Major range loss predicted from lack of heat adaptability in an alpine Drosophila species

Climate warming is threatening biodiversity worldwide. Climate specialists such as alpine species are especially likely to be vulnerable. Adaptation by rapid evolution is the only long-term option for survival of many species, but the adaptive evolutionary potential of heat resistance has not been assessed in an alpine invertebrate. Here, we show that the alpine fly Drosophila nigrosparsa cannot readily adapt to heat stress. Heat-exposed flies from a regime with increased ambient temperature and a regime with increased temperature plus artificial selection for heat tolerance were less heat tolerant than the control group. Increased ambient temperature affected negatively both fitness and competitiveness. Ecological niche models predicted the loss of three quarters of the climatically habitable areas of this fly by the end of this century. Our findings suggest that, alongside with other climate specialists, species from mountainous regions are highly vulnerable to climate warming and unlikely to adapt through evolutionary genetic changes.