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Brad Seibel
Professor
University of South Florida, College of Marine Science
The evolution of oxygen supply and demand in animals
Abstract: An imbalance between oxygen supply and demand is thought to shape ecology, set thermal and biogeographical range limits and to constrain body size. Yet evidence for these theories is largely correlative. Missing from the conversation are the selective pressures shaping physiological oxygen supply and demand. Here, by analyzing metabolic traits in diverse species, I show that, regardless of size or temperature, the physiological capacity for oxygen supply has evolved to precisely supply the maximum evolved demand at the prevailing environmental oxygen pressure, regardless of temperatures and body size. I further report unique metabolic temperature sensitivities for the myriad of vertically-migrating oceanic species that daily cross depth-related gradients in temperature and oxygen. In these species, cold, rather than warm, waters currently constitute an energetic barrier to latitudinal range expansion. These findings imply that temperature mediates metabolism in response to ecological demands for activity, well beyond simple thermodynamic effects on biochemical reaction rates. They further suggests that oxygen supply does not set biogeographic limits or constrain body size.
Host: Professor Peter Girguis