| This study examined the rangewide genetic structure of three hybridizing woodpecker species (Sphyrapicus ruber, S. nuchalis, and S. varius), and hybridization at a S. nuchalis/S. varius hybrid zone in central Alberta. Mitochondrial DNA and nuclear Z-linked markers show high intraspecific population connectivity, and limited interspecific connectivity predominantly occurring in hybrid zones. We found evidence of a Haida Gwaii refugium for S. ruber and an east-west Pleistocene split for S. varius. Genetic data and Ecological Niche Modelling suggest these species diverged, not allopatrically as has long been assumed, but in sympatry with gene flow. Next-generation sequencing methods and traditional SNP analysis showed a well-established S. nuchalis/S. varius hybrid zone, with high rates of introgression, particularly in S. nuchalis. While hybridization in contact zones is extensive, movement of alleles out of the hybrid zone is limited. As such, plumage, behaviour, or ecology might also impact sapsucker speciation. |
