EEB events: Thursday seminar: The genomic basis of parallel evolution and reproductive isolation in sticklebacks: Dr. Felicity Jones, Stanford University
Felicity Jones, Postdoctoral Researcher, Department of Developmental Biology, Stanford University
Ecological speciation is the consequence of reproductive isolation arising from divergent adaptation to different ecological niches. The parallel evolution of stickleback species-pairs provides an excellent opportunity to identify the environmental and molecular mechanisms that influence this evolutionary process. Through laboratory and field studies of hybrid zones between marine-freshwater species-pairs, I have studied potential pre- and postmating reproductive barriers and found postzygotic environmentally-dependent genetic effects leading to reduced overwinter survival of hybrids to be a major factor. However, the underlying genetic loci, genomic mechanisms, their phenotypic and fitness effects, and the environmental context in which they act remains poorly understood.
We have developed a genomic screen in order to catalog the genetic loci underlying repeated marine-freshwater adaptation. We selected 21 sticklebacks for short-read whole genome sequencing. Our analysis of the signatures of parallel adaptation in these marine-freshwater species-pairs identified 42 loci with extremely high resolution that are distributed throughout the genome. Our study highlights the importance of chromosomal inversions, reduced recombination, and the reuse of globally shared standing genetic variation in driving repeated evolution of marine and freshwater sticklebacks and maintenance of reproductive isolation. I will discuss how adaptation of sticklebacks to new freshwater environments may involve dynamic reassemblies of multiple distinct loci, and the relative importance of coding vs. regulatory changes in this classic example of repeated adaptive evolution in nature. This genomic information can improve our understanding of ecological speciation by providing an excellent footing for identification and functional testing of the environmental context and fitness effects of mutations. This will be complemented by ongoing genomic dissections of additional species pairs along a gradient of reproductive isolation towards ecological speciation.
Coffee and cookies will be served at 4 p.m.
Host: Professor Patricia Wittkopp
Location: 1210 Chemistry