Temperature and hypoxia in ectothermic tetrapods

(1) Interactions between temperature and hypoxia in ectothermic tetrapods (reptiles and amphibians) are reviewed. (2) At temperature extremes, mismatches between oxygen demand and oxygen supply can lead to hypoxemia. Thresholds for both physiological and behavioral responses to hypoxia are elevated at high temperature and aerobic scope is reduced at both high and low temperature. (3) Environmental hypoxia is uncommon for most species in air, and for those living at altitude or in burrows, low metabolic rates and relatively low temperature probably prevents hypoxia from being a major problem. (4) For aquatic species, increasing temperature decreases both the aerobic dive limit and the relative importance of aquatic gas exchange to oxygen supply. (5) Tolerance to anoxic submergence is drastically reduced by increased temperature.