Meeting Abstract

141.4  Monday, Jan. 7  Cellular metabolic rate is influenced by life-history traits in tropical and temperate birds. JIMENEZ, A.G.*; VAN BROCKLYN, J.; WILLIAMS, J.B.; The Ohio State University jimenez.102@osu.edu

Tropical and temperate bird species tend to live on opposite sides of the life-history continuum, with tropical birds falling on the “slow” end of the spectrum characterized by low annual reproductive output and low mortality rate, and temperate birds on the “fast” end characterized by rates of reproduction and mortality that are high. Although it is thought that physiological processes underlie many life-history trade-offs, the precise linkages between an organism’s life history and the function of its organs, tissues, and cells remain unclear. Previous work in our lab has demonstrated that tropical birds have a significantly lower basal metabolic rate and peak metabolic rate compared with their temperate species counterparts. We have also found that a contributing factor to the reduced rate of metabolism in tropical birds is that they have smaller metabolically-active organs, such as heart, liver, kidneys, and pectoral muscles, compared with similar-sized temperate species. However, a fundamental challenge facing physiological ecologists is an understanding on how variation in life-history at the whole-organism level might be linked to cellular function. Here, we compared various parameters of cellular metabolism in 34 species of phylogenetically paired tropical and temperate bird species. Using an XF24 Seahorse extracellular oxygen analyzer, we measured basal and maximal cellular oxygen consumption (OCR) and the rate of glycolysis (ECAR). We found that in most bird pairings, there was a lower basal and maximal oxygen consumption in tropical species, which is in accordance with a slower pace-of-life.