Thursday, August 29, 2013

Next lab meeting: something for everyone

Posted by Jessica Abbott

Female Drosophila melanogaster, photo by Qinyang Li.

Next week we'll have the first paper discussion of the fall.  I've chosen a paper that hopefully will have something for everyone, as it covers a number of different topics: biogeography, reproductive isolation, sex chromosome evolution, and fruit flies.

The paper: Tropics accelerate the evolution of hybrid male sterility in Drosophila

Abstract: Understanding the evolutionary mechanisms that facilitate speciation and explain global patterns of species diversity has remained a challenge for decades. The most general pattern of species biodiversity is the latitudinal gradient, whereby species richness increases toward the tropics. Although such a global pattern probably has a multitude of causes, recent attention has focused on the hypothesis that speciation and the evolution of reproductive isolation occur faster in the tropics. Here, I tested this prediction using a dataset on premating and postzygotic isolation between recently diverged Drosophila species. Results showed that while the evolution of premating isolation was not greater between tropical Drosophila relative to nontropical species, postzygotic isolation evolved faster in the tropics. In particular, hybrid male sterility was much greater among tropical Drosophila compared to nontropical species pairs of similar genetic age. Several testable explanations for the novel pattern are discussed, including greater role for sterility-inducing bacterial endosymbionts in the tropics and more intense sperm–sperm competition or sperm–egg sexual conflict in the tropics. The results imply that processes of speciation in the tropics may evolve at different rates or may even be somewhat different from those at higher latitudes.

Same time and place as usual, Tuesday the 3rd of September at 10:30 in Argumentet.