Evolutionary adaptation under climate change: Aedes sp. demonstrates potential to adapt to warming

Climate warming is expected to shift the distributions of mosquitoes and mosquito-borne diseases, facilitating expansions at cool range edges and contractions at warm range edges. However, whether mosquito populations could maintain their warm edges through evolutionary adaptation remains unknown. Here, we investigate the potential for thermal adaptation in Aedes sierrensis, a congener of the major disease vector species that experiences large thermal gradients in its native range, by assaying tolerance to prolonged and acute heat exposure, and its genetic basis in a diverse, field-derived population. We found pervasive evidence of heritable genetic variation in acute heat tolerance, which phenotypically trades off with tolerance to prolonged heat exposure. A simple evolutionary model based on our data shows that the estimated maximum rate of evolutionary adaptation in mosquito heat tolerance typically exceeds that of projected climate warming under idealized conditions. Our findings indicate that natural mosquito populations may have the potential to track projected warming via genetic adaptation. Prior climate-based projections may thus underestimate the range of mosquito and mosquito-borne disease distributions under future climate conditions. Significance StatementGlobal change may have profound impacts on the distribution of mosquito-borne diseases, which collectively cause nearly one million deaths each year. Accurately predicting these impacts is critical for disease control preparedness, and will depend, in part, on whether mosquitoes can adapt to warming--a key open question. Using experimental and genomic data from a relative of major vector species that already experiences a wide thermal gradient, we find that natural mosquito populations have high levels of genetically-based variation in heat tolerance that could enable adaptation on pace with warming. Incorporating the potential for adaptive responses may therefore be necessary for accurate predictions of mosquito-borne disease distributions under warming, which is critical for preparing mosquito control interventions.