Abstract
Modeling and cage experiments suggest that mosquito gene drive systems will enable malaria eradication, but establishing safety and efficacy requires field-testing in isolated populations. Documenting genetic isolation is notoriously difficult for species with vast polymorphic populations like the principal African malaria vector Anopheles gambiae. Using genome-wide variation, we assess Lake Victoria islands as candidate field-testing sites. One island, 30 kilometers offshore, is as differentiated from mainland samples as populations from across the continent, and we confirm isolation using adaptive variation as a powerful assay of connectivity. Collectively, our results suggest sufficient contemporary isolation of these islands to warrant consideration as field-testing locations.