Phylogenomic analysis of the recently radiated sapsucker (Sphyrapicus) superspecies complex

Abstract

Sphyrapicus varius, S. ruber, and S. nuchalis are members of a closely related and recently radiated superspecies complex widely distributed throughout North America, with areas of range overlap and hybrid zones. I used genomic data to determine the evolutionary history of the three species. Three distinct genetic clusters corresponding to phenotypic species identification using both neutral and non-neutral genetic markers were identified along with possible candidate genes under selection. These genes may have played a role in adaptive evolution driving speciation. Additionally, I studied the genomic structure of a hybrid zone between S. varius and S. nuchalis. It was composed of advanced generation hybrids with lots of admixture within the zone, but no introgression of interspecific alleles outside of the contact zone. Within the zone, backcrosses differed along a north to south gradient, where southern individuals were more skewed to S. nuchalis ancestry and northern individuals to S. varius.