Résumé
Alleles subject to strong, recent positive selection will be swept towards fixation together with contiguous sections of the genome. Whether the genomic signatures of such selection will be readily detectable in outbred wild populations is unclear. In this study we employ haplotype diversity analysis to examine evidence for selective sweeps around knock down resistance (kdr) mutations associated with resistance to DDT and pyrethroid insecticides in the mosquito Anopheles gambiae. Both kdr mutations have significantly lower haplotype diversity than the wild type (non-resistant) allele, with kdr L1014F showing the most pronounced footprint of selection. We complement these data with a time series of collections showing that the L1014F allele has increased in frequency from 0.05 to 0.54 in 5 years, consistent with a maximum likelihood-fitted selection coefficient of 0.16 and a dominance coefficient of 0.25. Our data show that strong, recent positive selective events, such as those caused by insecticide resistance, can be identified in wild insect populations.