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.

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

ResearchBlogging.orgWe 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

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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?

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#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.

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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.

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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)
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Masquerading caterpillars hide in plain sight

ResearchBlogging.orgInsects 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

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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.

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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)
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