(902.3) A Test of Altitude-Related Variation in Aerobic Metabolism of Andean Birds

Poster Board Number: E442

Natalia Gutierrez-Pinto (University of Nebraska-Lincoln), Gustavo Londoño (Universidad ICESI), Mark Chappell (University of California Riverside), Jay Storz (University of Nebraska-Lincoln)

Endotherms at high altitude face the combined challenges of cold and hypoxia. Cold increases thermoregulatory costs, and hypoxia may limit both thermogenesis and aerobic exercise capacity. Consequently, in comparisons between closely related highland and lowland taxa, we might expect to observe consistent differences in basal metabolism (BMR), maximal metabolism (MMR), and aerobic scope. Previous broad-scale comparative studies of birds have revealed no association between BMR and native elevation; however, altitude effects may be detectable in fine-grained comparisons between pairs of ecologically similar, closely related species that are native to different elevations. Moreover, it remains unknown if exercise-induced MMR and aerobic scope exhibit consistent patterns of altitude variation. To evaluate whether there is an association between altitude and metabolic rates, we tested for altitude-related variation in aerobic metabolism in 10 Andean passerines representing five pairs of closely related species with contrasting elevational ranges. We used a paired-lineage design such that the five pairwise comparisons were phylogenetically independent. In our small sample of Andean passerines, we found a significant effect of elevation on mass-corrected BMR, MMR, and aerobic scope in most but not all cases. BMR and MMR were significantly higher for the high-elevation species in three pairs, two of which also had a significantly higher aerobic scope at high-elevation. One pair did not exhibit significant elevational differences in BMR, MMR, or aerobic scope. Overall, we could not document a uniformly consistent elevational trend in the species analyzed.

Support or Funding Information

This research was supported by grants from the National Institutes of Health (HL087216) and the National Science Foundation (OIA-1736249 and IOS-1927675) to J. F. S.; R. C. Lewontin Graduate Research Excellence Grant and University of Nebraska SBS Special Funds to N. G. P.; and the research agreement between Icesi University and EPSA-Celsia signed in 2016 to G. A. L.