Development partly determines the aerobic performance of adult deer mice, Peromyscus maniculatus.

Previous studies suggest that genetic factors and acclimation can account for differences in aerobic performance (V(O(2)max)) between high and low altitude populations of small mammals. However, it remains unclear to what extent development at different oxygen partial pressures (P(O(2))) can affect aerobic performance during adulthood. Here we compared the effects of development at contrasting altitudes versus effects of acclimation during adulthood on V(O(2)max). Two groups of deer mice were born and raised for 5 weeks at one of two altitudes (340 and 3800 m above sea level). Then, a subset of each group was acclimated to the opposite altitude for 8 weeks. We measured V(O(2)max) for each individual in hypoxia (P(O(2))=13.5 kPa, 14% O(2) at 3800 m) and normoxia (P(O(2))=20.4 kPa, 21% O(2) at 340 m) to control for P(O(2)) effects. At 5 weeks of age, high altitude born mice attained significantly higher V(O(2)max) than low altitude born mice (37.1% higher in hypoxia and 72.1% higher in normoxia). Subsequently, deer mice acclimated for 8 weeks to high altitude had significantly higher V(O(2)max) regardless of their birth site (21.0% and 72.9% difference in hypoxia and normoxia, respectively). A significant development x acclimation site interaction comparing V(O(2)max) in hypoxia and normoxia at 13 weeks of age suggests that acclimation effects depend on development altitude. Thus, reversible plasticity during adulthood cannot fully compensate for developmental effects on aerobic performance. We also found that differences in aerobic performance in previous studies may have been underestimated if animals from contrasting altitudes were measured at different P(O(2)).