Evolved increases in running performance in cold hypoxia in high-altitude deer mice

The cold and hypoxic conditions at high altitude can challenge the ability of small endotherms to meet the high energy demands of locomotion and thermoregulation. We examined how high-altitude natives overcome this challenge through plastic and/or evolved improvements in locomotory performance. Deer mice (Peromyscus maniculatus) native to high- and low-altitude were each born and raised in captivity, then acclimated to warm normoxia or cold hypoxia as adults. Running endurance was then measured