Meeting Abstract
Introgression is increasingly recognized as a source of genetic diversity that fuels adaptation. Its role in the evolution of sex chromosomes, however, is not well known. Here we confirm the hypothesis that the Y chromosome in the ninespine stickleback, Pungitius pungitius, was established by introgression from the Amur stickleback, P. sinensis. Using whole genome resequencing, we identified a large region of Chr 12 in P. pungitius that is diverged between males and females. The region of differentiation falls within an inversion, which appears to prevent recombination between the chromosomes. Population genetic and phylogenetic analyses show that within this inversion, the Y chromosome of P. pungitius shares a most recent common ancestor not with the X chromosome, but with the homologous chromosome in P. sinensis. Our findings indicate that porous species boundaries can trigger rapid sex chromosome evolution.
