Print PageEvolutionary history and physiology mediate species responses to environmental change. For example, recent studies have shown high vulnerability to global warming for tropical species that do not naturally experience the high variability in temperature seen at higher latitudes. However, the extent to which spatial heterogeneity in the environment may affect tolerance and therefore climate change impacts remains unknown. In this study, we statistically evaluated the importance of large scale spatial heterogeneity on warming tolerance for insect species globally and subsequently used that statistical relationship to model future impacts of climate change on fitness.
Results/Conclusions
Our results show significant effects of spatial heterogeneity in temperature on warming tolerance (defined here as the difference between critical thermal maximum and current temperatures) as well as thermal safety margins (the thermal distance between optimum and current temperatures) in insects. Specifically, in environments where the intra-annual standard deviation in temperature is comparable to spatial standard deviation in temperature (low seasonality environments - at about or below 4° C), spatial heterogeneity correlates strongly and positively with warming tolerance. Furthermore, based on this relationship, we find that global climate change projections of direct physiological impacts on insect fitness highlight the vulnerability of tropical lowlands and spatially homogenous areas to future warming. While temporal variation in temperature, i.e. seasonality, remains the best predictor for ectotherm warming tolerance, spatial thermal heterogeneity may play a critical role in ectotherm climatic adaptation particularly in low seasonality tropical environments.
