19/01/2015 - Brian Hollis - "Adaptation and antagonism in populations evolving without sexual selection"
University of Lausanne, Switzerland
Abstract: Sexual selection may accelerate adaptation, as "good genes" theory predicts, or act as a load upon populations because of conflict between the sexes. We investigate these possibilities with fly populations that have evolved in the laboratory for over 150 generations either with sexual selection (a polygamous mating system) or without sexual selection (a monogamous mating system). Monogamous populations benefit from the evolution of reduced sexually antagonistic interactions, which can be detected in the female post-mating transcriptional response. Male selection pressures are also greatly relaxed under monogamy. This has resulted in the evolution of feminized patterns of gene expression, suggesting strong constraints on sexually dimorphic gene expression in nature.
26/01/2015 - Wolfgang Stephan - Population genomics of adaptation in Drosophila melanogaster
Abstract: In several organisms (whose genome has been sequenced) scans of DNA sequence variation have been carried out to elucidate the recent demographic and adaptive histories of these species. Using selective sweeps, it is possible to identify adaptive events in the genome. I will present results from our work on Drosophila melanogaster. I show that selective sweep analysis can be used to accurately map targets of positive selection in the genome. Furthermore, I will discuss whether selective sweep mapping can be combined with QTL mapping to determine the phenotype selection has been operating on. Two case studies will be highlighted: (1) the divergence of the tandemly duplicated polyhomeotic (ph) genes under positive selection, and (2) the localization of candidate genes for cold tolerance.