#OccupyAmazon by occupying real bookstores

Uncle Hugo’s, where it is entirely possible to trip over a stack of Asimov novels and break a model of the ship from Lost in Space if you’re not careful. Photo by Olivander.

You may have heard that Amazon.com took its competition with brick-and-mortar booksellers to a new level this holiday season, offering a discount to people who go into a store and scan a product with Amazon’s smartphone app to find out what price Amazon was offering for the same wares (presumably cheaper, and free of local sales tax). If you’re not sure why this is an asshole move on the part of the gargantuan online retailer, you’ve got a good one in this op-ed by Richard Russo, who talks to a number of other authors, all of whom have done pretty well thanks to sales via Amazon, about the whole business. Money quote from Ann Patchett:

“… If you like seeing the people in your community employed, if you think your city needs a tax base, if you want to buy books from a person who reads, don’t use Amazon.”

I bought a lot of books as gifts this holiday season, and I’m glad to say I bought none of them from Amazon. Instead, I went to the collegiate used bookstore the Book House, the “indie behemoth” Magers & Quinn, and the astounding nerdcave that is Uncle Hugo’s. I probably paid a bit more, and I’ll have to figure out how to fit all the books in my carry-on instead of shipping them ahead of me, but I had a lot more fun doing the shopping, too. ◼

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Frightened birds make bad parents

Song sparrow chicks. Photo by Tobyotter.

ResearchBlogging.orgPredators have an obvious impact on their prey: eating them. But if the threat of predators prompts prey species to change their behavior, those behavioral changes can also affect prey population dynamics [$a]—and thereby, potentially, the prey’s evolution—even if the predators never actually catch any prey.

This is the effect documented in a short, sharp study just published in Science, in which Liana Y. Zanette and her coauthors show that song sparrows raise fewer chicks if they simply think that there are predators nearby [$a].

The team’s experimental design was simple but probably pretty work-intensive. Over the course of one summer on several small islands off the coast of British Columbia, they watched song sparrows choose mates and build nests. Once nests were established, the team surrounded them with anti-predator defenses: netting and electrified fences. They confirmed that these measures kept predators out with regular video surveillance. And then they turned on the loudspeakers.

At some nests, the team broadcast looped recordings of calls made by song sparrow predators—raccoons, crows and ravens, hawks, owls, and cowbirds. At control nests, the broadcast was instead a playlist of similar-sounding calls made by non-predators, including seals, geese, hummingbirds, and loons. The team then monitored the nests, recording the behavior of the mated pair at each nest, and the ultimate success of the eggs they laid.

An adult song sparrow, looking watchful. Photo by kenschneiderusa.

The results are pretty unambiguous. Pairs of song sparrows that heard predator calls laid fewer eggs than pairs that heard non-predators. Of the eggs laid by pairs who heard predator calls, fewer hatched, and of those hatched chicks, fewer survived fledge. Just the continuous, threat of predators—predators that were never visible—reduced the number of chicks the sparrows fledged.

The reasons for the reduced offspring are apparent from other behavioral observations. Birds in the predator-call treatment were perpetually on high alert, as measured by “flight initiation distance,” the distance up to which a researcher could approach the nest before the birds took flight. Sparrows in the non-predator treatment let researchers get about 120 meters from the nest before taking off; sparrows in the predator treatment wouldn’t tolerate humans within twice that distance. In the predator treatment, sparrows spent less time sitting on their eggs, and visited to feed their chicks less frequently. Not surprisingly, chicks in the predator treatment also gained less weight than chicks in the non-predator treatment.

And, in what may be the most poignant data set I’ve ever seen in print, the team also measured the skin temperature of chicks in each nest 10 minutes after the parents had left. Chicks in the predator-call treatment were measurably, and significantly, colder.

So the simple fear of predators is enough to prompt free-living song sparrows to lay fewer eggs, and raise fewer of the eggs they do lay to fledging. However, the absolute difference in offspring between sparrow pairs in the predator and non-predator treatments—40%—probably reflects the maximum effect we might expect to see in natural populations.

That’s because left to themselves, sparrows probably seek nesting spots with less predator activity. Here, all the sparrows had established nests in what, presumably, were the best spots they could find—but for half of them, the new neighborhood suddenly seemed to become a lot less safe shortly after they settled in. What Zanette et al. document is very much a behavioral, short-term response, and it’s one that many prey animals may be able to mitigate, or avoid altogether, with other behavioral responses. It’s hard to say how exactly it reflects the impact that fear of predators might have in sparrow populations unmolested by ornithologists.

Nevertheless, this result does suggest that for many prey animals, the fear of predators can, itself, be something to fear. ◼

References

Creel, S., & Christianson, D. (2008). Relationships between direct predation and risk effects. Trends in Ecology & Evolution, 23 (4), 194-201 DOI: 10.1016/j.tree.2007.12.004

Martin, T. (2011). The cost of fear. Science, 334 (6061), 1353-4 DOI: 10.1126/science.1216109

Zanette, L., White, A., Allen, M., & Clinchy, M. (2011). Perceived predation risk reduces the number of offspring songbirds produce per year. Science, 334 (6061), 1398-1401 DOI: 10.1126/science.1210908

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Holiday baking

Grandma’s date pudding. Photo by jby.

I could frankly do without a lot of holiday-time rituals, but I’m perfectly happy to have the excuse for baking. This year I made cranberry orange bread for the folks in my lab, following a great recipe in Mark Bittman’s magisterial How to Cook Everything. I’ve also taken a crack at Ma Savage’s Christmas Snowballs for one party, and for the departmental party, I dug up a family tradition: Grandma Bender’s date pudding.

My mom’s mom has a pretty serious sweet tooth, and so I learned to love this recipe—cubes of rich, sweet, date cake layered in sweetened whipped cream—as part of the main course for Thanksgiving and Christmas dinners. Nowadays, I cut the sugar from the whipped cream, and it still goes over quite well as a dessert. It’s also possible to substitute in whole wheat or spelt flour, which only makes the cake denser and richer. Recipe follows:

Preheat the oven to 350°F. Heat one cup of water to boiling, and soak one cup of chopped dried dates in the hot water for 20 minutes. Cream together one tablespoon of butter and one cup of sugar, and then blend in one egg, one cup of flour, one cup of chopped pecans (or other nuts), half a teaspoon of salt, one teaspoon of baking soda, and one teaspoon of vanilla extract. Finally, fold in the soaked dates and any liquid remaining with them; blend it all well. Spread this batter in a greased 9 inch by 13 inch cake pan and bake it for 25 minutes, or until a toothpick inserted in the middle of the cake comes out clean.

When the cake is done, let it cool to room temperature, or stick it in the fridge or freezer if you’ve baked it in advance, which is often convenient. When you’re ready to assemble the pudding, whip two cups of heavy cream together with a teaspoon or two of vanilla extract until it’s stiff, then cut the cake into one-inch cubes and layer cubes of cake with the whipped cream in a midsize serving bowl. ◼

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Science online, ancestral penis reconstruction edition

You want to dissect my what?! Photo by GAC’63.

Video of the week, via Open Culture: Robert Krulwich describes behavioral experiments that dissected how ants navigate. (You may remember this as the subject of one of Jason Goldman’s earliest posts.)


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Can’t keep us apart: Brood parasitic birds have specialized on the same hosts for millions of years

A male greater honeyguide. Photo via Safari Ecology.

ResearchBlogging.orgBrood parasitic birds lay their eggs in other birds’ nests, a lazy approach to parenting that shapes the behavior and evolution of brood parasites in all sorts of interesting ways.

Brood parasite chicks often kill their adoptive nestmates, and can grow up confused about their species identity. To better trick their hosts into accepting “donated” eggs, many brood parasites have evolved eggs that mimic the hosts’—and some hosts have evolved contrasting eggs in response. A recent genetic study now shows an even subtler pattern arising from this host-parasite coevolutionary chase: lines of parasitic females that have specialized on the same host species for millions of years.

The brood parasite in question is the greater honeyguide, an African bird best known for helping people find bee colonies (though the story that honeyguides also guide honey badgers don’t have much factual basis). However, honeyguide females also lay their eggs in the nests of several host species—including hoopoes, greater scimitarbills, green woodhoopoes, little bee-eaters, and striped kingfishers. Although the honeyguides’ eggs aren’t colored like their hosts’, they do have matching shapes—the hosts all nest in tree cavities, where lighting is too poor to notice a mis-colored egg, but an oversized or oddly shaped one would stand out.

A hoopoe, one of the birds that “adopts” greater honeyguide eggs. Photo by Hiyashi Haka.

There’s an evolutionary catch, though: hoopoes, scimitarbills, and woodhoopoes lay oblong eggs, while the bee-eaters and kingfishers lay spherical eggs. Yet honeyguide females manage to lay eggs of matching shape and size in the nest of each host. Individual brood parasites can’t adjust the shapes of their eggs to match those in a host nest—they find hosts with eggs that will match their own.

How do they do it? Maybe each female honeyguide actually goes looking for nests like the one she grew up in, either because she is compelled to by some genetic instinct, or because she learns to recognize a potential host in the course of being raised by that host. Or maybe the host birds are so good at recognizing and rejecting oddly-shaped parasite eggs that only well-matched eggs make it to adulthood. Any of these processes could result in long lineages of female honeyguides laying eggs in the nests of the same host species their mothers, grandmothers, and great-grandmothers used. This is precisely the pattern Claire Spottiswoode and her coauthors found in the population genetics of greater honeyguides.

Spottiswoode et al. collected genetic data from honeyguides using all five of the host species mentioned above, and compared the patterns of relatedness from different genetic markers to patterns of host use. The pattern of differentiation in a marker from the mitochondrial genome—genes contained in the mitochondria, which mothers pass on to their offspring but fathers do not—neatly divides the honeyguides between hosts with oblong eggs and the hosts with spherical eggs. By applying a molecular clock to the mitochondrial data, the team found that the division between oblong-egg and spherical-egg honeyguides dates back as long as 3 million years ago. So honeyguide females have been tracking the same hosts, or very similar ones, for quite some time!

However, no such pattern is evident in four genetic markers from the nuclear genome, which is inherited via both parents. That suggests male honeyguides don’t discriminate among females based on host fidelity—mates pair off regardless of what host species they each grew up with. Spottiswoode et al. also note that this result hints at how honeyguide egg characteristics and host preferences could be inherited: via the female sex chromosome. In birds, biological sex is determined by the Z and W chromosomes—individuals with two Z chromosomes develop as males, and individuals with a Z and a W chromosome develop as females. Host preferences and egg shape inherited via the W chromosome would then be carried only by females.

However, the data presented here don’t directly test the W-chromosome hypothesis. That would require markers—or better yet complete sequence data—from the W chromosome itself, and (to be really thorough) lots more markers from the rest of the nuclear genome as well. That’s a lot of genetic data to collect, but we are very close to the day when such data are easily collectible. ◼

Reference

Spottiswoode, C., Stryjewski, K., Quader, S., Colebrook-Robjent, J., & Sorenson, M. (2011). Ancient host specificity within a single species of brood parasitic bird. Proc. Nat. Acad. Sciences USA, 108 (43), 17738-42 DOI: 10.1073/pnas.1109630108

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Open Lab 2011 finalists: I’m in a book (again)!

I’ve already tweeted about this last night, as soon as I got the e-mail—but Jennifer Ouellette has just made it official with the complete list of science blog posts chosen for Open Lab 2011. And among them is my long discussion of natural selection and homosexuality. It’ll be great to see that piece in actual dead-tree print. It’ll be even better to see it alongside top-notch writing from such a long list of folks whose work I admire. ◼

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Nothing in Biology Makes Sense: Tracing the evolutionary history of HIV infection

The molecular structure of HIV. Photo by PHYLOMON!.

In the latest post at the group blog Nothing in Biology Makes Sense!, contributor Luke Swenson describes how biologists can reconstruct the evolutionary history of HIV to estimate when the virus make the jump from chimps to humans, or even when a single patient became infected.

Although HIV evolves rapidly, it does so at a fairly constant rate. In essense, you can use this constant rate to act like a clock to tell you roughly how many changes accumulate over a year. Then, by figuring out the number of changes it would take for both sequences to converge on a single identical sequence (their most recent common ancestor, “MRCA”), you can get an estimate of the date that the MRCA existed at.

This is one of the best cases I know about in which evolution directly informs medical practice and treatment, and it’s well worth reading the whole thing. ◼

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Diversity in Science Carnival No. 11: Native American Heritage Month edition

There’s a new edition of the Diversity in Science blog carnival out today, too: Urban Scientist DNLee rounds up stories of Native Americans in science, technology, engineering, and mathematics disciplines for Native American Heritage Month. It includes meditations on the value of cultural diversity in science, celebrations of individual scientists, and discussion of scientific insights from Native cultures that we’re still just beginning to recognize. ◼

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Carnival of Evolution, December 2011: A very special carnival of evolution

Forty-two. Photo by Valerian Gaudeau.

The new Carnival of Evolution, freshly posted over at the Ocelloid, is the forty-second iteration of the monthly roundup of online writing about evolution, the universe, and everything. Well, maybe not everything.

Highlights include, but are not limited to, Larry Moran illustrating the difference between census population size and effective population size, Hannah Waters on the evolutionary context of grieving, and Jenna Gallie’s description of her own research on rapid adaptive evolution by E. coli. There are also multiple contributions from Nothing in Biology Makes Sense!, in case you haven’t already seen them. Go read the whole thing, and don’t forget your towel. ◼

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Science online, gesturing ravens edition

Raven in flight. Photo by ingridtaylar.

And lastly, here’s video of a starfish-inspired “boneless” robot in action. Good luck getting to sleep tonight!


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