrwRY7KJGNuwHkpvvBYMcE1ImV4-I-LJZx6BRDgctUZwrf2xEwWg8olRy8WXs4TnOJEcR/s200/Snooth+Hawk%27s-beard+Crepis+capillaris+3.jpg" alt="" id="BLOGGER_PHOTO_ID_5528585520771685906" border="0" /></a>Surprisingly, although it is a common UK weed, I've been able to find almost no detailed online information on Smooth Hawksbeard. One exception is the <a href="http://www.bioimages.org.uk/html/t1078.htm">bioimages site</a> that lists a handful of fungal rusts (including some <span style="font-style: italic;">Puccinia </span>species - see my post <a href="http://lifeonanoxfordlawn.blogspot.com/2007/06/fungal-rust-puccinia-lagenophorae.html">here</a>) and a gall fly known to parasitise Hawksbeard. The other exception was an <a href="http://jcs.biologists.org/cgi/reprint/92/3/329.pdf">online paper by Oud et.al. </a>[1] that describes the chromosomes of <span style="font-style: italic;">C. capillaris</span>. With my comments of the opening paragraph above in mind, its this I'll discuss.<br /><br />As most people know, the DNA inside cells is packaged into structure called chromosomes. When new cells are needed by a body, the existing cells set about creating copies of themselves by dividing into two, in a process known as <span style="font-style: italic;">meitosis. </span>(Cells destined to become specialist structures such as sperm or eggs do something slightly different called <span style="font-style: italic;">meiosis</span>, but never mind that here). To create two cells from one its clearly necessary to replicate the DNA. To do this the chromosomes perform a complex little 'dance' inside the cell in which they double in number (in a process called <span style="font-style: italic;">interphase</span>), pair up and line up along of the middle of the cell ('<span style="font-style: italic;">prophase</span>' and '<span style="font-style: italic;">metaphase</span>' respectively) and finally split apart ('<span style="font-style: italic;">anaphase</span>') as the cell separates into two ('<span style="font-style: italic;">telophase</span>').<br /><br />I got the hang of this terminology recently using my colouring crayons! (I've a copy of the very clever - '<span style="font-style: italic;">The Botany Colouring Book'</span>, Young - in which you learn by doing). You can find any number of explanations on the web however <a href="http://en.wikipedia.org/wiki/Mitosis">(here</a> for example).<br /><br />It's perfectly possible to watch the whole miraculous 'chromosomal dance' down a hobbyists microscope. The classic place to look is at the growing tip of a young plant root where new cells are being feverishly created to grow the root. Indeed, I've tried looking for it myself a few times. I've yet to succeed in getting any really good results, but rest assured when I do there'll be a posting...<br /><br />I can't resist a small digression at this point to mention <span style="font-style: italic;">microtubules</span>. When it comes to pulling chromosomes apart (i.e. during <span style="font-style: italic;">anaphase</span>), cells do this by strapping tiny cables (<span style="font-style: italic;">microtubules</span>) to chromosomes in a process akin to hauling logs out a log pile by pulling on ropes. These <span style="font-style: italic;">microtubules </span>are <span>tiny </span>(around 25nm across where a 'nm' is a millionanth of a millimetre) and hollow. So tiny are they that some physicists (notably the famous blackhole physicist Roger Penrose) have even speculated that inside microtubules, reality ought to be dominated by the small and weird world of quantum physics (cats being both alive-and-dead; particles being in two places at once - that sort of thing) and that signals propagating inside microtubules in the brain might have something to do with the mystery of human consciousness (you can listen to Penrose give a lecture on it <a href="http://online.kitp.ucsb.edu/plecture/penrose/">here</a>). Anyway, this is a highly contentious claim and a long way from today's discussion. To return to more certain issues:<br /><br />In their paper above Oud et.al. set out to study the <span style="font-style: italic;">three-dimensional</span> arrangement of chromosomes inside replicating cells during <span style="font-style: italic;">prophase</span>. It turns out if you want to study chromosome arrangements inside a cell without being mired in complexity, you can do worse than make use of Smooth Hawks-beard since it has a mere 6 chromosomes (strictly one should write '2n=6' - see my previous explanation <a href="http://lifeonanoxfordlawn.blogspot.com/2010/03/ladys-smock-cardamine-pratensis.html">here</a>). Compare that with humans with (2n=) 46, or some ferns with around a thousand! (I have no idea why there is such variation in nature. Generally, there is no relationship between the number of chromosomes and the complexity of an organism. Anyone?).<br /><br />Trying to image the three-dimensional arrangement of tiny objects is not simple when you remember that looking down a conventional microscope all you see is a flat, <span style="font-style: italic;">two</span>-dimensional view of an object. To achieve a 3D visualisation of chromosomes Oud et.al. used a special type of microscope known as a<span style="font-style: italic;"> confocal scanning laser microscope</span>. As anyone who has a normal microscope knows, images suffer from a limited 'depth of field': only a portion of your object appears in focus. Other parts of an object, at different depths, appear blurred. Often this is a nuisance, but confocal microscopes cleverly use it to advantage. They physically <span style="font-style: italic;">block out</span> light from anywhere other than the one extremely thin section of a sample that happens to be in focus. The advantage of this may not be immediately clear, but the point is that by slowly varying the point of focus, one can build up a stack of images where each image contains <span style="font-style: italic;">only </span>light coming from that single, selected slice through the sample. By taking a bunch of such images from different depths, and stacking them all together (using a computer) one arrives at a three dimensional image.<br /><br />Using this method Oud et.al. arrived at the wonderful picture of the three dimensional arrangement of chromosomes in a Smooth Hawks-beard root cell in their <a href="http://jcs.biologists.org/cgi/reprint/92/3/329.pdf">paper</a>. Of course, their study was not about making 'pretty pictures'. They were interested in adding to biologists' long-standing interest in knowing how chromosomes are arranged in space inside the nuclei of cells; In particular whether the arrangement is random or not. Their conclusion (as I understand it) was that although a range of differing arrangements were observed across cells, overall the chromosomes seemed to arrange themselves in space in a finite number of non-random ways.<br /><br />So there we have it! A week ago, for me, an unknown weed. Now, a named plant with a intriguing inner life. Bye for now.<br /><br />Footnote:<br />I have begun to think that my habit of normally giving only a link to articles isn't the best, as articles may disappear online in future. From now on therefore, I'm going to make an effort to selectively include proper references at the end of postings. To that end:<br />[1] <span style="font-style: italic;" class="citation" id="__citationid1674196">Oud JL, Mans A, Brakenhoff GJ, van Der Voort HT, van Spronsen EA, Nanninga N. Three-dimensional chromosome arrangement of Crepis capillaris in mitotic prophase and anaphase as studied by confocal scanning laser microscopy. <span><span class="ref-journal">J Cell Sci. </span>1989 Mar;<span class="ref-vol">92</span>:329–339</span></span>Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com0tag:blogger.com,1999:blog-2834972773043127807.post-24576525216435466462010-10-10T12:43:00.069+01:002010-10-12T19:12:01.921+01:00A Rotifer, Genus MniobiaI am an amateur naturalist trying to discover everything living in my garden.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6xRM0HLE75O6-sDvnCBmOjBxD013gPhhFXUy9s-jALiIu-6bNE4YiWNkYGWdsmQmazU9cisfB7xzp7tXT9MQNcz05e4nOiQ4NNmeZcw_WFKrb4gpaVFbySYLL6w0d2Smqh009JVOc-59X/s1600/pond+life+tank.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 200px; height: 134px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6xRM0HLE75O6-sDvnCBmOjBxD013gPhhFXUy9s-jALiIu-6bNE4YiWNkYGWdsmQmazU9cisfB7xzp7tXT9MQNcz05e4nOiQ4NNmeZcw_WFKrb4gpaVFbySYLL6w0d2Smqh009JVOc-59X/s200/pond+life+tank.jpg" alt="" id="BLOGGER_PHOTO_ID_5526384742802261010" border="0" /></a>Autumn has arrived in the UK. The leaves are dropping from the trees and the wet weather has created puddles of rain water and detritus in my garden. Hoping to investigate the life therein, and having a cheap plastic fish tank to hand, rather than stand outside getting wet I decided to bring a puddle inside. It makes rather an attractive room feature don't you think?! (Photo 1).<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEigKinzO4nioarq4UnPrBxL4x1WDLVQyHGz2ABzdZWEfzGHl9AWT4PQkhO8VdoAmVRF7NAAN4o4V7apQH36wxwcOejl1cBuT40buyUA2oRizXQO47NrFszbDWibr4JqjV7rvW2DxgVTLPCH/s1600/Rotifer+Mniobia.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 400px; height: 300px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEigKinzO4nioarq4UnPrBxL4x1WDLVQyHGz2ABzdZWEfzGHl9AWT4PQkhO8VdoAmVRF7NAAN4o4V7apQH36wxwcOejl1cBuT40buyUA2oRizXQO47NrFszbDWibr4JqjV7rvW2DxgVTLPCH/s400/Rotifer+Mniobia.jpg" alt="" id="BLOGGER_PHOTO_ID_5526455023628320066" border="0" /></a>Photo 1 shows one of the inhabitants: a rotifer.<br /><br />Rotifers have long been a favorite of amateur naturalists. Under the microscope they have instant appeal. Take a drop of pondwater and you'll find smaller creatures swimming around (algae, protozoa, fungal spores...) but all tend towards the 'minimalist', typically a single, roughly spherical cell. Rotifers by comparison have a true multicellular body. The amateur gets to search for eye spots, 'buccal tubes', kidneys, ovaries... add to this the wonderful, whirling 'wheel organs' at the front of the head, setting up eddies in the water and dragging hapless prey into the mouth and onwards to the tiny but perpetually snapping jaws ('trophi'), and you have a recipe for many hours of fascinating microscope viewing. In photo 1 I didn't manage to capture the 'wheel organs'. There are some virtuosic photos by Charles Krebs <a href="http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artoct08/wd-rotifer2a.html">here</a>. Ultimately however there's no beating moving images, <a href="http://www.youtube.com/watch?v=YF8OJt_pujc">these</a> being a fine example.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg23lItL_LKhYjB05d6e0ae4XDF_6hyphenhyphenTBiexBiUs9xEqNpoYI442FtKPzPGsqtLuHQoGxpDISHdF3eW_h_vej_V-attmOA5OApZl5sqT9dD7JTCaycW8k97ITU4HAI9XPDCccsfGHfUenZf/s1600/Rotifer+Mniobia+foot.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 320px; height: 180px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg23lItL_LKhYjB05d6e0ae4XDF_6hyphenhyphenTBiexBiUs9xEqNpoYI442FtKPzPGsqtLuHQoGxpDISHdF3eW_h_vej_V-attmOA5OApZl5sqT9dD7JTCaycW8k97ITU4HAI9XPDCccsfGHfUenZf/s320/Rotifer+Mniobia+foot.jpg" alt="" id="BLOGGER_PHOTO_ID_5526899047150256530" border="0" /></a>When it comes to identifying my rotifer I don't have any dedicated books. I did find a basic key in my copy of <span style="font-style: italic;">Microscopic Life in Sphagnum</span> (<span style="font-style: italic;">Marjorie Hingley, Richmond Publishing) </span><span>however</span>. Some of the features of importance for rotifer identification include the presence of any hard shell ('lorica') and the presence of any eye spots. Mine has neither. The foot is another important feature. My rotifer crawled around 'inch worm' fashion beneath a microscope cover slip and obligingly gave me the views in photo 2. The labelled features point to my rotifer being in the genus <span style="font-style: italic;">Mniobia</span>. As always, I'm happy to have any reader correct me.<br /><br />The professionals too have given their attention to rotifers. One feature that has provoked serious study has been rotifer sexual reproduction. For many rotifer species, males are very rare. For some, no male has ever been found. How and why rotifers accomplish this, when almost everywhere else in the animal kingdom evolution has rendered reproduction reliant on two sexes, has been actively researched. I considered making this the topic for today's posting. I decided instead however to talk about some experiments into rotifer populations by a Professor Gregor Fussman and colleagues (very helpfully Prof. Fussman has made his all papers available online <a href="http://biology.mcgill.ca/faculty/fussmann/publications.html">here</a>).<br /><br />Biologists have long been interested in trying to model the dynamics of populations. Suppose an isolated island starts out supporting a population of, say, a hundred rabbits and ten foxes. Biologists would like to be able to predict how many foxes might exist on the island a certain number of years into the future. The non-mathematically-minded amongst you (the others might want to skip this bit) might be puzzled by the meaning of the word "model" in the sentence before. Basically it means this: Take a pen and paper. In the middle of your page write an equals sign ('='). On one side of the equals-sign write a letter ('f' say) to represent the thing you're trying the predict (here, the rate at which the fox population is changing). On the other, write all the stuff you guess 'f' depends on - for instance, one might guess the size of the fox population would depend on the size of the rabbit population, the breeding rate of foxes, the old-age-limit of foxes etc. Finally, take the equation you've by now written down, and stuff it into a computer (i.e. tell the computer to plot a graph of the fox population over time using your equation). Of course there are many subtleties and details in order to do this sort of thing well, but in principal at least that is how population models are done.<br /><br />Rather than 'foxes', Fussman and colleagues set out to model a population of rotifers (<span style="font-style: italic;">Brachionus calyciflorus</span>). The rotifers were feeding on algae ('the rabbits') called <span style="font-style: italic;">Chlorella vulgaris</span> not unlike the alga I blogged <a href="http://lifeonanoxfordlawn.blogspot.com/2009/02/haematoccus-algae.html">here</a>. Rather than an 'isolated island', the environment was a 'chemostat' which is basically a fancy fishtank with tubes in and out in order to controllably input and extract nutrients for the algae to feed on ('grass for the rabbits'). Fussan and team wrote down a set of equations they presumed took account of all the factors that would influence the population growth of their rotifers and fed their euqation into a computer. When the computer results were compared with real life however, they got a surprise: The predictions of their model were in gross disagreement with experiment.<br /><br />In a textbook example of the scientific method the investigators set out to track down the 'missing ingredient' from their equations. The answer, when it was found, was sufficiently surprising and profound to ensure its <a href="http://biology.mcgill.ca/faculty/fussmann/articles/Yoshida_03Nature.pdf">publication in</a> the prestigious journal 'Nature'.<br /><br />The hidden factor influencing their population experiments could be summed up in a word: Evolution. This was a great surprise. After all, the effects of evolution are only 'supposed' to show themselves only over millenia. Evolution doesn't go around dominating the behaviour of fishtanks over a period of a fortnight, right!? What was going on? The answer was subtle: It turned out that the algae in the chemostat occurred in two subtly different forms - the species existed as two clones (I'll call them 'A' and 'B' here). Although only a little different, it transpired that rotifers were unable to 'go forth and multiply' when feeding on one of the clones, 'A', but could happily do so when feeding on the other ('B'). When a population of predatory rotifers was introduced to a population of algae, at first there would be plenty of both types of clone. The hungry rotifers would start to feed on the B's and the rotifer population would grow. Simulataneously, the population of 'A' algae would also grow as they carried on reproducing, free from predation. By contrast, alga B's population would fall, not only because they were being eaten up by rotifers, but also because the bugeoning population of 'inedible' A's was using up an inreasing amount of the tank's nutriants. Eventually the population of 'B' could crash to zero...<br /><br />...And there it was: Darwin's famous "survival of the fittest" acting on a small difference between two sub-species so as to drive one to extinction in mere weeks!<br /><br />Actually, my explanation above is oversimplified. In fact the B's didn't always disappear. Sometimes, it was the rotifers whose population would crash as they ran short of food as the B-algae became scarce. The disappearance of predators would then give the 'B' algae the chance to recover. Rather than complete extinctions, the experimenters often observed more complicated oscillations in population sizes in their tank therefore. Nevertheless, once suitably analysed, the conclusion was the same: Evolution was a powerful force at work in their system.<br /><br />The implications of this discovery for biologists seeking to model important systems may be very large. If evolution is a driving force for the dynamics of algae in a fishtank on short timescales, is it also an important, fast-acting player in such vast and critical eco-systems as the oceans' plankton food chains?<br /><br />I don't know the status of this last suggestion. I do know however that these days a humble puddle in my back garden evokes a new fascination. Hoorah for natural history!Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com2tag:blogger.com,1999:blog-2834972773043127807.post-67051579289530077192010-10-02T13:06:00.058+01:002011-06-07T21:36:16.519+01:00A lichenicolous fungus Illosporiopsis (syn. Hobsonia) christianseniiI am an amateur naturalist trying to learn something about everything living in my garden.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEijJDccstYgyM3Y3lO1Gg7kygg8ADIDQm9g6xVpSoSqgUqC277rQfSxwfHFusP7MmdS5t46AcIa8azMqq1V37dAGk1MrWt0s2mB5S5tEAOONiCFjI5nts8yWrSeQVc5dvmIU6oU1CvgVkT2/s1600/Illosporiopsis+%28syn+Hobsonia%29+christianseneii.jpg"><img alt="" border="0" id="BLOGGER_PHOTO_ID_5526378875883660242" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEijJDccstYgyM3Y3lO1Gg7kygg8ADIDQm9g6xVpSoSqgUqC277rQfSxwfHFusP7MmdS5t46AcIa8azMqq1V37dAGk1MrWt0s2mB5S5tEAOONiCFjI5nts8yWrSeQVc5dvmIU6oU1CvgVkT2/s400/Illosporiopsis+%28syn+Hobsonia%29+christianseneii.jpg" style="cursor: pointer; float: left; height: 267px; margin: 0pt 10px 10px 0pt; width: 400px;" /></a>No, not another lichen posting! Instead, the star of today's posting - the pink blobs in photo 1 - is a fungus. Specifically a <span style="font-style: italic;">lichenicolous </span>fungus (from the Latin <span style="font-style: italic;">colous</span> = <span style="font-style: italic;">living amongst</span> [lichen])<span style="font-style: italic;">.</span><br />
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The lichen being infested here is our <a href="http://lifeonanoxfordlawn.blogspot.com/2008/01/lichen-physcia-tenella.html">old friend</a> <span style="font-style: italic;">Physcia tenella</span>.<br />
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Photo 2 shows the rather lumpy, 'coralloid' texture of the fungal blobs close up.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFvEZ-A7mAIB9IPZbkC8WPgg90eVv6c2iEB0uMpfO5f-AkIUoH9EHLqJoqRYkc1bQLu9Fwk4HP1VfrkeqD43ioxr-HNNy4A9YAKHOQLWdX8tPuL7VkTJ_dsAm_XkPbYmOcGChyphenhyphenvVGqtYyx/s1600/Illosporiopsis+%28syn+Hobsonia%29+christianseneii+2.jpg"><img alt="" border="0" id="BLOGGER_PHOTO_ID_5526379551911023218" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFvEZ-A7mAIB9IPZbkC8WPgg90eVv6c2iEB0uMpfO5f-AkIUoH9EHLqJoqRYkc1bQLu9Fwk4HP1VfrkeqD43ioxr-HNNy4A9YAKHOQLWdX8tPuL7VkTJ_dsAm_XkPbYmOcGChyphenhyphenvVGqtYyx/s320/Illosporiopsis+%28syn+Hobsonia%29+christianseneii+2.jpg" style="cursor: pointer; float: left; height: 214px; margin: 0pt 10px 10px 0pt; width: 320px;" /></a>I first noticed pink blobs of this type some years ago on a country walk. I struggled to identify them for a long time but an acquaintance suggested the fungus <span style="font-style: italic;">Marchandiomyces</span>. Searching the internet for more information led me to the very nice <a href="http://www.lichens.lastdragon.org/lichenicolous/index.html">website</a> of Alan Silverside. There I found pictures of two<span style="font-style: italic;"> </span>species: the rich-pink blobs of <span style="font-style: italic;">M. corallinus</span> and the orangey-pink blobs of <span style="font-style: italic;">M. aurantiacus</span>. I was ready to settle for one of these, but then I noticed a comment alluding to yet another pink-blob species called <span style="font-style: italic;">Illosporiopsis christianesnii</span>. (There is<span style="font-style: italic;"> </span><span style="font-style: italic;">yet</span><span style="font-style: italic;"> </span>another called <span style="font-style: italic;">Hobsonia christiansenii</span> - but as far as I can tell this and <span style="font-style: italic;">Illosporiopsis </span>are the same).<br />
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Distinguishing between these various blobs seemed a forlorn hope. As it said in a paper by Sikaroodi et.al. (<span style="font-style: italic;">Mycological Reserach, April 2001</span>) I came across during my searches<br />
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<span style="font-style: italic;">"These [species] are frequently misidentified because of a paucity of morphological characters"</span><br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEimPnvgRwndFoTbt_CuBQx9OKo6EvDy7NO1j_4HU9o7Ym5i4t64lDHo1qaFCdXXbGgMcwCXQ-htGWrpPuNHaI1ChEEltSQPhzVpEXc-J8fgUfc58v8gjMNh5jfGHwrY85BrpbELctq_GlpJ/s1600/Illosporiopsis+%28syn+Hobsonia%29+christiansenii+conidia.jpg"><img alt="" border="0" id="BLOGGER_PHOTO_ID_5526379956755595010" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEimPnvgRwndFoTbt_CuBQx9OKo6EvDy7NO1j_4HU9o7Ym5i4t64lDHo1qaFCdXXbGgMcwCXQ-htGWrpPuNHaI1ChEEltSQPhzVpEXc-J8fgUfc58v8gjMNh5jfGHwrY85BrpbELctq_GlpJ/s320/Illosporiopsis+%28syn+Hobsonia%29+christiansenii+conidia.jpg" style="cursor: pointer; float: left; height: 240px; margin: 0pt 10px 10px 0pt; width: 320px;" /></a>I was about to quit, but then I caught sight (<a href="http://forum.pilze-bayern.de/index.php?topic=499.0">here</a> and in a <a href="http://www.jstor.org/pss/3807533">paper</a> by Lowen<span style="font-style: italic;"> et.al. Mycologica 78(5), p.842</span>) of a mention that the 'conidia' (= asexual spores) of <span style="font-style: italic;">I. christiansenii</span> had a characteristic 'spiral' appearance. I took a tiny part of my fungus in a drop of water, squashed it between a slide and cover slip and viewed it with my trusty student microscope. The result is shown in photo 3 (click to enlarge).<br />
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I'm not expert enough to be confident of what I'm really looking at here. Furthermore, working at x1000 magnification is a tricky and frustrating business - there's hardly any depth of focus and the slightest knock sends things scudding out of the field of view. Nevertheless I was left pretty confident there were indeed some spiral 'objects' in my sample (the object in the photo inset for example, and another in the main image above the number '3'). On that basis I'm identifying my fungus as <span style="font-style: italic;">Illosporiopsis (syn. Hobsonia) christiansenii</span>.<br />
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Searching more generally for information about lichenicolous fungi I was rewarded by finding the splendid review article by Lawry and Diederich <a href="http://www.lichenology.info/pdf/LawreyDiederich.pdf">here</a>. From this I learn that the whole research topic of lichenicolous fungi is enjoying a purple (pink?!) patch. From a single illustrated species (a gall on the lichen 'Usnea') in 1792, the number of known species grew steadily to reach around 686 in 1989. Over the past 10-years however, as scientists around the world have started look in earnest for such lichen-loving fungi, the number of known species has more than doubled.<br />
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With this explosion in species-count is coming a growing appreciation of just how rich a field-of-enquiry the lichenicolous fungi represent. Take the task of unravelling and understanding the interactions between the attacking fungus and its target lichen. Some fungi are very unfussy, being adaptable to a wide range of lichens. Others have a very intimate and specific relationship with only one or two hosts. Some invaders aggressively attack and kill their target lichen. Others are parasitic, insinuating their hyphae (=the long tube-like cells that make up a fungus) into the cells of their host to suck the juices, vampire-like, from their cells. Some lichenicolous fungi even stage a 'take-over' bid: A lichen is basically a fungus that is 'farming' a crop of algae (see my post <a href="http://lifeonanoxfordlawn.blogspot.com/2007/10/lichen-xanthoria-parietina.html">here</a>). The game plan of some lichenicolous fungi is to kill the 'farmer'-fungus' in order to acquire his algae.<br />
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There are more questions over how lichenicolous propogate and spread themselves. It's hypothesised that some may hitch a lift with roving, lichen-feeding mites. But generally not much seems to be known. There are unanswered questions about the sensitivity of lichenicolous fungi to air quality. Certainly some lichens are incredibly sensitive to impure air, unable to survive even trace amounts of pollution. Whether this holds for their attackers isn't known.<br />
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There are further questions about how lichenicolous fungi affect the ecology of a region. It's been argued by biologists that having a lot of parasites in some eco-system ought to encourage a lot of species diversity. Whether this is born out in regions where parasitic lichenicolous fungi are prevalent however is not well studied however.<br />
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These topics (and a lot more) are discussed in the review above. All in all, I suspect that any amateur naturalist hoping to make some genuine and lasting contribution to scientific understanding could do worse than to cultivate an interest in lichenicolous fungi!<br />
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To return to the pink blob species <span style="font-style: italic;">M. corallinus </span>and <span style="font-style: italic;">I. christiansenii, </span>and the paper I mentioned above by Sikaroodi et.al., a remarkable thing to learn was that these two nominally identical blobby fungi in fact represent two entirely separate fungal kingdoms. There are millions of species of fungi, but (crudely) they can be split into two huge groups. There is a huge group of fungi that grow their spores inside little sausage-shaped bags called asci (see photo 4 on my posting <a href="http://lifeonanoxfordlawn.blogspot.com/2010/02/lichen-aspicilia-contorta.html">here</a>). Such fungi are termed <span style="font-style: italic;">ascomycetes</span>. The other group grow their spores, not inside asci, but on the ends of sausage-shaped protruberences called <span style="font-style: italic;">basdia</span>. Such fungi are termed <span style="font-style: italic;">basidiomycetes</span>. From everything I've read this is a very deep and ancient division, the <span style="font-style: italic;">ascomycota </span>and <span style="font-style: italic;">basidiomycota </span>representing an ancient 'parting on the ways' in the evolution of fungi. What's surprises me therefore, is that whilst <span style="font-style: italic;">M. corallinus </span>and <span style="font-style: italic;">I. christiansenii </span>seem almost indentical in every regard (both are small pink blobs, and both grow on the same types of lichens), whilst the former is a <span style="font-style: italic;">basidiomycete </span>the latter is an <span style="font-style: italic;">ascomycete</span>. Now, sometimes, entirely different lifeforms can end up evolving very similar bodies simply because these are the best bodies for the life they're trying to live ('convergent evolution'): Think 'whales' and 'fishes' or 'birds' and 'bats'. Have two very distant fungal cousins independently evolved the conclusion that if you want to survive on lichen, being a small pink blob is a good way to go? The plot only thickens when you learn that although DNA testing shows the species above to be members of the basidiomycota and ascomycota respectively (and therefore that they should grow their (sexual) spores in quite different ways) in fact for neither species has this (sexual) fruiting stage ever actually been seen! (Though it should be remarked that the same was true of the blob <span style="font-style: italic;">M. aurantiacus</span> until recently when a fruit body ('teleomorph') was discovered by <a href="http://www.lichenology.info/pdf/DiederichSchultheisBlackwellMarchandiobasidiumAurantiacum.pdf">Diederich and co workers</a>).<br />
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So there we have it. A tiny inconspicuous fungus occupying the (to our human eyes) minute and obscure niche of subsisting in the crevices of a lichen. And yet what a rich and unexplored natural history awaits.<br />
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<span style="font-style: italic;">"Great fleas have little fleas upon their backs to bite 'em,</span><br />
<span style="font-style: italic;">And little fleas have lesser fleas, and so </span><i style="font-style: italic;">ad infinitum</i><span style="font-style: italic;">"</span><br />
( Augustus de Morgan, 1806-1871)Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com0tag:blogger.com,1999:blog-2834972773043127807.post-68389317006048611822010-09-30T09:04:00.021+01:002010-10-06T21:40:37.976+01:00Meadow Brown Maniola jurtinaI am an amateur naturalist trying to identify and learn something about, everything living in my garden.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgSROfawsori91mY8XTlLw_VXz07tn5fx9Qd9pWsGFGpcOr11oLoXQmrjKGncFcEnsktwSCXtCQWRSj3zUnsg9FbS77NeKX_oIk6gcKFoeILF07FUJOG45Z1mMPEECLwkhmxJSYMA3hmzRR/s1600/Meadow+brown+Maniola+jurtina.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 400px; height: 300px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgSROfawsori91mY8XTlLw_VXz07tn5fx9Qd9pWsGFGpcOr11oLoXQmrjKGncFcEnsktwSCXtCQWRSj3zUnsg9FbS77NeKX_oIk6gcKFoeILF07FUJOG45Z1mMPEECLwkhmxJSYMA3hmzRR/s400/Meadow+brown+Maniola+jurtina.jpg" alt="" id="BLOGGER_PHOTO_ID_5522617943801192562" border="0" /></a>At the risk of butterfly-blog-overload ("Impossible!" I hear you cry) photo 1 follows on from my last posting and shows a Meadow Brown (<span style="font-style: italic;">Maniola jurtina</span>). The photo was taken late last summer.<br /><br />The Meadow Brown is fairly easy to identify, though it is worth checking you are not looking at a Gatekeeper (see my posting <a href="http://lifeonanoxfordlawn.blogspot.com/2009/08/gatekeeper-pyronia-tithonus.html">here</a>) or Ringlet (some photos <a href="http://www.ukbutterflies.co.uk/species.php?species=hyperantus">here</a>).<br /><br />My specimen here is tattered and faded - not uncommon for the Meadow Brown in late summer. Earlier in the season the upper parts of the wings would have been warm orange.<br /><br />As with my Red Admiral <a href="http://lifeonanoxfordlawn.blogspot.com/2010/09/red-admiral-butterfly-vanessa-atalanta.html">last time</a>, most of what I've learnt about my butterfly is taken from the splendid new book <span style="font-style: italic;">The Butterflies of Britain and Ireland (Jeremy Thomas and Richard Lewington, British Wildlife Publishing). </span>Unlike many guidebooks, which merely supply you the name and a few scant details (foodstuff etc.) for your specimen, this book sets out to survey the literature and provide a scholarly essay on the natural history of each butterfly individually (not unlike what I aspire to do on my blog, though I don't for a moment pretend to the same levels of completeness or professionalism).<br /><br />The Meadow Brown turns out to have a particularly rich history of scientific study. In particular it was extensively studied in the 1950's by the famous lepidopterist E.B. Ford and co-workers who were attempting to bring a new, quantitative understanding to genetics and evolution. Butterflies and moths make very good subjects if you want to study evolution: Their lives are relatively short thereby permitting one to follow some feature of interest across multiple generations. And at the same time, variations in their colourful wing patterns give you a very obvious and visible 'signature' that you can set about trying to relate to their genetic makeup.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjm3OzN50pyoAF8sKgFvpsRGpk_IZMmtvEcOV5kE0xnOT7tVuY0l89GHZJJcx_cwKvPcCZdEAWNaSoxT6fWO2ZmpU3szxT_xXWqEYK3iHpzWO3c4tW2y-mfhbM5Rp-wBIv9KrcIrh2SCzbX/s1600/Meadow+brown+Maniola+jurtina+2.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 320px; height: 240px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjm3OzN50pyoAF8sKgFvpsRGpk_IZMmtvEcOV5kE0xnOT7tVuY0l89GHZJJcx_cwKvPcCZdEAWNaSoxT6fWO2ZmpU3szxT_xXWqEYK3iHpzWO3c4tW2y-mfhbM5Rp-wBIv9KrcIrh2SCzbX/s320/Meadow+brown+Maniola+jurtina+2.jpg" alt="" id="BLOGGER_PHOTO_ID_5522631591126910530" border="0" /></a>Ford and others were interested in a wide variation that occurs in the number and spacing of some black spots that appear on the underwings of Meadow Browns. Unfortunately my Meadow Brown wouldn't stay still long enough for me to get a non-blurred photo of these but you can just about make out some spots towards the bottom of the wings in photo 2 (click to enlarge).<br /><br />At this point I can't resist a small digression to talk about about E.B. Ford. A professor at Oxford University, by many accounts Ford seems to have been a somewhat 'difficult' character. He seems to have been not at all fond of women. He campaigned strongly against their being accepted to the then, all-male, college of All Souls. I also recall hearing somewhere he once refused to give a lecture on the basis that only females had turned up and that therefore there was no one 'worthy' to receive it! (I should add that I have failed to find a reference on the web to back-up this second story. I hope I am not falsely maligning Prof. Ford by it. If someone tells me it's incorrect I'll certainly take it down).<br /><br />I have not found any free online archive of Ford's papers (anyone?). Whilst searching however, I did find an excellent and comprehensive archive of the papers of Ford's long-time co-worker R.A. Fisher <a href="http://digital.library.adelaide.edu.au/coll/special//fisher/index.html">here</a>. (The good people of the University of Adelaide seem to be suffering from the strange delusion - shared by too few UK universities and institutions- that having presumably paid for some piece of university research in the first place, tax payers should get the chance to read the results without having to pay a second time to some private journal publishing house for the privilege!)<br /><br />Anyway, getting back to the Meadow Brown. Through their work, Ford and others discovered some intriguing and puzzling trends in the wing-spot variation of this insect. They discovered, for example, that the typical spot pattern of Meadow Browns on small islands differed from that on larger islands. The question (unanswered at the time) was why?! What were the evolutionary causes and benefits driving this variation?<br /><br />As the book above explains, answers only really emerged much later. The studies by Paul Brakefield were particularly important (you can find one of his papers <a href="https://openaccess.leidenuniv.nl/bitstream/1887/11033/1/029_001.pdf">here</a>). It has become clear that spot variation is linked to habitat, in particular the extent of the ground-cover available in some region. Butterflies living in an area with lots of ground cover (long grass) can spend a lot of their time hidden away. For these butterflies, lots of spots would be a positive hindrance - if anything likely to 'blow their cover' to predators. Butterflies from areas with lots of long grass tend to lack lots of small spots therefore. They retain the big 'eye spots' seen in photos 1 and 2, but when resting in deep grass keep these hidden away behind their lower wings, bringing them out only as a 'startle measure' to frighten predators if they are attacked (I spoke more about eyespots <a href="http://lifeonanoxfordlawn.blogspot.com/2009/08/gatekeeper-pyronia-tithonus.html">here</a>).<br /><br />On the other hand, butterflies living in areas of sparse, grazed, or stunted vegetation (a small, wind-swept island as in Ford and others' study above for example) are forced to spend much of their time 'out in the open'. Such butterflies tend to have a lot of small wing spots. The reason is that these act as an 'always on' predator defence; An attacking bird is drawn to peck at the black spots on the 'expendable' wing tips, reducing the chance that the insect's precious head or body will suffer the first attack and thereby giving the butterfly the chance to escape attack with only minor damage.<br /><br />There is much more than could said, especially about some further differences between male and female Meadow Browns. The former need to spend more time 'on the wing' and hence benefiting from some further differences in spot pattern. Since the authors above have already done it so much better than I might howver, I'll stop here, refer you to their book, and, apropos of nothing, end with a quote from the great P.G. Wodehouse:<br /><br /><span><span style="font-style: italic;">The least thing upset him on the links. He missed short putts because of the uproar of butterflies in the adjoining meadows. </span></span>Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com1tag:blogger.com,1999:blog-2834972773043127807.post-9521621871883917442010-09-25T17:53:00.019+01:002010-09-25T20:04:45.923+01:00Red Admiral Butterfly Vanessa atalantaI am an amateur naturalist trying to learn something about everything living in my garden.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1bFikRhIbuBrvm8nvMcMnYvvw8YV3819Csa_FhgT9e0pKkQk6_fk5GyrLXRiPf_s1B9jq0bXs30YcA8xi-DuJec1y34RHOxTdSacON-2zXD_RLsxUY0FIrk8YQNdIXAn-1AwaPV_z6kLi/s1600/red+admiral+Vanessa+atalanta.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 400px; height: 300px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1bFikRhIbuBrvm8nvMcMnYvvw8YV3819Csa_FhgT9e0pKkQk6_fk5GyrLXRiPf_s1B9jq0bXs30YcA8xi-DuJec1y34RHOxTdSacON-2zXD_RLsxUY0FIrk8YQNdIXAn-1AwaPV_z6kLi/s400/red+admiral+Vanessa+atalanta.jpg" alt="" id="BLOGGER_PHOTO_ID_5520895984644403826" border="0" /></a>Taken last summer, photo 1 shows a butterfly basking in the sun on my garden table. There's no mistaking it as a Red Admiral (Vanessa atalanta).<br /><br />What I have learnt about Red Admirals I have got from reading my newly acquired copy of <span style="font-style: italic;">The Butterflies of Britain and Ireland (Thomas and Lewington, publ. British Wildlife Publishing)</span>. This is a major new work that I can't recommend too highly for the interested amateur. All 72 'properly recognised' species of UK butterfly, each copiously and beautifully illustrated as egg, adult, caterpillar and chrysalis, and each with a full and scholarly essay on its natural history.<br /><br />In common with the Painted Lady I blogged <a href="http://lifeonanoxfordlawn.blogspot.com/2010/03/painted-lady-butterfly-vanessa-cynthia.html">here</a>, the Red Admiral undergoes a remarkable migration. Red Admirals overwinter in Southern Europe, not as adults, but as caterpillars, maturing slowly in the cool Southern winters. In early spring the (by then) adult Admirals start to fly North. Some will fly as far as Scandinavia.<br /><br />When they arrive at a suitably Northern destination, the males set up territories on high ground where they mate with females which go on to lay their eggs, singly, on plants such as nettle (see my posting <a href="http://lifeonanoxfordlawn.blogspot.com/2007/11/stinging-nettle-urtica-dioica.html">here</a>). Eggs hatch after about a week and the emerged caterpillers mature over about a four week period. The caterpillars carry a dozen or so sets of bristles along their bodies and come in two forms: black and green. They have the evolved the remarkable trick of constructing a 'tent' of leaves, sewn together with silk (there's a picture <a href="http://www.butterfly-guide.co.uk/species/nymphalids/uk12.htm">here</a>). Sitting inside they can munch away out the sight of predators. The caterpillars pupate in an attractive grey and yellow-spotted chrysalis to emerge to later as the beautiful butterfly of photo 1. Around October, as the weather cools, these adults fly to back to Southern Europe and the cycle begins again.<br /><br />The book above mentions a fascinating puzzle for a population of Scandinavian Red Admirals. Leaving Scandinavia at the end of summer the adults start out by flying due South. After a time however, they reach the coast in Southern Sweden. At this point the butterflies 'cleverly' turn West in order to minimise the distance they need to fly across open sea before reaching land again at Denmark. From Sweden, the coast of Denmark is 24km away and only barely visible to human eyes in a fine day. How the butterflies are able to detect it and know to turn West therefore is a puzzle. It is speculated that they may be making use of an ability of many insects have to see the 'polarisation state' of light. 'Polarisation' is a property of beams of light that humans can't see, but suffice to say land and water can affect it in different ways. It is theorised the migrating Scandinavian Red Admirals are using this to aid them in detecting land at a distance. This appears to be unproven however. Another of nature's mysteries!Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com5tag:blogger.com,1999:blog-2834972773043127807.post-86401141581045994572010-09-17T20:24:00.073+01:002010-09-30T09:02:20.007+01:00A lichen: Lecidella elaeochromaI am an amateur naturalist trying to discover everything that lives in my garden.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgU5FEM6aP0zjSK0dAtVLrlR2lC6Eo4CWCQaNOMMTA4eBWKsE-ZH3EFN4UJlaYjQNGVt0sWcRrVpfeu9NRWUKnP5lbRuS6z4kkiz2ji4EwQRsTtiXCAJAnf8df_8HgzZJsJRrb6CJMGFh5I/s1600/Lecidella+elaeochroma.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 400px; height: 267px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgU5FEM6aP0zjSK0dAtVLrlR2lC6Eo4CWCQaNOMMTA4eBWKsE-ZH3EFN4UJlaYjQNGVt0sWcRrVpfeu9NRWUKnP5lbRuS6z4kkiz2ji4EwQRsTtiXCAJAnf8df_8HgzZJsJRrb6CJMGFh5I/s400/Lecidella+elaeochroma.jpg" alt="" id="BLOGGER_PHOTO_ID_5518635369324965778" border="0" /></a>Once upon a time there was a large, upright apple tree in my garden. And then quite suddenly, one night, there wasn't!<br /><br />What happened is a story most relevant for this blog...but one for another time. For today let me remark only that this calamity gave me an unprecedented opportunity to inspect my tree's upper branches for one of my favourite lifeforms - the lichens.<br /><br />Photo 1 shows a lichen new for this blog (the grey smudge that is, the yellow is Xanthoria parientina I've blogged <a href="http://lifeonanoxfordlawn.blogspot.com/2007/10/lichen-xanthoria-parietina.html">previously</a>). Photo 2 shows a closeup of my lichen's <span style="font-style: italic;">areolate thallus </span>(=cracked surface) and <span style="font-style: italic;">black, </span><span style="font-style: italic;">lecideine apothecia</span> (= fruit bodies - see my artwork and explanation <a href="http://lifeonanoxfordlawn.blogspot.com/2010/02/lichen-aspicilia-contorta.html">here</a>).<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6yBnC7Qkmt8_g-c8bmob0op94qpGgprn8_NfsKFEYD4AIIxD9IXdeM5XBtZ7PREKLBR09SX_HrEK4FSUI0JQqytVVvL66gZSVDWdzr57jz-hIeUfbfY4VtYCC6ySJQy70VHPR1NgmOoqI/s1600/Lecidella+elaeochroma+close+up.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 200px; height: 150px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6yBnC7Qkmt8_g-c8bmob0op94qpGgprn8_NfsKFEYD4AIIxD9IXdeM5XBtZ7PREKLBR09SX_HrEK4FSUI0JQqytVVvL66gZSVDWdzr57jz-hIeUfbfY4VtYCC6ySJQy70VHPR1NgmOoqI/s200/Lecidella+elaeochroma+close+up.jpg" alt="" id="BLOGGER_PHOTO_ID_5518635850822799730" border="0" /></a>Despite my fondness for lichens I am very far from being an expert. One problem facing the amateur is that many species look rather similar to the eye. Some are all but impossible to separate by anyone who does not happen to possess a forensic chemistry laboratory. (This is not a joke. It is not uncommon for the professionals to turn to e.g. chemical chromatography in pursuit of accurate identifications of lichens).<br /><br />Fortunately there are a few 'tricks' available to the amateur. One is to observe your lichen under UV light. This is not as difficult as it sounds. In my case a battery-powered banknote reader from a 'pound store' (that's 'dollar shop', '100yen shop'... to those of you reading overseas) yielded the rather lovely result at the bottom of photo 2. The point is that had my lichen been the superficially similar <span style="font-style: italic;">Fuscidea cyathoides</span> (picture available <a href="http://www.britishlichens.co.uk/species/Fuscidea%20cyathoides%203%20small.jpg">here</a>), also occasionally found on wood, then UV light wouldn't produce the glow seen here. In the jargon, <span style="font-style: italic;">F. cyathoides</span> is 'UV-' . By comparison, as I learnt from to my copy of Lichens (Dobson, Richmond Publ.) the common UK lichen <span style="font-style: italic;">Lecidella elaeochroma</span> is 'UV+ orange' - clearly a good fit and my identification for today (as always I'm happy to be corrected).<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjxAMACaFC4dH2nMscStJAoloWSNujk9Xf5-f4AGKdUdQu-uPel_SIgsr3Fe9wQpkeH5PvaPoWxBuFB4IZiUs2o5ZwfKbNdun_JnKcdUEj_oRoFQ0E1NXXRyiOLSB3UtkDtpO3Nl5chleU4/s1600/Lecidella+elaeochroma+UV+light.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 261px; height: 320px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjxAMACaFC4dH2nMscStJAoloWSNujk9Xf5-f4AGKdUdQu-uPel_SIgsr3Fe9wQpkeH5PvaPoWxBuFB4IZiUs2o5ZwfKbNdun_JnKcdUEj_oRoFQ0E1NXXRyiOLSB3UtkDtpO3Nl5chleU4/s320/Lecidella+elaeochroma+UV+light.jpg" alt="" id="BLOGGER_PHOTO_ID_5518636118158733122" border="0" /></a>I have mentioned previously a question that I have puzzled over regarding lichen: My (decidedly amateur) understanding of evolution has always been that, over time, it drives species towards adopting the optimal form for surviving in their environment. What has puzzled me is how then, it can be commonplace to see lichens with really quite dissimilar features occupying the same environmental niche. Inspect a few twigs on a tree and it's really not uncommon to find, side-by-side, both <span style="font-style: italic;">crustose </span>(pancake-like) lichens, and, as here say, the bright yellow, <span style="font-style: italic;">foliose </span>(=leafy) lichen <span style="font-style: italic;">X. parientina</span>. To survive on wood, how can it be 'evolutionarily optimal' to be a bunch of bright yellow flakes, <span style="font-style: italic;">and</span> optimal to be a grey pancake. Surely one ought to have 'won the argument'? It was satisfying recently therefore to come across a section in the book <span style="font-style: italic;">Introduction to Bryophytes (Vanderpooten and Goffinet, publ. Cambridge)</span> that I think has given me the inkling of a solution to my confusion.<br /><br />The book describes how some species of moss have become expert in seizing the opportuntity to colonise fleeting, virgin, environments. A newly appeared patch of burnt ground after a forest fire for example. Clearly being 'first moss on the scene' has the benefit you will enjoy the resources of your new home free from the pressure of competition. There is a price to pay for such a lifestyle however. To succeed at rapidly detecting newly emerged environments requires that you to put a great deal of your energies into sending out countless 'scouts' (a.k.a. spores) to explore your environs. By definition, if you're putting your energies into volume spore production, you are precisely <span style="font-style: italic;">not </span>putting them into your own growth (producing lots of leaves etc.). Such 'fugitive mosses' therefore tend to be slight, quick-to-mature, normally annual plants, producing large numbers of small 20um spores.<br /><br />Now 'fugitive' is not the only survival strategy amongst mosses. Enter the dominants. Dominants aim to out-compete other mosses for light and nutriants by growing faster and larger. This is a perfectly reasonable strategy, but again has its limitations. By investing a large proportion of their energy into the rapid growth of leaves etc. such mosses are left with little energy for the production of spores. Dominants then, will be less successful at rapidily discovering new areas, and tend to be larger, perennenial mosses with fewer spores. This is far from the complete story. As well as doimants and fugitives, the book above goes on to discuss the strategy of 'colonists', 'perennial stayers' and 'annual shuttles'. I have not found any freely available articles discussing similar issues for lichen (anyone?), but I think its not unreasoanble to suppose some similar ecology might hold for these fellow tree- and rock-dwellers.<br /><br />All of which brings me back to my puzzle of how evolution can have a arrived at two such different forms (body shapes and colours) as optimal solutions for lichens living in the same place (a twig). I don't pretend a complete answer, but I feel I may have started to get an inkling of understanding. I think my confusion likely stems from woolly thinking on my part, namley, in erroniously imagining that evolution is about optimising a creature's <span style="font-style: italic;">form </span>to fit a <span style="font-style: italic;">place</span>. The more I've thought about the moss examples above however, the clearer it seems to me now that it is not 'body shape' that evolution is working to optimise, but rather the whole organism. That is, not merely its shape and colour, but rather the totality of its life cycle and survival strategy. Furthermore it is not sufficient to think of a lichen's 'environment' as being merely some unchanging point in space (the surface of a twig, say). This misses the very significant additional fact that our twig is subject to an annual cycle of dramatically changing seasons and that it itself is a growing, changing, transitory thing. At the risk of sounding too poetical, thinking of the lichens on my tree now I begin to get an image of a complex spaghetti of life histories and strategies at work. It is facile to try to ask whether 'yellow and flaky' is a 'better or worse' body shape for living on twigs than 'flat and grey'. Instead, each lichen will be following some complex survival strategy with multiple factors and tradeoffs. Viewed in this way, although two lichens have met on a twig in photo 1, viewed over extended time, the 'trajectory' of their lives is no doubt entirely different. The forms they have will be because these are the forms that best befit them to their individual, distinct, extended, life styles.<br /><br />My great pleasure in researching this blog is that through it my view of my garden grows richer all the time. To my mind, no one has said it beter than Martin Luther<br /><span style="font-style: italic;"><br />For in the true nature of things, if we rightly consider, every green tree is far more glorious than if it were made of gold and silver.</span>Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com0tag:blogger.com,1999:blog-2834972773043127807.post-45978688548192469312010-09-11T08:25:00.019+01:002010-09-11T15:04:56.331+01:00An Ichneumon wasp - Amblyteles armatoriusI am an amateur naturalist trying to learn something about everything living in my garden.<br /><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvzVcKzth-3hz-BiGdVOBA2W480cfLuVD0uajVVzzpmWbddax3oUYWEqlV4dGPhxSG7ylPOedLz_pEoC_IZfsvGqsZQmEauWIXvGVyclmi71TlAAuAP_szcMAHhcofaVdF8aNUTq5vZIYl/s1600/Amblyteles+armatorius+ichneumon+wasp.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 400px; height: 267px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvzVcKzth-3hz-BiGdVOBA2W480cfLuVD0uajVVzzpmWbddax3oUYWEqlV4dGPhxSG7ylPOedLz_pEoC_IZfsvGqsZQmEauWIXvGVyclmi71TlAAuAP_szcMAHhcofaVdF8aNUTq5vZIYl/s400/Amblyteles+armatorius+ichneumon+wasp.jpg" alt="" id="BLOGGER_PHOTO_ID_5515554453161220754" border="0" /></a>Hello! After a goodly absence I am back with some more of my garden wildlife. I hope there may be one or two of you out there still reading. Certainly my garden has not run short of new lifeforms to offer. Despite over a 100-species blogged so far, I have a long backlog of additional finds with more turning up all the time.<br /><br />Photo 1 shows a magnificent insect I spotted resting on my hedge in late-summer of last year. The body was around a cm in length. Based on some similar images on the web I'm identifying it as an Ichneumon wasp - <span style="font-style: italic;">Amblyteles armatorius.</span><br /><br /><br />With tens-of-thousands of species of Ichneumon wasp worldwide and about 3200 in Britain alone, definitively identifying Ichneumons is a job for the specialist. Dr Gavin Broad is one such and has helpfully made available an online British <a href="http://www.brc.ac.uk/downloads/Ichneumonidae_checklist.pdf">checklist</a> and <a href="http://www.brc.ac.uk/downloads/Ichneumonidae_subfamily_key.pdf">a key to the sub-families of Ichneumonidae</a>. You can download the entire 380-odd pages of the 1903-published <span style="font-style: italic;">Ichneumonologia Brittanica</span> for free <a href="http://www.archive.org/details/ichneumonologiab03morl">here</a>. For any naturalist willing to grapple with the subject however, a supreme example of what can be achieved (and surely a candidate for "all-time greatest garden study") is given by Jennifer Owen. Her book, <span style="font-style: italic;">The Ecology of a Garden (Cambridge Uni. Press)</span> records 15 years of painstaking cataloguing of the wildlife in a UK garden. During her studies Dr Owen discovered no fewer than 529 species of Ichneumon of which 15 were new to Britain and a staggering 4 were new to science!<br /><br />From the comments above it will be understood my amateur's identification, based on a photograph alone, of my wasp as <span style="font-style: italic;">A. armatorius</span> is to be treated with caution. It is certainly not the only European black -and-yellow striped Ichneumon as can be seen, for example, from the photo's <a href="http://aramel.free.fr/INSECTES14ter-3-1.shtml">here</a> of species such as <span style="font-style: italic;">Ichneumon stramentor, I. xanthorius, Eutanyacra crispatoria</span> and <span style="font-style: italic;">Diphyus quadripunctarius</span>. For now I'm sticking with <span style="font-style: italic;">A. armatorius</span>, as some of these others have yellow-striped antennae and other small differences, but I'm happy to be corrected by any of the experts out there.<br /><br />Sadly, I have been able to uncover rather few details of the natural history of my Ichneumon. I have learnt that it is fairly common in the UK and <span style="font-style: italic;"></span>the <a href="http://www.insectoid.info/wasps/ichneumon-wasps/amblyteles-armatorius/">sole species</a> in the genus <span style="font-style: italic;">Amblyteles</span>. Adults apparently feed on pollen, that of umbellifers being a common target. In common with many other ichneumon's, the larvae are parasites of caterpillars, one target moth being The Yellow Underwing (<span style="font-style: italic;">Noctua pronuba</span>). The larvae hatch inside the caterpillar and devour it from the inside. Other target moth species besides the Yellow Underwing are variously stated for <span style="font-style: italic;">A. armatorius</span>. The scientific paper by Rolf Hinz (Entomofauna, 6(8), 1985, pp.73-77) disputes these claims however.<br /><br />The paper above is in German incidentally, which is unfortunate if like me, you don't speak the language! (I found a free online copy of this paper some time ago, but have entirely failed to relocate it since. Anyone?). Since this was one of the very few learned articles I came across on <span style="font-style: italic;">A. armatorius</span> however, I was determined not to be put off and came up with the idea of running the German text through Google's free, online automatic translation service. The results of computer translation are not always transparent. A German sentence that, in the original, I take to say something along the lines:<br /> <span style="font-style: italic;">"I'm grateful to </span><span style="font-style: italic;" id="result_box" class="long_text"><span title="">Messrs. G. and E. MannBausch Heidt of the </span><span title="">Künanz Upland Bird-research Centre</span></span><span style="font-style: italic;" id="result_box" class="long_text"><span title=""> for supplying me with specimens</span></span><span style="font-style: italic;" id="result_box" class="long_text"><span title="">"</span></span><span id="result_box" class="long_text"><span title=""></span></span> <span id="result_box" class="long_text"><span title=""><br />gets translated as<br /> <span style="font-style: italic;">"Messrs. G. and E. Mann Bausch</span></span><span style="font-style: italic;" title=""> Heidt from the research Künanz bird-house in the mountain, the procurement of the material allowed, thanks.</span></span><span style="font-style: italic;">"<br /></span>Nevertheless, with patience it's generally possible to get the gist and I'll certainly consider using this approach in future.<br /><br />I appear to have digressed! When starting today's posting it had been my intention to say something on the amusing topic of the religious debate sparked amongst Victorians naturalisists by the life-style of the Ichneumonidae. Since I have written enough for now however, and since, with another 3000-odd British Ichneumonidae out there, I feel confident I will have other chances to revisit this fascinating family of insects in the future, I will leave my somewhat cryptic last sentence hanging in the air and bid you farewell for now.Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com3tag:blogger.com,1999:blog-2834972773043127807.post-14624874525955905232010-05-07T21:29:00.043+01:002010-05-08T23:30:18.576+01:00Two Prominent MothsI am an amateur naturalist trying to identify everything living in my garden.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivYKv4C8YyyjNELHR7okTM-wKL6ffnHz7SJ0O8iz7KB3jww4Yxs7_omWaa7Pcpp556BX9EO5Xly3KiQdddGUil-JGAhCM3sKqMXZ9kWLXhehh1fTBmYYN1YOjR6EdlalaW7vhfnZEH2E8S/s1600/moth+trap.jpg"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer; width: 200px; height: 134px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivYKv4C8YyyjNELHR7okTM-wKL6ffnHz7SJ0O8iz7KB3jww4Yxs7_omWaa7Pcpp556BX9EO5Xly3KiQdddGUil-JGAhCM3sKqMXZ9kWLXhehh1fTBmYYN1YOjR6EdlalaW7vhfnZEH2E8S/s200/moth+trap.jpg" alt="" id="BLOGGER_PHOTO_ID_5469017703860060690" border="0" /></a>Some time ago I blogged the moth trap I was constructing. My first design was only partially successful (most of my catch were escaping!) and since then my designs have undergo a number of iterations to finally arrive at <span style="font-style: italic;">The Walloon Super Trap</span> you see before you in photo 1! I'm pleased with this design. In fact, the only problem is that the few times I've put it out in my garden it has yielded such a bumper catch of night-time insects I now have a long backlog awaiting a write up on this blog.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbc3ZHGOd5bk7XwrzMCSaiR9JK-NHGUpIN36uF_igyzUlWOwrmjJl7a6IyEQ4CN6zV4isSBetUipzFOqhE6ussVQfzGhAggzyVLcObybM6DBNchfEt1bLxlL_H2JXNK3Jw9y6_3WPFXccX/s1600/lesser+swallow+prominent+Pheosia+gnoma.jpg"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer; width: 320px; height: 214px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbc3ZHGOd5bk7XwrzMCSaiR9JK-NHGUpIN36uF_igyzUlWOwrmjJl7a6IyEQ4CN6zV4isSBetUipzFOqhE6ussVQfzGhAggzyVLcObybM6DBNchfEt1bLxlL_H2JXNK3Jw9y6_3WPFXccX/s320/lesser+swallow+prominent+Pheosia+gnoma.jpg" alt="" id="BLOGGER_PHOTO_ID_5468633931551156754" border="0" /></a>Anyway, on to the stars of today's posting. Photos 1 and 2 show two moths trapped (for the record) on 25th and 22nd April 2009 respectively (I let them go after I'd taken their photos).<br /><br />A little time spent with my copy of Field Guide to Moths (Waring, Townsend) and I was able to identify the first as a Lesser Swallow Prominent (<span style="font-style: italic;">Pheosia gnoma</span>) and the second as a Coxcomb Prominent (<span style="font-style: italic;">Ptilodon capucina</span>). I'm guessing the various points and fluffy quiffs on my moths are there to resemble thorns and to break up the moths' outline when resting on branches.<br /><br />The Lesser Swallow Prominent is superficially similar in appearance to the Swallow Prominent (<span style="font-style: italic;">Pheosia tremula</span>) but the neat white triangle on the upper part of the wing identifies my moth as the former. The caterpillars feed on Birch and the book tells <a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgPz8UB1ULG_L3UVG3mt2qB0ee2EHPNru5-w_I5sISyplqItR4J0bT3fNMeJMDIxSwGTsrTp70mVTEIxfnUfVM4M-mHPfDTA2eALBwcMF8WOb25pzn2-8ZXrTy-CBPsF_0BxvQym0SEEFc5/s1600/Coxcomb+Prominent+Ptilodon+capucina.jpg"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer; width: 240px; height: 320px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgPz8UB1ULG_L3UVG3mt2qB0ee2EHPNru5-w_I5sISyplqItR4J0bT3fNMeJMDIxSwGTsrTp70mVTEIxfnUfVM4M-mHPfDTA2eALBwcMF8WOb25pzn2-8ZXrTy-CBPsF_0BxvQym0SEEFc5/s320/Coxcomb+Prominent+Ptilodon+capucina.jpg" alt="" id="BLOGGER_PHOTO_ID_5468634103893061106" border="0" /></a>me it is fairly common in the UK.<br /><br />The Coxcomb is also common. Its larvae feed on a variety of trees including birch, hazel and hawthorn.<br /><br />My moths are both members of the <span style="font-style: italic;">Notodontidae </span>family of moths of which 27 species have been recorded in Britain (there are several thousand worldwide). My attempts to learn something of them led me to some fascinating online papers about the sense of hearing in moths.<br /><br />It turns out the <span style="font-style: italic;">Notodontidae </span>moths are notable for having some of the simplest ears of any insect. To we humans, insects wear their ears in rather strange positions - sometimes on the legs, sometimes the thorax and even (in the case of some lacewings) on the wings. <a href="http://www.blogger.com/www.mantislab.com/398.pdf">This</a> paper by Yager gives a review.<br /><br />Insect ears broadly follow a common design. A thin membranous 'ear drum' (the <span style="font-style: italic;">tympanal membrane</span>) vibrates in response to sound and the vibrations are detected by structures called <span style="font-style: italic;">scolopidia </span>that are basically stretch receptors. The scolpidia detect movements of the membrane and fire off signals down a connecting nerve. Some grasshoppers have around 2,000 scolopidia. Notodontid moths are at the other extreme with only one.<br /><br />Yager's paper above quotes the remarkable figure of 1 Angstrom (=a ten-millionth of a millimetre) as the smallest vibration of the membrane that insect ears can detect. If true, I find this truely incredible as 1 Angstrom is about the diameter of a single atom!<br /><br />I did not manage to find any freely available references to the hearing specifically of my moths, but I have come close with <a href="http://www.blogger.com/jeb.biologists.org/cgi/reprint/113/1/323.pdf">a paper by Annemarie Skurlykke</a> on the hearing of the Swallow Prominent (you'll recall my moth above is the <span style="font-style: italic;">Lesser </span>Swallow Prominent). From this I learn that the Swallow Prominent hears best at frequencies around 60kHz. For perspective, the highest note an adult human can hear is said typically to be around 20kHz. Why should moths be sensitive to such high ('ultrasonic') frequencies? The answer can be summed up succinctly: Bats! Bats are prodigious predators of night flying insects and hunt by echolocation using ultrasound.<br /><br />I came across a couple of interesting online review articles (by <a href="http://www.erin.utoronto.ca/%7Ew3full/reprints/2008RatcliffeEtAlMothFlightsCJZ.pdf">Ratcliffe <span style="font-style: italic;">et.al.</span></a> and another by <a href="http://www.life.umd.edu/faculty/wilkinson/honr278c/PDF/Miller01.pdf">Miller and Surlykke</a>) describing how moths and other insects react to hearing an approaching moth. It seems that many moths react in two stages. If the bat is some distance away the moth simply flies away from the sound of the echolocating bat. If the bat gets close enough to strike however, the moth takes more dramatic action such as spiralling in flight or even folding its wings and dropping out of the air. How moths are able to determine the range of the bat isn't fully understood. Bats reduce the time between their ultrasonic squeaks as they get near to striking an insect however in order to better 'see' their prey, and the suggestion is that the moths are sensitive to this increase in squeak-rate. Regardless of how they do it the defence seems fairly successful with those species of moth capable of hearing and reacting to bats improve their survival chances by some 40%.<br /><br />Of course moths do not get everything their own way. Firstly, diving to the ground is fine...unless (as <a href="http://www.erin.utoronto.ca/%7Ew3full/reprints/2004GuignionFullardCJZ.pdf">Guigon and Fullard</a> explain) the 'ground' turns out to be water! Naturally also the bats are not about to take things lying down and have evolved a number of strategies to bypass the moths' defences. Some appear to have adopted frequencies above or below the range of moths' hearing and others may rely to a significant extent on simply seeing (visually) or listening for their prey. Ultimately however, as <a href="http://www.life.umd.edu/faculty/wilkinson/honr278c/PDF/Miller01.pdf">Miller and Surlykke</a> comment "<span style="font-style: italic;">some barbastelle bats prey almost exclusively on tympanate moths, and just how they do this is not known</span>". Another of nature's puzzles!Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com3tag:blogger.com,1999:blog-2834972773043127807.post-64006660492469449962010-04-24T12:48:00.051+01:002010-05-01T22:16:05.223+01:00A signalling fly Poecilobothrus nobilitatusI am an amateur naturalist trying to learn something about everything living in my garden.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdC7ZYOalTT5EJp-A9jcakkBTuXUUHEslUMwzCnsY2KnR57NhIKBQRHaxDlFi7ix5y670IWaCmipEpZphrKHxaV76MwIEHZwftFqcJOj7QV-tckgjtYCvLdKL3xjS5wxgXZTSl5hsRuFX7/s1600/Poecilobothrus+nobilitatus+flies+signalling.jpg"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer; width: 400px; height: 267px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdC7ZYOalTT5EJp-A9jcakkBTuXUUHEslUMwzCnsY2KnR57NhIKBQRHaxDlFi7ix5y670IWaCmipEpZphrKHxaV76MwIEHZwftFqcJOj7QV-tckgjtYCvLdKL3xjS5wxgXZTSl5hsRuFX7/s400/Poecilobothrus+nobilitatus+flies+signalling.jpg" alt="" id="BLOGGER_PHOTO_ID_5463670954521802642" border="0" /></a>I have a plastic tub in my garden that has become partly filled with rainwater. Passing it last summer, my attention was caught by some flies busying themselves at the water's edge. A closer look revealed some fascinating behaviour: the wings of my flies were characteristically marked and the flies were solemnly raising and lowering them just as might an airport worker guiding a plane to a parking spot with a pair of semaphore flags.<br /><br />I took some photo's though I confess I rather expected to fail to identify my fly. There are so many species (<a href="http://www.faunaeur.org/experts.php?group_id=92">more than 15,000 in Europe</a>) that to identify an unknown fly can be a tall order unless you're willing to spend hours with a magnifying glass and have access to some serious, specialist literature. Fortunately however, it turned out my fly is not uncommon, its behaviour having been noted by a fair few people, and an internet search led me to the species name: <span style="font-style: italic;">Poecilobothrus nobilitatus</span>.<br /><br />The stately wing-spreading displays of my fly are part its <span style="font-style: italic;">courtship display</span>. As everyone knows, courtship displays are very widespread in the animal kingdom and can be fantastically intricate (one need only think of peacocks or the dance of Great Crested Grebes (video <a href="http://www.rspb.org.uk/wildlife/birdguide/name/g/greatcrestedgrebe/videos.aspx">here</a>)) . It's very natural to wonder what purpose such displays serve. Vast amounts of literature exist on this topic, with a great many unknowns and disputed theories. I don't have anything like the knowledge to comment expertly. My blog is about my learning something of my garden's natural history however, so a few facts gathered from some general reading on my part seem in order:<br /><br />According to my copy of <span style="font-style: italic;">An Introduction to Behavioural Ecology (Krebs and Davies)</span>, the modern view is that, at the deepest level, courtship arises from a <span>conflict </span><span>between males and females </span><span>over scarce resources</span>. The point is that sperm are small and energetically 'cheap' to produce. Eggs, however, are larger and energetically more costly to produce and gestate. In the jargon<span style="font-style: italic;">, </span>eggs are a <span style="font-style: italic;">scarce </span><span style="font-style: italic;">resource</span>. Since eggs are, in this sense 'expensive, high value objects' it is worth males investing effort and energy competing for them. Equally, for females it pays to be 'choosy' when it comes to 'cashing in' the energy investment an egg represents.<br /><br />The argument above might seem rather abstract, but its consequences are deep. Take the issue of mating with a wrong species: Some species of fruit flies for example, can and sometimes do, interbreed. Often this inter-species breeding results in sterile offspring however. From the perspective above, such parents have wasted precious time and energy. Clearly, it would have benefited them to have had some way to accurately check a prospective partner's species prior to mating. The elaborate courtship dances of some fly species (see <a href="http://www.phschool.com/science/biology_place/labbench/lab11/observe.html">here</a> for example) may be just this: a way for females to check whether a male is of the correct species. From the female viewpoint, this avoids wasted energy on improper fertilization of her 'expensive' eggs. From the male point of view, although dancing costs him some energy, eggs are a scarce resource and having found some (i.e. a fertile female) it is worth the investment.<br /><br />To take a second instance: Since eggs are a scarce resource it is important to lay them somewhere safe and where there is enough food available for the hatchlings. Some courtship displays - such as those where a male presents a female with some 'gift' (say, a morsel of food or a beak-full of nesting material) may be a way for the sexes to share the energetic cost of laying in a particular location (the female pays the cost of depositing her precious eggs; the male pays the cost of finding and presenting a 'courtship gift' that proves the location's suitability).<br /><br />Yet another purpose of a courtship display may for females to test whether a male is a fit, strong individual, and able to pass on good genes to the egg. Actually, one needs to be a little careful before asserting a given courtship display is about a male demonstrating genetic fitness. To see why, imagine a species of bird that shows-off some glossy plumage during courtship. To say the male is demonstrating genetic fitness, makes an <span style="font-style: italic;">assumption </span>that there exists an (inheritable)<span style="font-style: italic;"> </span>gene for glossy plumage for that bird. There may be, but on the other hand there may not. It could be that a male's glossy feathers are nothing to do with his genes but are due to him having been living somewhere that allowed him a good a plentiful food supply. The fact that females are choosing glossy feathers may be nothing (or perhaps only indirectly) to do with a male's genes, but because they say: "<span style="font-style: italic;">Food here is plentiful. It's a good place to breed</span>". The point is not that advertising 'good genes' can never be a reason for a courtship display, simply that one cannot take it for granted as an explanation.<br /><br />Anyway, in summary, a modern view is that courtship is about competition for resources between males and females. The successful male gets the benefit of the female's energy investment in eggs. In return females get an energy expenditure (=courtship display) from a male that relays something of benefit such as '<span style="font-style: italic;">this is a good place to lay</span>', or '<span style="font-style: italic;">the male before you is the correct species</span>', or '<span style="font-style: italic;">the male before you has 'good' genes</span>', or...(there are lots of other scenarios).<br /><br />This barely makes a dent on a vast subject of course, and a great deal more could be written on the theory of courtship. This isn't the place to do it however, and instead let's get back to talking specifically about the my fly <span style="font-style: italic;">P. nobilitatus</span>:<br /><br />The best freely available online paper about my fly I came across was that of <a href="http://beheco.oxfordjournals.org/cgi/reprint/14/4/526.pdf">Zimmer, Diestelhorst and Lunau</a> which describes the courtship behaviours of eight, so-called 'long legged flies' (<span style="font-style: italic;">Dolichopodidae</span>), mine included. A number of these flies carry display 'badges' they use in courtship. <span style="font-style: italic;">Liancalus virens</span> for example, also has signalling spots on its wings (see picture <a href="http://ecocdk.free.fr/Dolicho/Grm/Grm.htm">here</a>). <span style="font-style: italic;">Neurigona quadrifasciata</span> (<a href="http://chwastowisko.wordpress.com/mieszkancy/muchowki/">here</a>) uses foot markings to signal to females.<br /><br />The paper provides a number of interesting facts about my fly. Firstly, experiments show that male wing span is directly proportional to body size: males with a big thorax also have big wing spans. During courtship <span style="font-style: italic;">P. nobilitatus</span> males work to keep at a constant distance of 2.5cm from females. Taking these facts together, a plausible hypothesis is that female <span style="font-style: italic;">P. nobilitatus</span> flies consider male body size important (as an indicator of a male's health status perhaps). By this argument the male's wing badges and constant- separation-dance are present in order to help females accurately estimate the body size of their suitor by sight.<br /><br />Another intriguing suggestion in the paper is that males may have evolved signalling 'badges' to allow them to mate on the ground. The idea is this: some species of flies court in flight with males performing aerial stunts or hovering. Presumably these difficult and energetic winged manoeuvres may again allow females to assess health by looking at, say, wingspan. Now, suppose a male could 'con' a female's reproductive senses into thinking she was being presented with a hovering male when in fact both were sat firmly on the ground?! This is not as implausible as it sounds when we remember we are talking about a little fly whose intelligence and eyesight are not necessarily great! The female's reproductive senses may detect the 'beating' wings of a hovering male simply by whether her eyes detect (say) the outline of a wing and certain patterns of light and dark in the space before her. If a male could replicate these patterns whilst still on the ground, he might be able to fool the female's senses into a mating response, and at the same time save himself from the energetically costly business of hovering. The technical term for such cheating is 'sexual mimicry'. The paper concedes that this idea remains unproven for the long legged flies. I hope you'll agree however it's fascinating stuff and it all goes to show just how incredibly rich and intricate are the patterns of life just outside our front doors.Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com4tag:blogger.com,1999:blog-2834972773043127807.post-46394321315319377652010-03-20T13:29:00.032+00:002010-04-10T17:13:15.700+01:00Lady's Smock Cardamine pratensisI am an amateur naturalist trying to learn something about everything living in my garden.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjjCC4_EB1TjVPUMlJahUT81eZ1-570YyFLZQ3V6HnxozMMv1AW-FO1V4GeHjJKR_dDdZTE1vcKkKHFvjtUGpRa8hIyT9TSzFcYs-BssYBFqszY1yVvZGYEX9U3v6LkGXEjziEJJJyMqBJa/s1600-h/Lady+Smock+Cardamine+pratensis.jpg"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer; width: 300px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjjCC4_EB1TjVPUMlJahUT81eZ1-570YyFLZQ3V6HnxozMMv1AW-FO1V4GeHjJKR_dDdZTE1vcKkKHFvjtUGpRa8hIyT9TSzFcYs-BssYBFqszY1yVvZGYEX9U3v6LkGXEjziEJJJyMqBJa/s400/Lady+Smock+Cardamine+pratensis.jpg" alt="" id="BLOGGER_PHOTO_ID_5450717712219125666" border="0" /></a>Photo 1 shows an attractive flower I found growing wild in a neglected corner of my garden early last summer.<br /><br />A little time spent with my trusty copy of <span style="font-style: italic;">The Wildflower Key (Francis Rose)</span> and I'm fairly confident my plant is <span style="font-style: italic;">Lady's Smock</span>. The leaves of my plant are also rather characteristic (photo 2) with the lower leaves tending towards round with the largest leaf being the one furthest from the stem, whilst the upper leaves are rather long and narrow.<br /><br />My copy of The Englishman's Flora (Geoffrey Grigson) lists around thirty alternative common names for <span style="font-style: italic;">Lady's Smock</span> from the pretty <span style="font-style: italic;">Cuckoo Bread, Cuckoo flower, Lucy Locket</span> and <span style="font-style: italic;">Milking Maids</span> to the less flattering <span style="font-style: italic;">Pig's Eyes</span> and <span style="font-style: italic;">Bog Spink</span>!<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-4DkE8bm9JRx9KArw8Q5K6OVkL3iJfKS3RW8AAzk36z97_-no21yrPU7NAU1hoayJ_I0cPNhlfLOeSmFICsiO3VKMJYwwyhyphenhyphen4YABUglFyuTFIVWoOrrhhAhbxnPVWF-_hHq0KRbsZ5luC/s1600/Cardamine+pratensis+leaves.jpg"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer; width: 213px; height: 320px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-4DkE8bm9JRx9KArw8Q5K6OVkL3iJfKS3RW8AAzk36z97_-no21yrPU7NAU1hoayJ_I0cPNhlfLOeSmFICsiO3VKMJYwwyhyphenhyphen4YABUglFyuTFIVWoOrrhhAhbxnPVWF-_hHq0KRbsZ5luC/s320/Cardamine+pratensis+leaves.jpg" alt="" id="BLOGGER_PHOTO_ID_5458537124248955282" border="0" /></a>The scientific name for my flower is <span style="font-style: italic;">Cardamine pratensis</span>. <span style="font-style: italic;">Pratensis </span>is from the Latin '<span style="font-style: italic;">of meadows</span>'. From some web searching I <a href="http://www.arthurleej.com/p-o-m-Mar07.html">understand</a> <span style="font-style: italic;">Cardamine</span> owes its heritage to the anicent Greek physician Dioscorides (ca. 50AD) who used the name for some cress-like plants<span style="font-style: italic;">,</span> <span style="font-style: italic;">karda</span> being Greek for 'heart', and <span style="font-style: italic;">damao</span> to <span>'tame </span>or<span> overpower</span>'. (I've read that Lady's Smock is an edible, spicy, salad leaf, though I can't vouch for the truth of this.)<br /><br />Lady's Smock is a favoured food of the caterpillars of the Orange Tip butterfly.<br /><br /><span style="font-style: italic;">C. pratensis</span> is a perennial, native to the British Isles and is highly variable. The paper <a href="http://www.blogger.com/ibot.sav.sk/karolx/PDF_files/PSE1996.pdf">here</a> gives a flavour of the lengths the professionals have gone to in attempting to characterise it. My copy of New Flora of the British Isles (Stace) sums things up rather bluntly however as "<span style="font-style: italic;">impossible to subdivide usefully; identity of [named] variants [...] is very dubious"</span>. My attempt to get some basic amateur understanding of the issue led me into a study of <span style="font-style: italic;">polyploidy</span>. I'm certainly no expert on genetics but briefly my understanding is this:<br /><br />As most people know, at times the DNA inside living cells gets packaged into structural units, the <span>chromosomes</span>. A microscope reveals we have 46 chromosomes. Closer investigation reveals that these 46 are in fact present as two largely similar sets of 23 i.e. 23 chromosomes from our mother and a similar 23 from our father. (The phrase 'largely similar' skips over a wealth of detail, such as the fact that a certain chromosome from our mother might carry a different characteristic, say eye colour, to that from our father etc. - but never mind that here) . For humans we say "2n=46". Other mammals have other chromosome counts, for example I read variously on the web that the kangaroo has a mere 2n=12 whilst the European hedgehog boasts 2n=88 (in general there is no link between chromosome number and the size or complexity of a creature).<br /><br />In the case of many plants, a lesser number of insects, amphibians, fish and a very few mammals (one being an Argentinian Plains Rat - see <a href="http://www.polyploidy.org/index.php/Parade_of_Polyploids">the parade of polyploids here</a>!) however, things are more complicated. <a href="http://strawberrygenes.unh.edu/strawinfo.html">Some varieties of strawberry</a> for example contain not, as we humans, <span style="font-style: italic;">two</span> largely similar sets of 23 chromosomes but no fewer than <span style="font-style: italic;">eight </span>sets of seven chromosomes. This gets written as "8x=56". This condition of having more than two sets of chromosomes is termed <span style="font-style: italic;">polyploidy</span>.<br /><br />The fact that more than 30% of plants go in for polyploidy would seem to indicate it must have some important benefits. There are many theories as to what these benfits might be. It's been suggested for example, that polyploidy may promote greater variation in a species and thereby help it evolve ('radiate') more easily into new environments, or that polyploidy may provide protection against 'in-breeding' issues that might otherwise arise for plants that self-fertilise. It seems also that some polyploids are healthier and more vigorous than non-polyploids. In all however, there seems to be no universally accepted theory of why so many plants are polyploids. Another of nature's mysteries!<br /><br />Anyway, all of this preamble basically allows me to comment that my garden weed <a href="http://www.biologie.uni-hamburg.de/b-online/e37/37d.htm">occurs</a> in a bewildering variety of genetic 'forms' from the 'diploid' 2n(=2x)=16 through types with chromosomes numbers of 14, 15, 16, 19, 20, 21 – 28, 30, 32, 37, 42, 44, 45 and 48.<br /><br />After the science, who better to have the last word than the Bard. From the song '<span style="font-style: italic;">Spring</span>' at the end of Love's Labour's Lost:<br /><div style="text-align: center;"><span style="font-style: italic;">When daisies pied and violets blue,</span> <span style="font-style: italic;"><br />And lady-smocks all silver white,</span><br /><span style="font-style: italic;">And cuckoo-buds of yellow hue</span><br /><span style="font-style: italic;">Do paint the meadows with delight,</span><br /></div>Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com3tag:blogger.com,1999:blog-2834972773043127807.post-21559172780626427192010-03-07T10:21:00.040+00:002010-03-13T22:56:52.538+00:00Painted Lady Butterfly Vanessa (Cynthia) carduiI am an amateur naturalist trying to learn something about everything living in my garden.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjz924fmyIQg06WIf_nEQ54US9oXnamieWmbPV0FCTH1TMP_FHc732nGwfOTGB3dCK48Wg6FoX3-8RJFaTR7ltPHbUWR36hp0ruQ065ro_r4PmSLyLKj1MK6nysZZR1wM9fT7b6uQq2_0p5/s1600-h/Vanessa+%28cynthia%29+cardui.jpg"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer; width: 400px; height: 267px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjz924fmyIQg06WIf_nEQ54US9oXnamieWmbPV0FCTH1TMP_FHc732nGwfOTGB3dCK48Wg6FoX3-8RJFaTR7ltPHbUWR36hp0ruQ065ro_r4PmSLyLKj1MK6nysZZR1wM9fT7b6uQq2_0p5/s400/Vanessa+%28cynthia%29+cardui.jpg" alt="" id="BLOGGER_PHOTO_ID_5445835812853568658" border="0" /></a>Photo 1, taken back in late Summer, shows a Painted Lady butterfly enjoying a well-earned rest on a leaf in my garden. I say 'well earned' as this butterfly will likely have undergone an amazing 1000 mile migration, to arrive in my garden from North Africa.<br /><br />The entire British population of Painted Ladies (Ladys?) arrives here in Spring and leaves again in Autumn (strictly not all leave, but those that don't fail to survive the British winter).<br /><br />To have encountered a Painted Lady in my garden last Summer is perhaps unremarkable when you learn that <a href="http://www.butterfly-conservation.org/article/9/100/butterfly_migration_is_biggest_for_years.html">2009 was a mass migration year for Painted Ladies</a> to the UK. Millions arrived, with one flutter (the collective noun for butterflies) alone of 18,000 spotted off the South Coast of England.<br /><br />A fun thing to know (who knows, it may help you win a pub quiz one day!) is that the Painted Lady is the only species of butterfly recorded from Iceland. I got this fact from the admirable <a href="http://www.ukbutterflies.co.uk/species.php?species=cardui">UK Butterflies</a> site, which contains numerous facts and photos about the lifestyle and food preferences of the Painted Lady that I'll not reiterate here. Suffice to say that caterpillars of the Painted Lady are dark and hairy and feed on thistles and nettles.<br /><br />My searches for information on my butterfly were complicated by the fact that some sources seem to use the Latin name <span style="font-style: italic;">Vanessa cardui</span>, others <span style="font-style: italic;">Cynthia cardui</span>, and still others talk about the species <span style="font-style: italic;">cardui</span> in the genus <span style="font-style: italic;">Vanessa</span> and sub-genus <span style="font-style: italic;">Cynthia</span>. I've not had a chance to sort out which is the professionally accepted name. Anyone?<br /><br />Another topic my searches led me to was the (new for me) subject of '<span style="font-style: italic;">foraging theory</span>'. This is a huge topic and the reader should be take my (decidedly amateur) understanding and description with a 'health warning'. Briefly however my understanding goes like this: We've all watched bees and butterflies drifting through patches of flowers, or watched little songbirds working their way through the tree tops pecking at tidbits. Perhaps, like me, you've never really noticed any particular pattern or method to the foraging of these animal. At a glance, butterflies for example, seem to drift along haphazardly, landing on any such plant as they encounter and (one might presume) staying there for as long as it takes to drink a flower's nectar dry. In fact, many years of fabulously detailed studies by armies of biologists have shown that the foraging practices of many animals are anything but random. Quite the contrary, foraging animals have evolved highly specific methods and rhythms, carefully fine tuned to allow them to optimally gather food from their environments.<br /><br />A classic example of decidedly non-random foraging was revealed by the studies by Messrs. Richardson and Verbeek (you can find one of their papers <a href="http://elibrary.unm.edu/sora/Auk/v104n02/p0263-p0269.pdf">here</a>) on the feeding habits of a population of crows in British Columbia. The crows were foraging on a beach for clams. Now, you might naively assume that a crow would simply gobble up any clam it came across. This fails to take account of the fact however, that a crow has first to open up a clam's shell in order to get at the meat inside. Now, little clams don't take much time and energy to open...but then, they don't yield much meat either. Huge clams yield lots meat...but they require the crow to spend a lot of time and energy to get them open. From this you start to realise that if a crow is to get the maximum food benefit from an hour (say) spent feeding, there will be some optimal clam size the crow should target in order to spend the least time for the most meat. Amazingly, this is what the studies showed: the crows were selecting just those sizes of clam that allowed them to maximise their average energy intake.<br /><br />Similar studies have been replicated across many animals with the same results: crabs show optimised strategies similar to those of crows when selecting the size of mussels to open and eat; studies on brooding starlings show that parent starlings will continue to hunt for worms in the field until they are have just the number of worms held in their beaks that optimises the bird's efficiency in getting to and from the nest (Carry too few worms and the parents must make too many energy-sapping flights back and forth to feed the chicks. On the other hand, spending too long in the field trying to peck up worms with a beak already stuffed full is slow and cumbersome and results in the parent trying to carry an excessively heavy load back to the nest); Male Yellow dung flies show behaviour that optimises the balance of time and energy spent feeding vs. the time and energy spent in moving between dung heaps looking for females with which to mate.<br /><br />Actually, although foraging behaviour can be discussed using words as above, in using phrases such as ' <span style="font-style: italic;">the</span> <span style="font-style: italic;">maximum energy acquired per unit time</span>' etc. the numerically minded amongst you may start to realise we are approaching the possibility of a <span>mathematical </span>desciption of foraging ( time-rates-of-change of quantities are the 'bread and butter' of the calculus you may recall from school). A mathematical description of foraging is just what the professional biological community has developed. The classic textbook <a href="http://books.google.co.uk/books?id=w7COsqwlJooC&printsec=frontcover&dq=foraging+theory&cd=1#v=onepage&q=&f=false">Foraging Theory</a> by Stephens and Krebs, gives a flavour.<br /><br />Some of the seminal early work on foraging was by Charnov in 1970's. Charnov developed an important theorem known as the <a href="https://repository.unm.edu/dspace/bitstream/1928/1693/2/TPB76.pdf"><span style="font-style: italic;">marginal value theorem</span></a> which dealt with the situation of an animal foraging between patches of food spaced some distance apart (separated patches of flowers in a meadow for example). The question is, how long should a feeder spend in any given patch before moving on? Spend too long in one patch and the available food dwindles away (the animal is reduced to hunting around for the few remaining 'scraps' so to speak). Equally it takes time and energy to fly between patches. Charnov's theory was developed to predict the optimal time an animal should remain in any one patch in order to maximise its<span style="font-style: italic;"> average <span style="font-style: italic;">rate of energy intake</span></span> (or to put it another way, the foraging pattern resulting in the animal getting, on average, the most calories per hour).<br /><br />All of which preamble, brings me back to the Painted Lady and the papers I came across by <a href="http://jeb.biologists.org/cgi/reprint/156/1/249.pdf">F.R. Hainsworth</a>. Hainsworth studied whether Painted Ladies follow the predictions of <span style="font-style: italic;">the marginal value theorem</span>. Specifically he studied how Painted Ladies reacted to being offered sugar-water solutions of varying strengths. Should Painted Ladies be following the predictions of the marginal value theorem then they should preferentially feed on those sugar solutions that would allow them to take up, on average, the most <span>energy per hour</span>. Now, a crow having to wrestle with opening a clam shell or a fly having to divide its precious time between feeding and mating is one thing. But you may wonder what's to stop a butterfly simply opting to feed on the most sugary solution offered every time? The answer is satisfyingly subtle: you must remember that a butterfly is constrained to having to feed through a straw! (The proboscis). If you imagine yourself being hungry but constrained to eat through a straw, you'll realise that whilst a thick gloopy syrup will certainly provide you more total energy than a thin watery one, sucking a jar of treacle through a straw is certainly no quick meal! When you realise this, an answer to the question of what sugar concentration in water will allow you to imbibe the most calories per hour is suddenly not so obvious.<br /><br />I can't help but digress at this point to briefly address the question: How <span style="font-style: italic;">do</span> you gather data on the feeding preferences of a butterfly? One option is to chase your specimen around a forest with a stopwatch! Preferable of course, is to find some way to get a captive butterfly to eat 'on demand' in the laboratory. This might sound tricky but Hawksworth provides a wonderfully simple solution that any suitably motivated amateur could replicate (naturally, you need a supply of butterflies but there are various companies on the web that will sell you eggs and caterpillars). The trick is to know that butterflies can taste through their feet! Gently hold your butterfly between thumb and finger, lower its feet into a dish of sugar water and, bingo!, it will instinctively unroll its proboscis and begin to feed. Get yourself a stopwatch and you're all ready to test the marginal value theorem!<br /><br />Anyway to return to our main question: Are the eating habits of Painted Lady's in agreement with the marginal value theorem, with butterflies eating so as to maximise their average rate of energy uptake? Interestingly, the answer seems to be no. Instead, Painted Ladies go for meals that give them the most energy<span style="font-style: italic;"> in one sitting</span> (even though it may take longer to eat such a meal). This doesn't mean the marginal value theorem is 'wrong' (as above, it applies well in some situations), it simply means that one or more of the assumptions upon which this theorem is based don't apply to the Painted Lady. One suggestion is that rather than playing the 'long game' of choosing sugar solutions that maximise the calorie intake over a long period of time, newly emerged female butterflies are keen to pack in high calorie meals early, in order that they can quickly take on board enough energy to enable them to lay a large clutch of eggs. Whether this is the full story however appears to require more study...but then of course, you, dear reader, now know how to approach the task of conducting butterfly feeding experiments. I'm entirely confident therefore, that the answers will be with us shortly!Henry Walloonhttp://www.blogger.com/profile/16370052352586546748noreply@blogger.com1