Fig. 3. Top panel, aerobic performance at 13 weeks of age measured in hypoxia and normoxia. Mice were pooled by acclimation altitude because this was the only significant main effect (see Results). Asterisks represent statistical significance within acclimation altitude; lower-case letters represent statistical significance in hypoxia and upper-case letters represent statistical significance in normoxia. Means are body mass-corrected values from ANCOVA and error bars are s.e.m. Bottom panels, adjusted means ± s.e.m. from ANCOVAs performed separately for trials in hypoxia (left) and normoxia (right). The birth site x acclimation altitude interaction was significant in both ANCOVAs (see Results).