Meeting Abstract
Much recent theoretical and empirical work has sought to describe the physiological mechanisms underlying thermal tolerance in animals. Leading hypotheses can be summarized as either subcellular components (i.e. proteins or membranes) or organ systems (i.e. oxygen and capacity limited thermal tolerance) failing at high temperatures. Nonetheless, a general framework has remained elusive. We leverage decades of research on the physiology of ectothermic tetrapods, amphibians and non-avian reptiles, to address these hypotheses. Available data suggest both mechanisms are important. Thus, we propose an integrated framework, which we call Broad-sense Oxygen and Capacity Limited Thermal Tolerance (Broad-sense OCLTT). This framework explains how subcellular and organ system failures interact to limit performance and set tolerance limits at high temperatures. We further integrate this framework with the thermal performance curve paradigm commonly used to predict the effects of thermal environments on fitness. The Broad-sense OCLTT framework appears to successfully explain diverse observations in reptiles and amphibians and makes numerous predictions that remain untested. We hope that this framework spurs further research in diverse taxa and facilitates mechanistic forecasts of biological responses to climate change.
