Off-campus UNL users: To download campus access dissertations, please use the following link to log into our proxy server with your NU ID and password. When you are done browsing please remember to return to this page and log out.

Non-UNL users: Please talk to your librarian about requesting this dissertation through interlibrary loan.

Adjusting to Life at High Elevations: Eco-Physiological and Genetic Insights from Andean Vertebrates

Natalia Gutierrez Pinto, University of Nebraska - Lincoln


Endotherms at high altitude face the combined challenges of cold and hypoxia. Cold increases thermoregulatory costs, and hypoxia may compromise the constant flow of oxygen required to fuel aerobic metabolism, ultimately affecting both aerobic thermogenesis and exercise capacity. Physiological adaptation to high-elevation environments can involve plastic (acclimatization) and evolved (genetic) changes that improve the transport and utilization of oxygen and metabolic substrates. In this dissertation, I compare closely related highland and lowland vertebrate taxa to infer possible patterns of physiological adaptation and the mechanisms that facilitate the colonization of high-altitude environments. In chapter 1, I tested for altitude-related variation in aerobic metabolism in five pairs of closely related Andean passerines with contrasting elevational ranges. If high elevation taxa physiologically adapted to their habitats, we expect consistent differences in metabolic rates (basal and maximal) and aerobic scope, in comparison with lowland species. I found no uniform elevational trend across all pairs of species, suggesting that there is no simple relationship between aerobic metabolism and native elevation. In chapter 2, I conducted a comparative analysis of DNA sequence variation involving two closely related Andean mouse species: one with a very broad elevational distribution (Phyllotis vaccarum) and another with a narrower, mostly lowland range (P. darwini). Since P. vaccarum may have evolved physiological tolerance to a broad range of environmental conditions (including high-elevation environmental extremes), I tested whether positive selection was more prevalent in the metabolic genes of P. vaccarum compared to P. darwini. I did not find conclusive evidence of positive selection in any individual gene involved in aerobic energy production. Together, my results confirm that there is no unique way of coping with the environmental challenges typical of high elevations. Results of these comparative analyses involving Andean birds and rodents generate new hypotheses that can be tested at different levels of biological organization.

Subject Area

Evolution and Development|Physiology|Genetics

Recommended Citation

Gutierrez Pinto, Natalia, "Adjusting to Life at High Elevations: Eco-Physiological and Genetic Insights from Andean Vertebrates" (2022). ETD collection for University of Nebraska-Lincoln. AAI29999556.