Meeting Abstract

 

P1-90  Friday, Jan. 4 15:30 – 17:30  The effect of elevation on the aerobic scope of Andean birds GUTIERREZ-PINTO, N*; LONDOñO, GA; CHAPPELL, MA; STORZ, JF; University of Nebraska-Lincoln; Universidad ICESI; University of California Riverside; University of Nebraska-Lincoln nguti@huskers.unl.edu

The aerobic scope (VO_2max/BMR) defines an animal’s endurance during energy-demanding behaviors necessary for survival. Additionally, the maximal rate of aerobic activity in vertebrates is determined by an individual’s ability to obtain, transport, and utilize oxygen (O₂), which is in limited supply at high-elevations (i.e. hypoxia). Hypoxia is especially acute for small, active endotherms like passerine birds that cannot use metabolic suppression as a means of reducing O₂ requirements. Consequently, it can be expected that there are compensatory physiological mechanisms in place to maintain VO_2max and BMR at high elevations. Nevertheless, efforts to evaluate the causes of variation in maximal energy use across bird species have not been explicitly developed in the context of elevation. In this study, we compare five pairs of closely-related bird species with contrasting elevational ranges in the Colombian Andes to test for associations between native elevation range and aerobic scope. Preliminary results suggest that high- and low- altitude species have similar VO_2max, BMR, and aerobic scopes, which should reflect changes in the underlying architecture and mechanisms (e.g. size of relevant organs or Hemoglobin-O₂ affinity) that allow high-elevation individuals to maintain the same rate of basal and maximal O₂ utilization in spite of low O₂ availability.