Meeting Abstract

38.1  Jan. 5  Faster with use: exercise affects turnover rate of carbon isotopes in some but not all organs MCWILLIAMS, S.R.*; BAUCHINGER, U.; KEIL, J.; STARCK, J.M.; University of Rhode Island; University of Munich; University of Munich; University of Munich srmcwilliams@uri.edu

Most contemporary applications of stable isotopes in ecology and physiology rely on untested assumptions about the turnover rate of isotopes in various tissues. These assumptions are particularly relevant for studies that test hypotheses about how increased energy demands, like those associated with exercise, affect organ size and cell turnover. We studied turnover rates of carbon isotopes in 16 different tissues of Zebra Finch (Taeniopygia guttata) that were either exposed to cold temperatures, regularly exercised, or sedentary. Although cold-acclimated and exercised birds had higher energy demands and ate significantly more than sedentary birds, we detected no significant differences in size of organs associated with digestion. However, carbon turnover rates of organs associated with exercise (e.g., pectoral muscle, heart) were significantly more rapid in exercised birds compared to cold-acclimated and sedentary birds. In general, carbon turnover rate differed substantially between organs with small intestine and liver the most rapid and leg muscle among the slowest. These measures of carbon turnover rate provide insights into which tissues are best for accurately assessing interactions among key life history stages of the annual cycle such as reproduction, molt, and migration.