Wednesday, August 26, 2009
Second conference day: Agents of selection and the ecology of selection
The second full conference day in Turin has been spent in the symposium that I organized (together with Alexis Chaine) entitled The phenotype-fitness map revisited: agents of selection and the importance of ecology in evolutionary studies. This symposium was, I would say, a HUGE success, and the room was crowded from the very beginning. It is clear to me that evolutionary biologists are increasingly realizing that they should not take ecology as "given" or treat it as a "black box" and only focus on DNA-sequence variation, which has been dominating these evolutionary conferences a lot the past decade.
Luckily, things are now changing and there is an increasing interest in the actual ecological causes of selection and their effects of evolutionary diversification. These ecological factors include inter- and intraspecific competition, predation, parasitism, social environments, to name only a few. Todays speakers included Craig Benkman, who gave an interesting overview of the crossbill radiation in North American Europe (see picture above!) and its ecological causes: the size and hardness of the cones of coniferous trees. Benkman showed that selection on cones by crossbills changes if there are also squirrels present in the area, a nice example of how interspecific competition can have a dramatic effect on evolutionary trajectories.
The other invited speaker was Stevan J. Arnold, a legendary evolutionary biologist and quantitative geneticist, who developed the statistical framework of estimating selection gradients in natural popualtions (together with Russel Lande). It was therefore very nice to see both Steve Arnold and Russ Lande sitting on the front row of this symposium, enjoying the fact that their landmark paper from 1983 (published in Evolution) still inspires workers today. Few papers in evolutionary biology has been cited as much as this landmark one.
Steve Arnold gave a talk about how the adaptive landscape model of microevolution can be extended to the macroevolutionary scale to understand phenomena like adaptive radiations. He presented some new models and a newly developed software (MIPoD: Microevolutionary Inference from Patterns of Divergence) that can estimate parameters like the strength of long-term stabilizing selection and its relationship to genetic drift and other evolutionary forces, using phylogenetic data, estimates of effective population sizes and phenotypic and genetic information from different evolving populations. He illustrated this new approach using his own collected empirical data on the number of vertebrae in gartern snake populations from different parts of North America.
Now, I will go and have a beer with my close college Tom van Doorn to prepare for tomorrow, which will include a trip to Mont Blanc in the afternoon. Hopefully, we will see some nice Alpine birds!