Physiological Stresses Under Climate Change Drive Range Shifts in Small Ectotherms

ABSTRACT Aim Climate change is expected to impose severe physiological stress on ectotherms, potentially reshaping their geographic distributions. Many species are expected to be impacted by the detrimental effects of climate change on their homeostatic balance, with suitable habitat shifting to higher latitudes and elevations. However, little is known about the ecophysiological mechanisms driving their redistribution and the extent to which their geographic range might be altered. Location Australia. Time Period Present and future. Major Taxa Studied Lampropholis skinks. Methods We assessed the impacts of future climate change scenarios on Lampropholis skinks by integrating physiological data with biophysical and species distribution models. By simulating skinks physiology and behaviour across Australia, we compared the physiological stresses they face currently to those predicted for future climatic scenarios (+2°C and +4°C). We also evaluated whether their geographic range will shrink or expand with climate change using mechanistic species distribution modelling. Results We found that all species will experience increased dehydration, higher metabolic costs and prolonged exposure to critical thermal limits under climate change scenarios across their distribution. These physiological constraints will reduce activity time and drive range contractions, where suitable habitats could shrink by half. Most species are predicted to shift to higher latitudes in search of more suitable habitats. Main Conclusions Our findings provide evidence that physiological stresses will cause shifts in ectotherms' ranges towards higher latitudes, and their ranges may shrink or collapse. Even widespread generalist species, often considered more resilient to climatic variations, are projected to experience significant physiological stress under future climate scenarios. Our study underscores the vulnerability of both specialist and generalist ectotherms to climate change, with important implications for biodiversity conservation.