Science online, independently-evolved sonar edition

Photos by Thomas Hawk and Tolka Rover.

Whether you're doing it underwater or in the air, echolocation apparently requires the same kind of adaptation. New Scientist reports that parallel evolutionary changes to the same gene allow both dolphins and bats to hear the high-frequency sounds they use for sonar. In other online science news:

• Eutrophication of lakes reduces the diversity of invertebrate species they support. (Conservation Maven)
• Real-time video of viruses spreading among host cells. Seriously. (Ed Yong's twitter feed)
• A long-term survey of bird species diversity finds that sites on an active military base look pretty much like sites that see less, um, artillery. (Conservation Maven, again)
• Close examination of fossilized feathers provides the first evidence for striped dinosaurs. (Carl Zimmer for the New York Times, Not Exactly Rocket Science, NPR)
• The human foot absorbs the stress of running more effectively when not encased in a supportive sneaker. (NPR)

"Chemical camouflage" lets leafhoppers hide from their own bodyguards

Many insects in the order Hemiptera – the "true" bugs – have evolved a way to hire their own protection by excreting sugary "honeydew." Honeydew attracts ants, who tend honeydew-producing bugs like livestock, protecting them from predators and even disease. Honeydew is cheap to make because honeydew producers typically make a living sucking the sap of their host plants; they're trading sugar and water, which they have in abundance, for safety.

Camponotus crassus ants protect Guayaquila xiphias leafhoppers, apparently mistaking them for part of their host plant. Detail of Silveira et al., figure 1.

But there's a catch. Ants make good bodyguards because they are carnivorous – and they're perfectly willing to start eating their flock. A natural history note in the latest issue of The American Naturalist suggests that one group of ant-protected bugs deals with this problem by cloaking themselves in chemicals that make the ants think they're part of the host plant [$a].

The study's authors determined that organic compounds on the cuticle of the honeydew-producing leafhopper Guayaquila xiphias, which is often tended by the ant Camponotus crassus, were similar to compounds on the surface of the leafhoppers' preferred host plant. They presented ants with freeze-dried leafhoppers whose cuticles were washed clean with solvent, and found that the ants were much more likely to attack washed leafhoppers than unwashed ones; the ants were also more likely to attack leafhoppers they found on plants other than the preferred host. Finally, the authors replicated the earlier experiments using moth larvae coated with leafhopper cuticle compounds, and found that the "chemical camouflage" conferred the same protection on a different insect species.

This neat result shows how hazardous honeydew-producers' relationship with their ant bodyguards can be – they have to hide from the ants even as they offer them an inducement to stick around!

Reference

Silveira, H., Oliveira, P., & Trigo, J. (2010). Attracting predators without falling prey: Chemical camouflage protects honeydew‐producing treehoppers from ant predation The American Naturalist, 175 (2), 261-8 DOI: 10.1086/649580

Cane Toads!

Cane Toads: An Unnatural History is a film that seems almost engineered for geeky cult status. It's an Australian documentary about one of the most graphic examples of an invasive species, the cane toad Bufo marinus, which was introduced to the continent to control cane beetle grubs. This didn't work out exactly as planned – the extremely fecund toads have swarmed over northeastern Australia, eating everything they can catch, killing most things that catch them (they're poisonous), and not eating cane beetle grubs.

The documentary describes this ecological disaster, and Australians' wildly varied responses to it – from treating the toads as pets to slaloming across the pavement so as to road-kill as many as possible – with a sort of wry glee. Delightfully, it's all on YouTube. Even more delightfully, there is a brand-new sequel, in 3D.

That's right. Cane toads. In 3D.

No word on a U.S. general release date, but I'll be keeping an eye out. This has me way more excited than Avatar ever did. In the meantime, here's the first ten minutes of the original. Just imagine the added depth this will have, when you're wearing the silly glasses in front of an Imax screen.

Science online, share and share alike edition

Wednesday saw Greta and Dave Munger turn off the virtual lights at Cognitive Daily after five years of high-quality, and often participatory, science writing. No other science blog that I know regularly asked its readers to join studies, however informal, of the very concepts it covered – not just writing about science, but practicing it. It's sad to see it end, but I'm looking forward to the new project Dave teases at the end of the announcement. Elsewhere in the science blogosphere:

Photo by Gary Simmons.

• Europe's fisheries aren't likely to recover by 2015, as planned under a 2002 treaty. (Conservation Bytes)
• The American Naturalist will begin requiring authors to deposit all data, not just genetic sequences or phylogenetic trees, in publicly-accessible online repositories. (skeetersays)
• Shorebirds may migrate in part because there are fewer nest predators at higher latitudes. (Living the Scientific Life)
• Natural selection imposed on native species by invasive species might make prairie grass communities better able to resist new invasions. (Conservation Maven)
• Lemurs might have colonized Madagascar by rafting on driftwood – a new model of ocean currents shows that it might have been easier than previously thought. (Laelaps)

Evolving from pathogen to symbiont

Recently the open-access PLoS Biology published a really cool study in experimental evolution, in which a disease-causing bacterium was converted to something very like an important plant symbiont. The details of the process are particularly interesting, because the authors actually used natural selection to identify the evolutionary change that makes a pathogen into a mutualist.

Life as we know it needs nitrogen – it's a key element in amino acids, which mean proteins, which mean structural and metabolic molecules in every living cell. Conveniently for life as we know it, Earth's atmosphere is 78% nitrogen by weight. Inconveniently, that nitrogen is mostly in a biologically inactive form. Converting that inactive form to biologically useful ammonia is therefore extremely important. This process is nitrogen fixation, and it is best known as the reason for one of the most widespread mutualistic interactions, between bacteria capable of fixing nitrogen and select plant species that can host them.

Clover roots, with nodules visible (click through to the original for a nice, close view. Photo by oceandesetoile.

In this interaction, nitrogen-fixing bacteria infect the roots of a host plant. In response to the infection, the host roots form specialized structures called nodules, which provide the bacteria with sugars produced by the plant. The bacteria produce excess ammonia, which the plant takes up and puts to its own uses. The biggest group of host plants are probably the legumes, which include the clover pictured to the right, as well as beans – this nitrogen fixation relationship is the reason that beans are the best source of vegetarian protein, and why crop rotation schemes include beans or alfalfa to replenish nitrogen in the soil.

For the nitrogen-fixation mutualism to work, free-living bacteria must successfully infect newly forming roots in a host plant, and then induce them to form nodules. The chemical interactions between bacteria and host plant necessary for establishing the mutualism are pretty well understood, and in fact genes for many of the bacterial traits, including nitrogen-fixation and nodule-formation proteins thought to be necessary to make it work are conveniently packaged on a plasmid, a self-contained ring of DNA separate from the rest of the bacterial genome, which is easily transferred to other bacteria.

This is exactly what the new study's authors did. They transplanted the symbiosis plasmid from the nitrogen-fixing bacteria Cupriavidus taiwanensis into Ralstonia solanacearum, a similar, but disease-causing, bacterium. With the plasmid, Ralstonia fixed nitrogen and produced the protein necessary to induce nodule formation – but host plant roots infected with the engineered Ralstonia didn't form nodules. Clearly there was more to setting up the mutualism than the genes encoded on the plasmid.

Wild-type colonies of Ralstonia (tagged with fluorescent green) are unable to enter root hairs (A), but colonies with inactivated hrcV genes are able to enter and form "infection threads," like symbiotic bacteria (B). Detail of Marchetti et al. (2010), figure 2.

This is where the authors turned to natural selection to do the work for them. They generated a genetically variable line of plasmid-carrying Ralstonia, and used this population to infect host plant roots. If any of the bacteria in the variable population bore a mutation (or mutations) necessary for establishing mutualism, they would be able to form nodules in the host roots where others couldn't. And that is what happened: three strains out of the variable population successfully formed nodules. The authors then sequenced the entire genomes of these strains to find regions of DNA that differed from the ancestral, non-nodule-forming strain.

This procedure identified one particular region of the genome associated with virulence – the disease-causing ability to infect and damage a host – that was inactivated in the nodule-forming mutant strains. As seen in the figure I've excerpted above, plasmid-bearing Ralstonia with this mutation were able to form infection threads, an intermediate step to nodule-formation, where plasmid-bearing Ralstonia without the mutation could not. Clever use of experimental evolution helped to identify a critical step in the evolution from pathogenic bacterium to nitrogen-fixing mutualist.

References

Amadou, C., Pascal, G., Mangenot, S., Glew, M., Bontemps, C., Capela, D., Carrere, S., Cruveiller, S., Dossat, C., Lajus, A., Marchetti, M., Poinsot, V., Rouy, Z., Servin, B., Saad, M., Schenowitz, C., Barbe, V., Batut, J., Medigue, C., & Masson-Boivin, C. (2008). Genome sequence of the  beta-rhizobium Cupriavidus taiwanensis and comparative genomics of rhizobia. Genome Research, 18 (9), 1472-83 DOI: 10.1101/gr.076448.108

Gitig, D. (2010). Evolving towards mutualism. PLoS Biology, 8 (1) DOI: 10.1371/journal.pbio.1000279

Marchetti, M., Capela, D., Glew, M., Cruveiller, S., Chane-Woon-Ming, B., Gris, C., Timmers, T., Poinsot, V., Gilbert, L., Heeb, P., Médigue, C., Batut, J., & Masson-Boivin, C. (2010). Experimental evolution of a plant pathogen into a legume symbiont. PLoS Biology, 8 (1) DOI: 10.1371/journal.pbio.1000280

Blogging the white sands

While out of town for Science Online, I got word of a new blog worth following – two other University of Idaho doctoral students, Simone DesRoches and Kayla Hardwick, have started writing about a self-directed course they've set up at The Evolutionary Ecology of White Sands, NM.

Simone and Kayla will be reading three classic evolutionary ecology texts, Dolph Schluter's Ecology of Adaptive Radiation, Jerry Coyne and Alan Orr's Speciation, and Robert MacArthur's Geographical Ecology, and discussing them in the context of their research on the lizards of White Sands, New Mexico. Three distantly related species have all evolved white coloration after colonizing a region of white gypsum sands, each via a different genetic mechanism. (For more details, see Ed Yong's excellent recent article about the White Sands lizards.) It's a fascinating system, and the three books should make a great jumping-off point for discussing what's known about it and what's yet to be learned.

The white sands. Photo by Fabian A.M.

Research Blogging Awards 2010

On the heels of Science Online 2010, the ResearchBlogging.org community has announced the Research Blogging Awards, honoring online writing about peer reviewed research in a wide range of categories. Nominations are open until 11 February, and can be submitted by anyone; a panel of judges will select 5 to 10 finalists from nominees in each category, and winners will be selected by a vote of the RB.org membership.

#scio10 day three: In which the discussion of online civility remains (almost) entirely civil

Sunday morning, the final sessions of Science Online 2010 seemed almost planned to tie together the broad theme of the conference – how best to connect science (and working scientists) with the rest of society.

Broader impact done right: A heavily marine-themed panel – Karen James of the Beagle Project, Deep Sea blogger Kevin Zelnio, Miriam Goldstein of the Oyster's Garter, the New England Aquarium's Jeff Ives and NASA's Beth Beck – discussed a wide range of science outreach options available, mostly from the perspective of working scientists.

A consensus emerged that good outreach, of which online resources are now usually a part, is essential to basic research, and will be increasingly important in obtaining funding. Funnily enough, my collaborator Chris Smith had just e-mailed me about the possibility of bringing a satellite broadband connection with us for the upcoming field season – maybe we'll be live-blogging Joshua tree research this year.

Article-level metrics: Peter Binfield, the managing editor of PLoS ONE, discussed the ways in which PLoS is now measuring the impact of individual articles published through its online, open-access journals – not just citation counts, but also pageviews, PDF download rates, and the recent collaboration with ResearchBlogging.org to track blog coverage. It's clear that research articles aren't going to be judged by the impact factor of their containing journals anymore, now that you get a citation count with every Google Scholar search, and it'll be interesting to see what scheme emerges as global standard for article-level impact.

Online civility: Science bloggers Janet "Dr. Freeride" Stemwedel, Sheril Kirshenbaum, and the pseudonomous Dr. Isis led discussion about what constitutes civil behavior in an online setting – and the conversation turned into something of an object lesson, as disagreement over the meaning of civility itself turned, well, very nearly un-civil. The panel did, I thought, an admirable job demonstrating in "real life" the skills necessary for online moderation of touchy discussions.

I wouldn't say there was consensus, but the room did seem to come together around the ideas that communities define their own standards of civility, that those very standards can make it difficult to express minority or dissenting points of view, and that (judicious) incivility can be useful for minorities trying to be heard. Dave Munger made that last point, and I hope my paraphrase does it justice – I think it's an important one. Certainly it's the case that sexual minorities have been (and still are – I'm looking at you, Mennonite Church USA) told that merely acknowledging our existence and discussing our perspective is a violation of civility, inasmuch as "civil" is equivalent to "suitable for general audiences." It was a great discussion, and I'm still processing it – it might be worth a dedicated post in the near future.

So now I'm sitting in the Raleigh-Durham airport, writing up the weekend over dodgy, overpriced WiFi – I've been badly spoiled by SignalShare's fantastic service. Many, many thanks to organizers Bora Zivkovic and Anton Zuiker, and to the sponsors, who put on a fantastic conference – and especially to NESCent, who made it possible for me to attend. It was a great time!

#scio10 day two: In which the discussion turns to duck genitalia within the second session

Science Online is not like the Evolution meetings. This was evident in the first session I entered, where the plastic click of laptop keys underlay the conversation between the panelists and the audience. Twitter was a second venue for discussion the whole conference, and you could track audience interest in a given session purely from posts with the #scio10 hashtag. Notes on the sessions I attended:

• From blog to book: Tom Levenson, Brian Switek, and Rebecca Skloot discussed the usefulness of blogging for authors and developing authors, mostly as a venue for promoting books, but also as a space for developing ideas and writing to develop a book.
• Rebooting science journalism: Ed Yong, Carl Zimmer, John Timmer, and David Dobbs led discussion about the future of science journalism online, with emphasis on unique ways to connect the diverse and Balkanized interest groups of the web to science news, and an extensive aside on the recently discovered role of sexual selection in the morphology of ducks' penises and vaginas – Carl wasn't able to publish much detail via a print magazine, but (perhaps unsurprisingly) the story proved popular online. This set off a flurry of interest in the article in question, and revealed I'm not the only one who thought this phenomenon makes limerick fodder.
• Demonstrations of a new German science magazine for children, an online hub for New Zealand-centric science reporting, use of Second Life as a science education resource, and the Open Dinosaur Project. I wasn't strongly impressed by the Second Life presentation – I don't see the usefulness of the 3-d environment over conventional instant messaging. On the other hand, Andy Farke's Open Dinosaur Project is doing amazing things with a bunch of volunteer "citizen scientists" assembling a morphological data from the literature. It's a new model for digging data out of old publications, and it's not hard to think of other projects that could benefit from a similar approach.
• An open history of science: John McKay and Eric Michael Johnson discussed the history of media employed in scientific societies. Turns out that Enlightenment-era scientists corresponding by mail, the informal science societies they formed, and the journals they compiled from each others' letters were more like the modern blogosphere than you might think.
• Online reference managers: representatives from Citeulike, Mendeley, Zotero, and Scopus talked about their various products' approaches to organize researchers' electronic reference libraries, and to use personal contacts and library content to recommend new material. There's some interesting possibilities – enough that I've downloaded Mendeley (the only one, so far as I could tell, that has a locally-installed client) to play around with for a bit. I'd love to ditch EndNote, if I can extract my thousands of references and linked files without too much bother.

The day concluded with a banquet at the hotel, capped by a series of brief "ignite" talks on everything from the benefits of blogging while working toward tenure to a crowd-sourced project to check the accuracy of chemistry information in online sources.

Here's a slideshow of photos uploaded to Flickr with the #scio10 tag, mostly from Saturday if I'm not mistaken.

#scio10 day one: NESCent!

As one of the recipients of the Science Online travel awards, I spent Friday morning, and lunch, visiting National Evolutionary Synthesis Center. NESCent is an NSF-funded space where postdoctoral fellows and faculty members on sabbatical are put together with an unlimited supply of coffee to apply new analyses to (mostly) existing datasets, often in collaboration with researchers at Duke University, the University of North Carolina, or North Carolina State University, the three institutions administering the center.

In three and a half hours, I met with (in no particular order) Craig McClain, Robin Smith, Carlos Botero, Julie Meachen-Samuels, Ben Redelings, Trina Roberts, Juan Santos, and Gregor Yanega – it was extremely stimulating, and a little dizzying. (The other travel award winner, Christie Wilcox, arrived later in the morning, straight off her multi-connection flight from Hawaii, but she held up remarkably well.) The visit wrapped up with lunch at a nice cafe across the street from the NESCent offices, and then it was off to the lemurs with me. I can't think of a better way to start the conference than a morning packed full of smart people doing interesting science.

Update, 17 Jan 2010: Christie took a couple photos, one of which I'm posting here:

Welcomed by NESCent. Photo by Christie Wilcox.

#scio10 day one: Duke Lemur Center

Having a blast at Science Online 2010 – too much to write about in the time I can grab between sessions. But it turns out that Flickr has lots of good photos from the Duke Lemur Center, which I toured yesterday afternoon. It was really cool, so here they are.

Science online, fried couch potato edition

Photo by Kevin Steele.

Yes, I'm presently at Science Online 2010, but there's no rest for the Interwebs.

• Kill your TV, before it kills you: Watching more than an hour of television a day may counteract the benefits of regular exercise. (Dave Munger at SEED)
• Divorce rates are higher in states with same-sex marriage bans. Correlation, or causation? "It could be that voters who have more marital problems of their own are more inclined to deny the right of marriage to same-sex couples." (FiveThirtyEight.com)
• Artificial selection of food plants doesn't reduce their genetic diversity, it turns out. (Agricultural Biodiversity Weblog)
• Prairie dogs help prevent invasive plants from invading. (Conservation Magazine)
• Circumcision changes the bacterial community of the penis – and reduces the presence of species that can cause bacterial vaginosis. (Mike the Mad Biologist)
• The evolution of avian influenza depends more on local dynamics than on long-distance migration events. (Mystery Rays from Outer Space)
• Farmed salmon released in Scotland swim for Norway. (Conservation Maven)
• In Fiji, tilapia escaped from fish farms are probably preying on native fish. (Observations of a Nerd)

And, finally, via kottke, beautiful footage paired with unsettling statistics.

Why make your own food when it doesn't pay?

We humans like to think we're pretty complex – what with having invented the wheel, wars, New York, and so on – so we tend to forget that evolution doesn't care about complexity. All that matters to natural selection is who makes the most babies, and sometimes complex adaptations can get in the way of that criterion. A study recently published on the always open-access PLoS ONE provides a good example of this principle in action – given the right selective pressures, photosynthetic organisms will give up on the whole photosynthesis thing.

Tiny Indianpipe (Monotropa) and giant Rafflesia, two plants that gave up photosynthesis. Photos by Bemep and Tamara van Molken.

Photosynthesis is clearly a complex adaptation, requiring specialized cellular structures and biochemical processes that can use light to power the synthesis of sugars. Complex enough for a whole additional organism, in fact, since the chloroplast, the cellular structure in which most eukaryotes conduct photosynthesis, probably originated as a symbiont that never left its host cell [$a]. (In some organisms, this process of becoming photosynthetic is still underway.) There are clear advantages to the ability to make your own food conferred by photosynthesis. Yet there are numerous examples of non-photosynthetic organisms with photosynthetic ancestors. For instance, plants as varied as the big, exotic Rafflesia or Monotropa, whose small white flowers are easy to spot in North American woods, have inactive chloroplasts and parasitize other plants. These cases are good reason to think that there may be selective conditions in which the cost of maintaining the mechanisms of photosynthesis outweighs the benefit of independent food production.

The new paper describes just such a set of selective conditions. The authors build a mathematical model of competition between microorganisms, such as flagellates, that can either be mixotrophs, able to conduct photosynthesis or capture prey to feed themselves, or heterotrophs, only able to sustain themselves by eating other critters. The model's result hinges on two key facts of life for single-celled predators: (1) it turns out that the size of a flagellate cell determines what size of prey it is best able to capture [$a]; and (2) chloroplasts take up space in a cell, limiting the evolution of cell size.

The relative advantage of retaining photosynthesis, then, is directly related to the size range of available prey. Mixotrophs, whose cells are big enough to accommodate chloroplasts, are most efficient predators of larger prey; with no chloroplasts, heterotrophs can be small enough to take advantage of smaller prey. The question of which form wins out, then, relies on the distribution of available prey sizes and the light environment. If there's lots of light for photosynthesis, mixotrophs can out-compete heterotrophs even if they don't hunt very efficiently; but if there's not much light and mostly small prey, the more efficient heterotrophs win.

The fact is, it's rare for any given adaptation to be useful under all possible conditions. Biological structures or metabolic processes that become disused are no longer under selection for efficient performance of their original function – they are free to accumulate mutations that may make them degenerate into uselessness, or to be co-opted for entirely new functions. But if an adaptation is actually costly to maintain, then natural selection may eradicate it altogether.

References

de Castro, F., Gaedke, U., & Boenigk, J. (2009). Reverse evolution: Driving forces behind the loss of acquired photosynthetic traits. PLoS ONE, 4 (12) DOI: 10.1371/journal.pone.0008465

Hansen, B., P. K. Bjornsen, & P. J. Hansen (1994). The size ratio between planktonic predators and their prey.
Limnology and Oceanography, 39, 395-403

McFadden, G. (2001). Chloroplast origin and integration Plant Physiology, 125 (1), 50-3 DOI: 10.1104/pp.125.1.50

On paywalls

Via the Daily Dish: the Economist thinks 2010 will be the year that online newspapers and magazines start erecting paywalls between their content and the rest of the web. Sullivan doesn't buy it (no pun intended):

Paywalls kill off critical interaction with the wider blogosphere and reduce readership drastically. I can see why media moguls might want the paywalls as some kind of replacement for all the power and money they have lost over the last decade. But I fear that the moment has passed.

But it occurs to me that, as someone who routinely blogs about science, I'm actually already working the way that more general news sites like the Dish might in a paywall-heavy environment – I frequently link to pages that contain only an abstract of the source article and a link via which you can pay some ridiculous figure for one-time access. The scientific journals to which I link are far more expensive than the New York Times will ever be. Yet I, and a lot of much more successful science-focused bloggers, are doing OK, and people are learning about new scientific results through our (mostly their) writing, probably mostly without ever clicking through for the original articles. That wouldn't work for the New York Times.

So why does it (kinda, sorta) work for scientific journals? (1) Maybe most of my readers are academics, with institutional subscriptions to carry them past those links with the [$a] tags. (2) Maybe those of my readers who don't have institutional subscriptions don't count as lost revenue for the journals, because they're people who would never buy a copy of Systematic Biology on a newsstand if they could. (3) There's PLoS, and open-access has lots of promise as a model – maybe they'll start to win out as blog coverage becomes more important as an impact metric?

#scio10: Skepticism != cynicism

In preparatory remarks for a Science Online session about trust and critical thinking, Stephanie Zvan makes a point that isn't made often enough:

You’ve met them. “Oh, those scientists. They get their funding from the government/industry/political think tanks. They’re just producing the results needed to keep their money flowing. They’ll say anything it takes. Besides, it’s not like they don’t make mistakes. Even Newton and Einstein had it wrong.”

You’ve met the others, too. “My friend told me about an Oprah show where she talked to a writer who explained how the universe really works. I always knew it was a special place made just for me.”

There’s no polite way to say it, but it can be said simply. They’re both doing it wrong.

The point being that the opposite of complete credulousness – cynicism – is not the same thing as skepticism. I see the term "skeptic" used as a synonym for "cynic" all over the place. But they're not the same thing at all – the cynic is the guy in Zvan's first example, who trusts nothing at all. A skeptic, on the other hand, does trust, given justification. Skepticism is positive; it believes that there are knowable answers to factual questions, and that human brainpower can deduce them. A skeptic may rarely decide that a given answer is the final word on a question, but that's not at all the same thing as rejecting the possibility of a useful answer.

And here we have Idaho

Bruce Reed:

Over New Years', Coeur d'Alene made national news when the barista at a roadside espresso stand thwarted an armed robbery by pulling out the pistol her husband had given her for Christmas. In a true Twin Peaks moment, the teenage robber was arrested by a deputy sheriff who had just picked up his morning coffee at the same place moments earlier.

That pretty much encapsulates the neck of the woods I live in – the trappings of the Pacific Northwest (viz, ubiquitous drive-through espresso joints) mingled with the last dregs of the Wild West. Twin Peaks is closer to being a documentary than anyone from other parts of the country can ever understand.

Science online, stuck in the Felsenstein Zone edition

Gray crowned rosy-finch. Photo by jroldenettel.

• Bayesian methods for reconstructing evolutionary relationships between species may be susceptible to errors created by long branch attraction – one of the problems they were supposed to solve. (dechronization)
• When introduced trout compete for food with gray-crowned rosy-finches, the rosyfinches lose. (Conservation Maven)
• The success of an invasive plant depends on the kind of habitat it's invading, and how that habitat is managed by humans. (The EEB & flow)
• New fossils are the earliest-known vertebrate footprints on land – 395 million years old. (Not Exactly Rocket Science, Laelaps, Pharyngula, and Palaeoblog)
• Give a meteorologist a green screen, and he'll tell you tomorrow's forecast. Give a meteorologist professional certification, and he'll tell you that climate change is a hoax. (Columbia Journalism Review)

Masquerading caterpillars hide in plain sight

Insects that have evolved elaborate mimicry of inanimate objects – leaves, twigs, even bird droppings – to hide from predators are a staple of nature documentaries. But do these masquerades work because they help insects blend into the background, or because predators actually see the insects and then dismiss them as inedible leaves, twigs, or bird droppings? It's a tricky question to answer, but a brief paper in this week's Science presents an experiment that tries to do just that [$a].

The paper's authors reasoned that if mimicry-based camouflage works through disguise rather than invisibility, a predator's experience might determine their response to mimic camouflage. They trained three experimental groups of young domestic chicks by introducing them into trial arenas containing either natural hawthorn branches, empty arenas, or hawthorn branches wrapped in purple thread. The wrapped branches were used to test whether the chicks would be more or less likely to attack something twig-like but differently colored (though this is only clear from the supplementary online material).

Larva of the brimstone moth Opisthograptis luteolata, looking distinctly twig-like. Photo by Michael E. Talbot.

The authors then presented chicks from each "training" group with either one of two species of hawthorn-twig-mimicking moth larvae (the brimstone moth, or the early thorn moth), or a hawthorn twig about the size of a caterpillar. Chicks that had previously encountered natural twigs waited longer to attack the caterpillars than chicks that hadn't previously seen twigs, or that saw the colored hawthorn branches. So, apparently, the chicks were reasoning (inasmuch as chicks reason) that the twig-like object in front of them was the same as the inedible twigs they had tried before.

This is an elegant experimental test of the effect of mimicry as mimicry – what the authors propose to call camouflage by "masquerade." However, it doesn't actually show that what the authors term camouflage by crypsis – blending into the background – isn't also contributing to the benefits that these caterpillars receive from their unique shape and coloration. There's no reason to think that twig-shaped caterpillars can't benefit in both ways, by being less visible in the first place, and then easily mistaken for a twig if they are seen.

In conclusion, here's some video footage of another natural mimic, the leaf insect.



Reference

Skelhorn, J., Rowland, H., Speed, M., & Ruxton, G. (2010). Masquerade: Camouflage without crypsis Science, 327 (5961), 51 DOI: 10.1126/science.1181931

State of the blog, 2009

I really started taking this blogging thing seriously about mid-way through 2008, when I became a member of Research Blogging. But 2009 is the first entire year I've spent actually thinking about what I'd like to write about on here, what place blogging occupies in the hierarchy of my to-do list, and what the point of the whole operation might be. So the end of the year (or really, till I finish this post, the beginning of 2010) seems like a good moment to pause and take inventory. Plus, it'll give me a page to link to for some vital stats I'd like to read into the record.

Weekly visitors to D&T, tabulated by Google Analytics. Blue line: total visitors. Orange line: visitors referred via links from other sites.

• In 2009, I wrote 229 posts (averaging just over 19/month), which drew 14,045 unique visitors (averaging 1,170/month) as tabulated by Google Analytics.
• Most visitors who didn't come directly to D&T linked here via Research Blogging or its widget on ScienceBlogs.com. I wrote 62 posts on peer-reviewed research for the Research Blogging aggregator, and these received 1,989 visitors via RB or SB. Other major referral sources include the Evolution 2009 blog coverage page (1,081 visitors) and the blogroll over at The EEB & Flow (1,027 visitors).
• I also joined the Nature Blog Network this year. NBN has been less a source of traffic, and more useful for its reminders about upcoming blog carnivals and suggestions for casual bloggers.
• I covered the Darwin 200 festivities leading up to, and throughout, the week of 12 February.
• I also blogged about the Evolution 2009 meetings, which were hosted by my department at the University of Idaho. I ran the conference website, and attempted to coordinate online activities to coincide with the meatspace meeting, with mixed success.
• This was also a year of political furor, in the States if not elsewhere, and I wrote 34 posts tagged "politics". I did not apply that label to my brief note on Barack Obama's inauguration as President.
• I've continued to write about Christianity on D&T, but only composed 13 posts with that tag, and only 2 posts about Mennonites specifically. This reflects, I think, my present relationship to the tradition in which I was raised. I don't subscribe to the supernatural elements of orthodox Christian doctrine, and the Mennonite Church as an institution doesn't seem interested in my company for, um, other reasons (although there are hopeful signs). Time for a change to the masthead? We'll have to see.
• I made $35.40 in commissions on those nerdy t-shirts of my own design advertised in the sidebar. I will not be quitting my day job any time soon.
• As an extremely pleasant end-of-year surprise, I was also awarded a travel grant for the Science Online 2010 conference, in recognition of a particularly involved post I wrote back in August about the evolution of milk drinking by adult humans. I'm looking forward to the conference and shall, naturally, cover it here.

Which observation brings this post to a tidy narrative end. I remain, I think, a scientist who has a blog rather than a science blogger, though the line between the two is blurry. Like any single-author publication, D&T is a horribly narcissistic enterprise – to me it's serving a useful function if it provides regular writing practice, structure for my extracurricular science reading, and a place to blow off steam. I've been very fortunate this year to garner the occasional comment, some very kind in-person remarks from readers I've happened to meet in person, and an opportunity to start 2010 with a conference full of smart people who are way better at this sort of thing than I am ever likely to be. Not too bad, as hobbies go.

Science online, disappearing sea lions edition

Gone for good, or just for lunch? Photo by Leo Reynolds.

Happy New Year! In case it wasn't previously obvious that I write these posts in advance, here's the proof.

• In ant-plant relationships, plants seem to be in charge: they cheat! (Thomas's Plant-Related Blog)
• Bats eat mosquitoes – but do they control mosquito populations? (Cheshire)
• The sea lions of San Francisco's Pier 39 have abandoned their post, for no readily apparent reason. No word on whether anyone has found a note reading "So long, and thanks for all the fish," but plans to commemorate the 20th anniversary of the sea lions' arrival this January are in question (Wired Science and NY Times)
• Good news: a new long-term study confirms that creating marine protected areas allows overfished ecosystems to recover. Bad news: marine protected areas are more likely to be set up in areas that aren't very economically important. (Conservation Maven)
• After colonizing a region with brilliant white, gypsum sands, three different desert lizard species evolved white skin – but each species evolved a different genetic mechanism to do so. (Not Exactly Rocket Science)
• A bat was found in France carrying the same fungus that seems to be killing bat colonies across eastern North America – but only one bat, and it seems to be healthy. (Effect Measure)