Allochronic speciation with gene flow? Genomics of parallel breeding time divergence among storm-petrels (Hydrobatidae) Parallel evolution, in which similar phenotypes arise among independent lineages, provides strong insights into the mechanisms and constraints on evolution. However, whether the same genomic regions underly the evolution of parallel traits is often unclear. Storm-petrels (Procellariiformes: Hydrobatidae), a cosmopolitan family of island-breeding seabirds, provide a useful case study for parallel evolution. Several sister races of storm-petrels have independently diverged in breeding season – an example of parallel allochronic divergence. I am using low-coverage whole-genome sequencing to disentangle the origins of repeated breeding time switches in storm-petrels. I am examining allochronic sister races in the band-rumped storm-petrel species complex (Hydrobates spp.), as well as an allochronic species pair from Guadalupe Island, Mexico: Townsend’s (H. socorroensis) and Ainley’s storm-petrels (H. cheimomnestes). Firstly, I am using outlier analyses to determine whether the same genomic regions differentiate sympatric population pairs. Secondly, I am assessing the role of adaptive introgression in promoting parallel evolution and inspecting the overlaps between introgressed regions and genomic outliers. Preliminary results confirm that allochronic populations arose in parallel across the breeding range. Moreover, the identification of outliers and evidence for widespread introgression among seasonal populations suggest that gene flow may have facilitated parallel divergence in the storm-petrels. The use of annotated genome databases will complement these results by matching potential gene functions to the outliers, which will further improve our understanding of the drivers of population divergence and adaptation.
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