Animals at high altitudes use a variety of mechanisms to acquire sufficient oxygen despite low atmospheric pressure. Individual animals can shift their respiratory strategies in real time, just as humans increase the concentration and size of red blood cells during high-altitude training. Alternatively, high-altitude populations can genetically adapt by natural selection over generations, effectively optimizing their respiratory systems for low ambient oxygen pressure. This project will characterize the high-altitude respiratory strategies of dozens of wild bird species. Study taxa comprise pairs of related high-altitude and low-altitude populations at different levels of evolutionary divergence. International teams will sample birds along elevational gradients in the Andes to evaluate the structure and performance of critical respiratory system components, including heart, lungs, blood, hemoglobin, and the hypoxia-induced gene-expression cascade. With these data, this project will (1) develop a model of the time-course of high-altitude adaptation and (2) describe the diversity of solutions to this common physiological challenge. This new model and comparative data will facilitate inference of biogeographic history through integration of physiological and phylogenetic information. The results will reveal the contribution of respiratory specialization to the uniqueness and diversity of the Andean avifauna.
American and Peruvian students will develop international partnerships during the project's research expeditions. Specimens and linked data will be archived in museum collections and online databases. Andean bird lineages provide analogues to high-altitude human populations and their hypoxia defense mechanisms are of broad interest due to the profound role of hypoxia in human pathology.
