Thermal physiology and species distribution models reveal climate vulnerability of temperate amphibians
ecological niche models, global climate change
Aim: High-latitude ectotherms are predicted to be less physiologically vulnerable to climate warming than tropical species based on their larger thermal safety margins, the distance between ambient temperatures and species' thermal optima. We sought to test the prediction that high latitude amphibians are buffered against the impacts of climate warming. Location: British Columbia, Canada. Methods: We estimated the risk from climate change for three high-latitude amphibian species (Spea intermontana, Rana aurora and Pseudacris regilla) by combining thermal performance experiments with species distribution models and predicted changes in maximum summer temperatures through the 2080s, in order to demonstrate temporal and geographical trends in vulnerability to climate warming among and within species. Results: We found that species have thermal safety margins of 3.2–3.8 °C based on current maximum summer temperatures. However, by the 2080s (emissions scenario A1B), we estimate that 45–82% of our focal species' current distributions will experience maximum summer temperatures above their thermal optima. We also found that by using long-term average temperatures, as some studies have done, there were almost no scenarios in which populations of any species were experiencing temperatures greater than their thermal optima. Main conclusions: Combining spatially explicit species distribution models with performance physiology allows us to predict where limiting temperatures will occur in the coming decades, and can guide climate mitigation and conservation efforts before populations decline. Despite moderate thermal safety margins, high-latitude ectotherms can be highly vulnerable to climate warming when spatio-temporal variation is incorporated into estimates of risk as a result of climate change.