Department of Biology, McMaster University, Hamilton, Canada; Department of Biology University of Miami, Coral Gables, United States
Luis Alza
Department of Biology University of Miami, Coral Gables, United States; University of Alaska Museum and Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, United States; Centro de Ornitología y Biodiversidad - CORBIDI, Lima, Peru
Gabriele Nandal
Department of Biology, McMaster University, Hamilton, Canada
Department of Biology, McMaster University, Hamilton, Canada
Kevin G McCracken
Department of Biology University of Miami, Coral Gables, United States; University of Alaska Museum and Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, United States; Centro de Ornitología y Biodiversidad - CORBIDI, Lima, Peru; Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, United States; Human Genetics and Genomics, Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, United States
High-altitude environments require that animals meet the metabolic O2 demands for locomotion and thermogenesis in O2-thin air, but the degree to which convergent metabolic changes have arisen across independent high-altitude lineages or the speed at which such changes arise is unclear. We examined seven high-altitude waterfowl that have inhabited the Andes (3812–4806 m elevation) over varying evolutionary time scales, to elucidate changes in biochemical pathways of energy metabolism in flight muscle relative to low-altitude sister taxa. Convergent changes across high-altitude taxa included increased hydroxyacyl-coA dehydrogenase and succinate dehydrogenase activities, decreased lactate dehydrogenase, pyruvate kinase, creatine kinase, and cytochrome c oxidase activities, and increased myoglobin content. ATP synthase activity increased in only the longest established high-altitude taxa, whereas hexokinase activity increased in only newly established taxa. Therefore, changes in pathways of lipid oxidation, glycolysis, and mitochondrial oxidative phosphorylation are common strategies to cope with high-altitude hypoxia, but some changes require longer evolutionary time to arise.
