A bowhead whale’s highly (but not entirely) reduced pelvis. Image via Wikimedia Commons.
Thanks to a remarkably good fossil record, it’s now well established whales and dolphins evolved from land mammals, their forelimbs adapting into flippers, and their hind-limbs almost entirely disappearing. If you’d asked me yesterday what’s going on with that almost—the last vestiges of the hip bones that whales retain, which have no legs to support or direct contact with the rest of their skeletons—I’d have told you they were evolutionary leftovers, and probably going to disappear in another million years or so. I think a lot of other evolutionary biologists (those who aren’t whale specialists, anyway) would’ve agreed with me. But it turns out we’d have been wrong.
As Carl Zimmer describes, a paper recently published in the journal Evolution points out that whales’ hips do have one remaining function, an important one—they anchor muscles that control the penis. And that function is under ongoing sexual selection.
The more promiscuous a [whale] species was, the bigger its pelvis bones tended to be. The scientists also found that as whales evolved to become more promiscuous, their pelvic bones changed shape. These changes weren’t part of some general change to their skeleton, however. The ribs near the hips didn’t show the same patterns of size and shape change.
I strongly recommend Zimmer’s whole article, and you can also read the original research article in Evolution.
As a follow-up to CJ’s post about hummingbird moths—more generally known as hawk moths—let me recommend this episode of Plants are Cool, Too, which features the work of Chicago Botanic Garden conservation scientist Krissa Skogen. At White Sands National Monument, Skogen tracks the nectar rewards that attract hawk moths, and how far the moths carry pollen.
Well, it had to happen some time, I guess. A friend tagged me on Facebook in the “ice bucket challenge” to raise funds for the ALS Association. It’s gone massively viral: post a video of yourself getting soaked in ice water, donate to ALSA, and nominate more folks to do the same. So far, it’s raised more than $70 million, and it’s not slowing down yet.
My grandfather died of ALS, so I’m all in favor of funding research to find a cure. But as a working biologist, the idea of financing research in spurts of social media enthusiasm worries me a little. As Felix Salmon notes at Slate:
You need to fund scientists year in and year out; throwing a large grant at them in 2014 and then going away would probably end up causing more harm than good. As a result, most of this money will (and should) probably end up simply sitting on the ALS Association balance sheet, maybe earning some modest rate of interest, getting doled out very slowly over many years.
In terms of bang for the buck, then, giving money to the ALS Association is not much better than giving it to Harvard. Rather than being front-loaded and effective, it’s going to be back-loaded and (sadly, given the results of the $100 million that the ALS Association has spent to date) probably ineffective.
The real foundation of science in the U.S. is funding agencies like the National Science Foundation and the National Institutes of Health. And those agencies have had a rough decade.
Urbanization is one of the most dramatic changes humans make to natural habitats. Cities are concentrations of tall buildings, paved landscape, air pollution, and everything else that we do to make life easier for ourselves. But some living things do quite well in these highly altered conditions—think rats and cockroaches, but also red foxes and crows. As the Popular Science blog Eek Squad notes, there’s a new entry on that list: golden orb spiders, Nephila plumipes.
Lowe and colleagues found the city-dwelling arachnids were bigger than their country kin, and the most fertile spiders were found in neighborhoods with the highest socioeconomic status.
Why? The most likely explanation is that cities are warmer, which can lead to bigger invertebrates, and there’s more prey available. The latter is partly because of leaf litter and food for the prey, but it’s also because of a city-related scourge: Artificial light at night. Large spiders were found nearby, or living on, structures like light posts. Insects are drawn to sources of light at night, which could mean more meals for spiders living under bright lights in the big city.
Note that this isn’t necessarily an evolutionary change in response to urban habitats—the spiders probably just find conditions much more favorable in the city, and grow bigger as a result. But that change in resource availability could certainly lead to evolutionary changes over the long term. Go check out the whole Eek Squad post, and have a look at the original scientific article, which is freely available on PLOS ONE.
Okay, I’m paraphrasing in that headline, but only barely. From Science Insider:
A best-seller by former New York Times science writer Nicholas Wade about recent human evolution and its potential effects on human cultures has drawn critical reviews since its spring publication. Now, nearly 140 senior human population geneticists around the world, many of whose work was cited in the book, have signed a letter to The New York Times Book Review stating that Wade has misinterpreted their work.
The letter is online, and it doesn’t mince words:
Wade juxtaposes an incomplete and inaccurate account of our research on human genetic differences with speculation that recent natural selection has led to worldwide differences in I.Q. test results, political institutions and economic development. We reject Wade’s implication that our findings substantiate his guesswork. They do not.
We are in full agreement that there is no support from the field of population genetics for Wade’s conjectures.
To those of us who’ve been complaining about Wade’s misappropriation of basic population genetics in support of his ideas about what people of different races may or may not be “adapted” to do, this is the equivalent of that scene from Annie Hall, except with more than a hundred Marshall McLuhans. Updated to add: The full list of 139 folks who signed the letter is posted here.
Sometimes, life is kinda like that. Hat tip to Jennifer Ouellette for the Science Insider story.
Updated to add: See also coverage by Nature, with some choice quotes from signatories; and by Jennifer Raff, who writes, “A strong blow has been dealt to scientific racism today.” Also, from Ed Yong:
Bicyclus anyana in its low-key natural look. Photo by Gilles San Martin, via Wikimedia Commons
Via NPR: a paper published online this week ahead of print at PNAS reports the results of an artificial selection experiment that changed butterflies’ wings from brown to blue.
We used artificial selection on a laboratory model butterfly, [Bicyclus] anynana, to evolve violet scales from UV brown scales and compared the mechanism of violet color production with that of two other Bicyclus species, Bicyclus sambulos and Bicyclus medontias, which have evolved violet/blue scales independently via natural selection.
Pangolins, or scaly anteaters, are delightfully weird. They have many of the adaptations we associate with anteaters—powerful front claws for breaking into anthills, a narrow snout for nosing into broken-open anthills, long tongues and sticky saliva for slurping up ants*—plus a sleek coat of overlapping scales. And, as you’ll see in this clip from the BBC’s The Life of Mammals, they’re (kind of) bipedal!
Pangolins are so different from other mammals, in fact, that all eight species are in a single genus Manis, which is the only genus in the family Manidae. As of this week the IUCN classifies every species in that family of weird adorable mammals as endangered, critically endangered, or vulnerable to extinction—because, apparently, they’re also pretty tasty.
As a review published in this week’s issue of Science describes in detail, we’re in the middle of the sixth mass extinction (that we know about) since life began on Earth, this one caused by the changes we’ve made to the planet. Pangolins are hardly going to be the only potential victims of that mass extinction—they’d be about 2% of the 322 terrestrial vertebrates estimated to have gone extinct since 1500.
(Sad hat-tip to Alex Wild.)
* Or termites, or other insects that hang out in burrows or rotting wood.