Aedes aegypti vectors the pathogens that cause dengue, yellow fever, Zika virus, and chikungunya and is a serious threat to public health in tropical regions. Decades of work has illuminated many aspects of Ae. aegypti's biology and global population structure and has identified insecticide resistance genes; however, the size and repetitive nature of the Ae. aegypti genome have limited our ability to detect positive selection in this mosquito. Combining new whole genome sequences from Colombia with publicly available data from Africa and the Americas, we identify multiple strong candidate selective sweeps in Ae. aegypti, many of which overlap genes linked to or implicated in insecticide resistance. We examine the voltage-gated sodium channel gene in three American cohorts and find evidence for successive selective sweeps in Colombia. The most recent sweep encompasses an intermediate-frequency haplotype containing four candidate insecticide resistance mutations that are in near-perfect linkage disequilibrium (LD) with one another in the Colombian sample. It is possible that this haplotype may continue to rapidly increase in frequency and perhaps spread geographically in the coming years. However, we do observe an unusual pattern of LD within this region: although the insecticide resistance mutations them are in LD with one another, they are interspersed with stretches of polymorphisms that do not exhibit strong LD with any of the resistance mutations. This crenellated pattern of LD with the resistance mutations may suggest the presence of strong epistasis, undetected structural variation, or both—possibilities that we will examine in future work. Overall, our results extend our knowledge of how insecticide resistance has evolved in this species and add to a growing body of evidence suggesting that Ae. aegypti has an extensive genomic capacity to rapidly adapt to insecticide-based vector control.
Strong Positive Selection in Aedes aegypti and the Rapid Evolution of Insecticide Resistance
Abstract ID: 202
Event: The 3rd AsiaEvo Conference
Topic: Novel insights regarding genome architecture evolution in the arthropoda
Presenter Name: Daniel Schrider