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DOI: 10.1055/s-0036-1572295
Genetic and Phenotypic Differentiation of an Andean Intermediate Altitude Population
Background: Highland populations living permanently under hypobaric hypoxia have been subject of extensive research because of the relevance of their physiological adaptations for the understanding of human health and disease. In this context, what is considered high altitude is a matter of interpretation and whilst the adaptive processes at high altitude (above 3000 m) are well documented, the effects of moderate altitude (below 3000 m) on the phenotype are less well established.
Methods: In this study we assessed physiological and anthropometric characteristics as well as genetic variations in two Andean populations: the Calchaquíes (2300 m) and neighboring Collas (3500 m). We compared their phenotype and genotype to the sea-level Wichí population. We measured physiological (heart rate, oxygen saturation, respiration rate and lung function) as well as anthropometric traits (height, sitting height, weight, forearm and tibia length; n = 179). We conducted genome-wide genotyping on a subset of the sample (n = 74) and performed various scans for positive selection.
Results: At the phenotypic level, increased lung capacity was indistinguishable between both Andean groups, regardless of their living altitude and different levels of constant hypoxia. Contrarily, growth reduction in distal limbs was only observed in the high altitude population. At the genomic level, Calchaquíes revealed strong signals around the Protein Kinase, cGMP-Dependent, Type I (PRKG1) gene, suggesting that the nitric oxide pathway may be a target of selection.
Conclusion: Overall, our study shows that some phenotypic and genetic differentiation also occurs at intermediate altitude in response to moderate lifelong selection pressures.