Genomic evidence for convergent evolution of a key trait underlying divergence in island birds

Reproductive isolation can be initiated by changes in one or a few key traits that prevent random mating among individuals in a population. During the early stages of speciation, when isolation is often incomplete, there will be a heterogeneous pattern of differentiation across regions of the genome between diverging populations, with loci controlling these key traits appearing the most distinct as a result of strong diversifying selection. In this study, we used Illumina-sequenced ddRAD tags to identify genome-wide patterns of differentiation in three recently-diverged island populations of the Monarcha castaneiventris ycatcher of the Solomon Islands. Populations of this species have diverged in plumage color, and these differences in plumage color, in turn, are used in conspecific recognition and likely important in reproductive isolation. Previous candidate gene sequencing identified point mutations in MC1R and ASIP, both known pigmentation genes, to be associated with the difference...