UC EVENTS

Testing the oxygen-temperature hypothesis of polar gigantism Ectotherms in polar seas are often larger than their warm-water relatives, a pattern known as ‘polar gigantism.’ Although polar gigantism has been ascribed to a variety of mechanisms, one idea—the oxygen-temperature hypothesis—has received significant attention in the past twenty years. It proposes that low polar temperatures depress metabolic demand for oxygen more than they depress supplies of oxygen to tissues, and that this shift releases polar organisms from oxygen-based constraints on body size. In this talk, I review conflicting evidence bearing on the hypothesis. In addition, I propose that the conflicts can be resolved by revising the oxygen-temperature hypothesis to account for short- versus long-term challenges to oxygen homeostasis. The revised hypothesis focuses on attention on the energetic costs of oxygen homeostasis and suggests that polar warming will disproportionately affect the largest-bodied species.