Tuesday, June 16, 2009

Evolution2009: Finale

I started Monday morning with a really ingenious talk by Robert Thomson of UC Davis. The title of his talk was "Rapid Progress on the Vertebrate Tree of Life," which, though accurate, barely describes what he did. Basically, he downloaded all the vertebrate sequences from GenBank and assembled a ginormous supermatrix. Then, he divided it up by year, so that he had supermatrices corresponding to all the sequences available in GenBank in 1993, 1994, 1995, up to 2008. Now we all know that GenBank has undergone an exponential growth since it's beginning, and he showed a graph showing a similar trend in phylogeny publications. So it stands to reason that our ability to resolve nodes in the vertebrate tree of life must also have increased over the same stretch of time. And voila, sure enough, his results confirmed that the number of resolved nodes goes up right along with the sequence content and number of phylogeny papers. I really like those "big picture" kind of projects. That was a great way to start the day.

The next talk I have notes on is Daniel Rabosky's "Alternative paradigms to explain rapid diversification during evolutionary radiations." I remember enjoying the talk, but my notes are indecipherable. I should have written it up yesterday when it was still fresh. Oh well, I understand he has a paper coming on this subject, so I'll look forward to reading it. The basic gist was the idea that radiations might not be radiations into a bunch of empty niches but that new species originate only after old species go extinct. I wish I could give a better summary, but I'll have to wait for the paper.

The rest of Monday and most of Tuesday I spent listening to talks on phylogenies or systematics. Nothing really jumped out at me. Some were pretty cool, like Heather Lerner's talk on the Hawaiian honeycreepers. For those not in the know, the honeycreepers (Drepanidinae) are a set of bird species that are a classic example of adaptive radiation. As such, their phylogeny is difficult to resolve (because they radiated - see?). So she's got this project where she's sequencing about 8500 nucleotides of nuclear markers and the full mitochondrial genomes (about 16 kb) for the honeycreepers. She's not done yet, but she's got good support for a number of branches on the tree.

I did go listen to Cracraft, and he was pretty good. He made some very interesting points about our ability to actually explain things with evolutionary hypotheses or whether we're just handwaving about correlations. I usually choose the talks I go to by my interest in the topic rather than just the speaker. But I figured this time, what the heck, I'd go hear someone I've actually heard of before. As I expected, the room was pretty full for his talk, then about half the people got up and left as soon as it was over. I felt bad for the folks who had to follow him. Especially when they were trying to come up with explanations that they admitted facetiously were probably just correlations.

The final talk that intrigued me was Marco Archetti's "Evidence for the maintenance of autumn colors by coevolution." He argued that the color of leaves in the fall, particularly the red leaves, were actually adaptive rather than just a by-product of leaf senescence. What I liked about the talk was how he structured his argument. I guess maybe I was just burned out on simulations, coalescents, and controlled experiments by that point. I don't know why, but his talk really reminded me of the way Darwin structured his arguments in Origin. For example, he showed that aphids don't congregate on things that are red colored, and then he showed that species of trees that have red leaves in the fall are much more susceptible to aphid-born bacterial disease than close relatives that don't turn red in the fall. Ergo, it stands to reason that the red leaves are a kind of adaptation to keep the aphids away. I don't know if he's right, but doesn't that sound like something Darwin would argue?

So that's it for this conference. As I said, it was enjoyable as usual. Next year's conference is in Portland, and I'll probably go, God willing.