Genomics of urban adaptation and exaptation in mosquitoes and consequences for vectorial capacity

As urbanization accelerates around the world, mosquitoes that are capable of surviving and thriving in urban habitats increasingly spread mosquito-borne diseases. Across the >3500 known species of mosquitoes, only a few rapidly adapted to the novel (on an evolutionary timescale) urban environments. In this review, we highlight several emerging themes and testable hypotheses from recent literature. First, apparent urban adaptations can be roughly divided into newer adaptations arising in an urban context and exaptations — traits that evolved in a different context, before modern urbanization. Second, variants involved in urban adaptation are often partitioned among species complexes and cryptic lineages, and the history of gene flow–selection balance may be related to the evolution of compact genomic architectures that could facilitate rapid urban adaptation. Third, urban adaptation often has consequences for vectorial capacity — the ability of mosquitoes to serve as effective vectors of a particular pathogen — though the selective drivers and genetic mechanisms underlying these differences are incompletely understood. To fully understand urban adaptation in mosquitoes, we advocate for a coordinated effort to increase linkages between evolutionary ecology, population genomics, and medical entomology research. We discuss the two traits for which all three perspectives are the most developed — host preference and insecticide resistance — before reviewing several other less studied traits.