Adaptive introgression in an African malaria mosquito coincident with the increased usage of insecticide-treated bed nets

Significance We report that during a recent period of hybridization between two major African malaria mosquitoes, Anopheles gambiae and Anopheles coluzzii , an island of divergence on chromosome 2 introgressed from the A. gambiae into the A. coluzzii genome and its frequency subsequently increased. This introgression was coincident with the start of a major insecticide-treated bed net campaigns in Mali. These observations suggest that increased insecticide exposure acted as a selective force sufficient to drive introgression of an entire genomic island of divergence across the reproductive barrier separating these two species. This study provides a rare example of adaptive introgression in an animal species and elucidates the dynamics of how insecticide resistance evolved in A. coluzzii .