Effect of altitude on endurance running of Peromyscus maniculatus

Abstract

One subspecies of deer mouse is distributed from the floor of Death Valley to the tops of California's highest peaks. Endurance studies were made on two populations from 4,000 and 12,470 ft, respectively, at the Owens Valley and Barcroft Laboratories of the White Mountain Research Station. Mice ran on a treadmill at a speed of 40 m/min and an inclination of 50 % (22.5 deg). Studies were made in February and March, so all animals used were adults. The mean of 25 performances by valley mice was 15.8 min; the mean of 22 performances by mountain mice was 7.5 min. The chief factor of difference between the two groups is in the reduced pO₂ of the mountain environment and consequent hypoxia at this altitude. However, customary ambient temperatures are quite different, although room temperatures in which the animals were kept were similar. Although there is a possible differential effect of the same ambient temperature on the two mice populations, it was not discernible within each population except possibly in those trials run at over 20 C. Submitted on August 11, 1960