1. The vulnerability of species to climate change is jointly influenced by geographic phenotypic variation, acclimation, and behavioral thermoregulation. The importance of interactions between these factors, however, remains poorly understood. 2. We demonstrate how advances in mechanistic niche modelling can be used to integrate and assess the influence of these sources of uncertainty in forecasts of climate change impacts. 3. We explored geographic variation in thermal tolerance (i.e. maximum and minimum thermal limits) and its...