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Many high-altitude vertebrates have evolved increased capacities in their oxygen transport cascade (ventilation, pulmonary diffusion, circulation and tissue diffusion), enhancing oxygen transfer from the atmosphere to mitochondria. However, the extent of interspecies variation in the control processes that dictate hypoxia responses remains largely unknown. We compared the metabolic, cardiovascular and respiratory responses to progressive decreases in inspired oxygen levels of bar-headed geese (Anser indicus), birds that biannually migrate across the Himalayan mountains, with those of Andean geese (Chloephaga melanoptera) and crested ducks (Lophonetta specularioides), lifelong residents of the high Andes. We show that Andean geese and crested ducks have evolved fundamentally different mechanisms for maintaining oxygen supply during low oxygen (hypoxia) from those of bar-headed geese. Bar-headed geese respond to hypoxia with robust increases in ventilation and heart rate, whereas Andean species increase lung oxygen extraction and cardiac stroke volume. We propose that transient high-altitude performance has favoured the evolution of robust convective oxygen transport recruitment in hypoxia, whereas life-long high-altitude residency has favoured the evolution of structural enhancements to the lungs and heart that increase lung diffusion and stroke volume.

Item Type:	Refereed Article
Keywords:	altitude, ventilation, cardiac output, metabolism, goose, duck
Research Division:	Biological Sciences
Research Group:	Zoology
Research Field:	Animal physiological ecology
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the biological sciences
UTAS Author:	Frappell, PB (Professor Peter Frappell)
ID Code:	123615
Year Published:	2017
Web of Science® Times Cited:	14
Deposited By:	Ecology and Biodiversity
Deposited On:	2018-01-15
Last Modified:	2018-05-30
Downloads:	127 View Download Statistics