Meeting Abstract

120-1  Sunday, Jan. 7 08:00 – 08:15  A Direct Test of the Aerobic Capacity Model for the Evolution of Endothermy MCKENNA, AJ*; SANTAMARIA, J; VAN BRUEKELEN, F; Univ. of Nevada, Las Vegas; Univ. of Nevada, Las Vegas; Univ. of Nevada, Las Vegas austin.mckenna@unlv.edu

A definition of endothermy may be an increase in metabolism which leads to increased body temperatures. Basoendothermic mammals like afrotherians, marsupials, and monotremes maintain lower and more variable body temperatures. Some hypothesize that the evolution of increased endothermy/homeothermy was to allow increased exercise performance. The hypothesis centered on an increased ability to run longer or faster when body temperature was higher. Common tenrecs (Tenrec ecaudatus) have extremely variable body temperatures. Animals housed at 12 °C are able to run or swim when body temperature = ~14 °C. We swam tenrecs while monitoring oxygen consumption at ambient/body temperatures at 16, 20, 24, 28, and 32 °C. We calculated the maximal rate of oxygen consumption (Vo_2max) at the different temperatures. Vo_2max was decreased at lower body temperatures. Endurance (time at 80% of Vo_2max) did not change across temperature. We suspect that selection for speed and Vo_2max may have contributed to the ability to perform endothermy. However, not all indices of performance are affected equally by temperature.