Meeting Abstract
We show that the sister species of streamertail hummingbirds (Trochilus polytmus and T. scitulus) diverged recently and in situ on Jamaica, with their divergence likely facilitated by sexual selection during a period of geographic isolation. The pair form a stable hybrid zone where their ranges meet in eastern Jamaica. Geographic cline analyses support the hypothesis that this hybrid zone is maintained as a tension zone, in which selection against hybridization is offset by the dispersal of parentals into the zone. Streamertail hummingbirds are highly volant, yet bill color, the secondary sexual ornament that distinguishes the taxa, changes from ruby red (T. polytmus) to jet black (T. scitulus) over less than 5 km. A genome scan based on AFLP markers, three independently segregating autosomal loci, the hypervariable mitochondrial control region, six microsatellite markers, and over 6,000 high quality SNPs from a genotyping-by-sequencing dataset show little if any genetic differentiation between the taxa that would support the presence of post-mating reproductive isolating mechanisms. Instead, our data suggest rapidly evolved differences in bill color acts as a strong pre-mating deterrent to hybridization.
