Population genomic analysis of isolation within the African malaria vector Anopheles melas

Anopheles (An.) melas (Diptera: Culicidae) is a major malaria vector throughout its distribution along the coast of West Africa where it breeds in brackish water. It is a member of the An. gambiae species complex, which is a model system for the study of speciation due to the recent radiation and genetic complexity of its member species. Understanding the genetic relationships between the isolated populations of An. melas has major implications for our understanding of its biology and control. Little information was known about the population genetic structure of An. melas until our recent study revealed species-level genetic differentiation between West, South, and Bioko Island populations. A maximum likelihood phylogenetic analysis found no support for the monophyly of An. melas population clusters when compared to other members of the An. gambiae species complex, suggesting that they diverged during, or soon after, the radiation of this complex. We used genome-wide SNP data from the three An. melas population clusters to perform population genomic analyses that provide a better understanding of the demographic history and evolution of the West, South, and Bioko Island An. melas population clusters. Using the An. gambiae genome as a reference, we identify regions of the genome that are receptive or intransigent to introgression, and those that show signatures of positive selection. We address how the demographic history of these populations has influenced their genome evolution, and how this information can be used to better understand the radiation of the An. gambiae species complex.