The genetic basis of saltwater tolerance in mosquitoes

Parallel adaptation to saltwater has occurred repeatedly in Anopheline mosquitoes. Indeed, in the Afrotropical Anopheles gambiae complex alone this trait has evolved at least twice allowing these mosquitoes to exploit coastal habitats, which has resulted in increased malaria transmission in these areas. Despite the discovery of this phenotype more than 50 years ago and its importance to public health, nothing is known about the genes that control it. Here, we extensively characterize the phenotypic difference between the saltwater tolerant species Anopheles merus and the freshwater species Anopheles gambiae. We discovered that penetrance of this phenotype is strongly developmentally dependent and identified a saline dose that could discriminate between the two species allowing Quantitative Trait Locus (QTL) Mapping. Using high-throughput multiplex shotgun genotyping (MSG) we mapped the genomic regions underlying this trait and identified a handful of high-priority candidate genes.