ABSTRACT
Present-day inhabitants of Himalayan, Andean, and Ethiopian highlands exhibit a wide range of physiological responses to chronic hypoxemia inherent to life at high altitude. Physiological assessments and analyses throughout the past several decades suggest each population adapted distinct mechanisms for oxygen transport and utilization, which have been essential for survival under such challenging environmental conditions. Recent analyses indicate many of the same genomic pathways (e.g. the hypoxia inducible pathway), but distinct specific genetic markers contribute to the variation observed in key traits among these continental groups and reflect unique and complex evolutionary histories. Physiological variation is also notable within populations and, in a few cases, has been linked to putatively adaptive genetic targets of natural selection. Such findings provide greater insight into potential mechanisms of hypoxia adaptation that are actively investigated using state-of-the-art -omics techniques. In addition to human populations, various species exposed to generations of environmental hypoxia exhibit similar physiological and genetic adaptations, providing important examples of convergent adaptation to hypoxia.
