Ontogenesis of evolved changes in respiratory physiology in deer mice native to high altitude.

High-altitude environments are cold and hypoxic, and many high-altitude natives have evolved changes in respiratory physiology that improve O uptake in hypoxia as adults. Altricial mammals undergo a dramatic metabolic transition from ectothermy to endothermy in early post-natal life, which may influence the ontogenetic development of respiratory traits at high altitude. We examined the developmental changes in respiratory and haematological traits in deer mice () native to high altitude, comparing the respiratory responses to progressive hypoxia between highland and lowland deer mice.