Or, you know, the evolution of a super-cold. The discovery of a new way to stop viruses after they’ve already invaded cells could lead to an actual cure for the common cold. (The Independent)
Pleistocene Park, anyone? An extremely well-preserved mammoth skeleton unearthed near Denver, Colorado, may contain reasonably intact DNA. (The Denver Post)
Not just because of running to catch the bus. People who use public transit tend to be more active in general. (Obesity Panacea)
What the !?%$#**! do we know about human mutation rates, anyway? Less than you might think. (John Hawks Weblog)
This confirms what I already believe about both anti-vaxxers and corporate PowerPoint use. A GlaxoSmithKline presentation on the importance of vaccination leaves Jason Goldman pondering cognitive bias and the vital importance of good PowerPoint use. (The Thoughtful Animal)
All part of a conspiracy by socialist Radiolarians. Analysis of carbon isotopes in sediment cores suggest that a period of climatic warming in the middle Eocene was caused by increased atmospheric carbon dioxide. (Scientific American)
WTF is hepato-splen? That’s just one of many questions Scicurious can’t answer about a truly bizarre study investigating the effect of lunar phases on women’s menstrual cycles. (Neurotic Physiology)
Video this week, via io9: German researchers have determined that bats recognize bodies of water by echolocation because, when presented with a metal plate that reflects sound the way water does, they try to drink from it.
New species form when separate populations of related organisms are no longer able to interbreed. Reproductive isolation can arise if two populations evolve different mating behaviors, or lifestyles so different that individuals from different populations don’t even encounter each other—but it need not mean that matings between the two populations never occur. In fact, speciation can arise in the face of quite a lot of interbreeding, so long as the hybrids produced by interbreeding are less fit than “purebred” individuals.
This is what seems to be occurring in populations of Edith’s checkerspot, a small butterfly native to Western North America. Checkerspot populations in California use a wide variety of different host plants, and a recent study has shown that the offspring of parents from different host plants are maladapted in the wild.
In the Sierra Nevada mountains, logging has created a new kind of habitat for Edith’s checkerspot [PDF]—patches of cleared forest where the butterfly’s locally preferred host plant, Pedicularis semibarbata, is rare or nonexistent, but an alternative host plant, Collinsia torreyi, is plentiful. In the transition between clearings and less-disturbed forest, the two plants may often grow side by side.
Examination of checkerspot populations that have access to only one of the two host plants suggests that each plant is best used in rather different ways. For instance, Pedicularis-using checkerspot females lay lots of eggs on a few plants, while Collinsia-using females lay a few eggs on each of a large number of plants. Once they hatch, larvae from Pedicularis populations feed on leaves closer to the ground than larvae from Collinsia populations, which makes sense since Pedicularis grows lower in general.
If these differences have a genetic basis, then hybrid checkerspots might exhibit intermediate behaviors, which might not work so well on either host plant. To test for this “hybrid inviability,” the new study’s authors crossed checkerspots from populations encountering only one host plant or the other, and then tested the hybrids’ performance in the field—and what they found confirms those predictions.
The Goldilocks principle—intermediate is better–doesn’t apply to hybrid checkerspots. Hybrid caterpillars foraged on leaves at an intermediate height on both host plants, and grew more slowly than purebred caterpillars. Hybrid females laid an intermediate number of eggs on both host plants, and laid them at an intermediate height. This left their offspring in a poor position for foraging after they hatched—and indeed, they grew more slowly than larvae hatched from eggs that were laid at the “traditional” heights on the host plants.
So it looks as though natural selection for better performance on Collinsia has led to the evolution of checkerspots that are at a disadvantage using Pedicularis (and vice versa). This even to the point that hybrids, which feed and oviposit in ways that are only somewhat different from the optimum, pay performance costs.
What’s interesting, though, is that this hasn’t led to greater genetic differentiation of checkerspot populations using different host plants; as assessed using randomly-selected genetic markers, there is an isolation-by-distance effect, but no effect of host plant use. (The authors cite a previous study using about 400 AFLP loci [PDF].) That suggests that only a few genes are responsible for the observed adaptive differences, and that natural hybridization between checkerspot populations using different hosts may be mixing together the rest of the genome.
References
McBride, C., & Singer, M. (2010). Field studies reveal strong postmating isolation between ecologically divergent butterfly populations. PLoS Biology, 8 (10) DOI: 10.1371/journal.pbio.1000529
Singer, M.C., & Wee, B. (2005). Spatial pattern in checkerspot butterfly-host plant association at local, metapopulation and regional scales. Annales Zoologici Fennici, 42, 347-61
The 20th edition of the Carnival of Evolution is now online at Byte Size Biology—where the compilation of evolution-themed online writing is given a sporting spin. Check it out!
In the comments on my epic post about J.B.S. Haldane, somebody else named Jeremy (not me, I swear) links to a fantastic video of Haldane’s scientific colleague (and fellow former British Communist) John Maynard Smith, discussing Haldane’s opposition to Lysenkoism. Specifically, what Haldane said in private within Communist circles, versus what he didn’t say in the broader public.
I think it’s quite clear that Haldane should have objected to the politicization of Lysenko’s bunk science much earlier and more forcefully than he did. Whether it would’ve made a difference behind the Iron Curtain is less certain.
Wow. Lots of links this week. I’m using Google Reader again, so evidently getting better at aggregation and/or wasting valuable dissertation-completion time.
Sundews catch insects on their sticky leaves, potentially putting them in competition with web-spinning spiders. Photo by petrichor.
Shape up, Dad. Female rats are more prone to develop diabetes if their fathers were obese—through an inherited metabolic disorder. (Neurotic Physiology)
Also useful for studying how lizards rebel against their creators. To study how lizards communicate, build a robotic lizard. No, really. (The Thoughtful Animal)
Sounds like the basis for a very strange odd-couple sitcom. Can a spider and a plant be competitors? Maybe, if the plant is carnivorous. (It Takes 30)
A species in the genus Rosa by any other taxonomic identifier … Rod Page contemplates the importance of taxonomic names to biological research, and how to handle them in modern data structures. (iPhylo)
Nobody could’ve predicted. BP’s cost-cutting and rapid corporate expansion probably contributed to a corporate culture prone to accidents. (ProPublica)
One more way in which sloths are weird. Almost all mammals—giraffes included—have seven vertebrae in their necks. But sloths have up to 10. A new developmental study suggests how those extra vertebrae evolved. (NY Times, h/t Mike the Mad Biologist)
Every little bit helps. A new study suggests that, without modern conservation efforts, the ongoing extinction crisis would be even worse. (Southern Fried Science)
Um. Doesn’t that defeat the purpose? Placebos are used all the time in pharmaceutical research, but very few published studies actually report what the placebo was made of. (Helen Jacques)
The salmon of doubt. The inaugural article in the Journal of Unusual and Serendipitous Results casts doubt on interpretation of functional MRI readings—when its authors find brain activity in a dead fish. (Byte Size Biology)
But it looks so cool when Don Draper does it. Dave Munger ponders the ultimate effectiveness of smoking bans and warnings. (SEED Magazine)
“Aspergirls” is one catchy neologism. Steve Silberman continues his exploration of human experience on the Autism spectrum with comedienne Rudy Simone—and opens an ongoing conversation with her at The Well. (NeuroTribes)
More sloth weirdness on video: they can swim! But the water’s a dangerous place, as David Attenborough will tell you.
Here’s a nicely gruesome image for the week of All Hallows’ Eve.
“I dreamed I was in a dark room,” said Jane, “with queer smells in it and a sort of low humming noise. Then the light came on … I thought I saw a face floating in front of me. … What it really was, was a head (the rest of a head) which had had the top part of the skull taken off and then … as if something inside had boiled over. … Even in my fright I remember thinking, ‘Oh, kill it, kill it. Put it out of its pain.’ … It was green looking and the mouth was wide open and quite dry. … And soon I saw that it wasn’t exactly floating. It was fixed up on some kind of bracket, or shelf, or pedestal—I don’t know quite what, and there were things hanging from it. From the neck, I mean. Yes, it had a neck and a sort of collar thing round it, but nothing below the collar; no shoulders or body. Only these hanging things. … Little rubber tubes and bulbs and little metal things too.”
—Jane describes the disembodied Head in That Hideous Strength
Before he started The Chronicles of Narnia, C.S. Lewis tried his hand at science fiction. Lewis’s Space Trilogy—Out of the Silent Planet, Perelandra, and That Hideous Strength—is like H.G. Wells dunked in (by modern American standards) gentle British Christianity. As in Narnia, Lewis wrote the Space Trilogy with a thesis in mind. The villains of Lewis’s imagined universe are materialistic scientists. In the first two books, the protagonist fights the scientists to preserve prelapsarian conditions among the intelligent inhabitants of Mars and Venus, respectively. The third book returns to Earth, where the evil scientists are plotting to take over the planet in the service of a demon-possessed disembodied head kept alive by technology that would’ve put Frankenstein off his lunch.
Lewis derived the scientists’ ideology, and one of the evil scientist characters in particular, from the writings and person of the evolutionary geneticist J.B.S. Haldane—which is not surprising, since Haldane was something of the Richard Dawkins of his day, a visible public advocate for the scientific worldview. What is surprising, though, is that Lewis may have had a perfectly good reason to connect Haldane to an artificially resurrected head: five years before the publication of That Hideous Strength, Haldane had narrated a film depicting just such an experiment.
But there’s no mention of the mouse who helped him. Dr. Skyskull unwinds the history of Benjamin Franklin’s famous kite experiment, drawing on original reports in Proceedings of the Royal Society. (Skulls in the Stars)
$%@!!?#! Saying an expletive aloud actually helps you tolerate pain. (Neurotic Physiology)
I’m guessing that animated tattoos will be first. Stretchable sheets of micro-electronic components will have all sorts of science-fictiony medical applications. (All that matters)
It’s an even longer way to amphioxus than we thought. MicroRNA analysis suggests that hagfish, long thought to be the most deeply-diverged relatives of vertebrates, aren’t. (Wired Science)
On the wrong track. Dave Munger suggests that the same cognitive bias revealed by the “trolly car” dilemma may underlie people’s willingness to believe pseudoscientific explanations for autism. (SEED Magazine)
Like calcium carbonate shells, scansion breaks down at low pH. The perils of ocean acidification, explained in (mostly) rhyming couplets. (Deep Sea News)
The king of the Red Queen is dead. Leigh Van Valen, originator of the Red Queen hypothesis, died last weekend. (dechronization)
There’s so many, we really ought to have some sort of systematic way to classify them. John S. Wilkins tackles species concepts. (Evolving Thoughts)
Video this week is the supplementary information for a recent study of sloth locomotion [$a] (via Wired Science)—the research found that, although they do it upside-down, sloths move a lot like other mammals.
Using specific compounds to cure disease seems like a fairly advanced behavior—it’s necessary to recognize that you’re sick, then know what to take to cure yourself, then go out and find it. You might be surprised to learn, then, that one of the best examples of self-medication behavior in a non-human animal isn’t another primate species, or even another vertebrate. It’s none other than monarch butterflies. Female monarchs infected with a particular parasite prefer to lay eggs on host plants that help their offspring resist the parasite [PDF].
Most natural monarch butterfly populations are infected, at varying rates, with the protozoan parasite Ophryocystis elektroscirrha. Monarch larvae become infected when they eat parasite spores laying on the leaves of their food plants; the parasites reproduce inside the growing larvae form more spores while the larvae undergoes metamorphosis. Infected adults emerge from their chrysalises covered in O. elektroscirrha spores, which they spread to their mates and to their own offspring.
Monarch caterpillars are well-known to eat milkweeds, which defend themselves by producing organic compounds in a class called cardenolides—literally “heart poisons.” These deter lots of insect herbivores, but monarch caterpillars have evolved physiological mechanisms to store up cardenolides without suffering ill effects, which in turn makes each caterpillar, and its later adult phase, toxic to predators. (Lots of specialist herbivores evolve tolerances to, or even preferences for, their host plants’ defensive chemistry.)
It turns out that cardenolides are also bad for monarchs’ parasites. In an experiment published in 2008, de Roode et al. raised monarch caterpillars on two milkweed species that produced differing amounts of cardenolides, Asclepias curassavica and A. incarnata. They found that infected caterpillars fed the more toxic A. curassavicasuffered fewer ill effects of infection [PDF].
This result is remarkable enough on its own. It suggests that the effects of infection by Ophryocystis elektroscirrha might vary in natural monarch populations depending on something separate from the monarch-parasite interaction itself—the toxicity of the locally-available milkweed species. But what if monarchs could choose more toxic milkweed to fight infection?
This possibility of self-medication by monarchs is the focus of the latest result in the monarch-parasite system. In the new study, a team of researchers at Emory University and the University of Michigan offered infected and uninfected monarch caterpillars leaf cuttings from both of the milkweed species used in the 2008 experiment. However, infected caterpillars showed no greater preference for the more toxic milkweed.
Caterpillars might not be well-suited to self-medication anyway; they’re not very mobile, and so stuck with the host plant patch in which they hatch. Adult female monarchs, on the other hand, can fly—and seek out a patch of parasite-fighting plants on which to lay their eggs. In a second experiment, the team offered infected and uninfected adult females the opportunity to lay eggs on a single plant of each milkweed species, placed at opposite ends of a flight cage. And, indeed, infected female monarchs looked out for the best interest of their offspring, laying a larger proportion of their eggs on the more toxic plant.
This sort of trans-generational self-medication raises some very interesting questions, particularly, how do infected monarchs know they’re infected? How does local diversity of milkweed species in natural populations alter the coevolution of monarchs with Ophryocystis elektroscirrha? There’s still a lot to learn about this fascinating behavior, which may be happening in backyards across North America.
To conclude, here’s a great video produced by Emory University, in which Principal Investigator Jaap de Roode talks about monarchs in general, and the new discovery in particular.
References
Bradley, C., & Altizer, S. (2005). Parasites hinder monarch butterfly flight: implications for disease spread in migratory hosts. Ecology Letters, 8 (3), 290-300 DOI: 10.1111/j.1461-0248.2005.00722.x
de Roode, J., Pedersen, A., Hunter, M., & Altizer, S. (2008). Host plant species affects virulence in monarch butterfly parasites. Journal of Animal Ecology, 77 (1), 120-6 DOI: 10.1111/j.1365-2656.2007.01305.x
de Roode, J., Yates, A., & Altizer, S. (2008). Virulence-transmission trade-offs and population divergence in virulence in a naturally occurring butterfly parasite. Proceedings of the National Academy of Sciences, 105 (21), 7489-94 DOI: 10.1073/pnas.0710909105
Lefèvre, T., Oliver, L., Hunter, M., & De Roode, J. (2010). Evidence for trans-generational medication in nature. Ecology Letters DOI: 10.1111/j.1461-0248.2010.01537.x
Lucky for them, they never invented jet travel. Sea anemones—whose common ancestor with humans lived about 600 million years ago—possess some of the same physiological features that give us our circadian rythym. (Dave Munger for SEED Magazine)
Gesundheit! A universal flu vaccine may be possible, in the not-too-distant future. (Virology Blog)
Being somewhat wrong is better than knowing nothing at all. Estimates of the rates at which species arise based on phylogenies still work pretty well if there is uncertainty or error in the phylogeny. (dechronization)
Oy.Nature‘s science news feature mistakenly refers to platypuses (platypi? platypodes?) as marsupials. (The Tree of Life)
Fossil forests! In commemoration of Wednesday’s National Fossil Day, Anne Jefferson presents a virtual field trip to the John Day Fossil Beds in eastern Oregon. (Highly Allochthonous)
To be fair, hoverflies are not very bright. Orchids pollinated by aphid-feeding hoverflies smell like aphids. (LabSpaces)
Together, we realized that we’d never seen a Coming Out Day feature dedicated to the experiences of lesbians, gay men, bisexuals and transgendered persons in the sciences and engineering. Science journalist powers: Activate! We hope today’s two-part celebration will add to the diversity of stories and help science-minded young queer folks everywhere know that it does, indeed, get better—both through the course of history, and the course of an individual’s life.
Other queer scientists are invited to contribute stories in the comments of Maggie’s piece. (Maggie asked me to help contact people to share their stories, and I put her in touch with Dr. Futuyma; and Steve was kind enough to give me a nod at the end of the cross-post of his interview with Neena Schwartz.)
Photo by rpongsaj.
