Texas A&M University
Swedish University of Agricultural Sciences
Host: Molly Przeworski
Title: The genetic basis for adaptive evolution in Atlantic herring revealed by whole genome sequencing
Abstract: The possibility to assemble any genome and resequence multiple individuals from the same species has radically changed the field of evolutionary biology. In this presentation I will present how we have used whole genome sequencing to study the genetic basis of ecological adaptation the Atlantic herring (Clupea harengus), which is one of the most abundant (census population size about 1012). Earlier studies based on a limited number of genetic markers (isozymes and microsatellites) had hardly revealed any genetic differentiation at all between populations living in strikingly different environments, such as the Atlantic Ocean and the brackish Baltic Sea, or spawning on different times of the year (early spring to late fall). How is this possible? Whole genome sequencing of multiple populations and individuals has now revealed that the FST distribution in this species deviates significantly from the one expected under selective neutrality with the great majority of loci showing no genetic differentiation while a small percentage show highly significant differentiation. This makes this species a model organism for detecting signatures of natural selection. These studies revealed a new enigma namely that the Atlantic herring has only a moderate nucleotide diversity (π=0.3%), “only” three-fold higher than humans, despite a huge census population size.