intraspecies relationship between tissue turnover and metabolic rate in rats

• Published in: Ecological research 2014-09, Vol.29 (5), p.937-947
• Main Authors: Kraeer, Kimberly, Arneson, Lynne S, E. MacAvoy, Stephen
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Behavioral Sciences; Biological and medical sciences; Biomedical and Life Sciences; Blood; correlation; Ecological function; ecologists; Ecology; equations; Evolutionary Biology; Forestry; Fundamental and applied biological sciences. Psychology; General aspects; half life; Isotope turnover; isotopes; Life Sciences; Metabolic tissue replacement; Metabolism; migratory behavior; Norway rat; Nutrient availability; Nutrient sources; Original Article; oxygen; Plant Sciences; Rats; Rattus norvegicus; resting metabolic rate; Rodents; Synecology; Tissues; Zoology
• ISSN: 0912-3814; 1440-1703
• DOI: 10.1007/s11284-014-1182-x

Ecologists interested in studying fluctuating relationships between consumers and nutrient sources are increasingly involved in modeling the rate at which consumers incorporate dietary components. In mammals a correlation between resting metabolic rate (RMR) and tissue turnover may exist across a range of species. Less is known about the variation of tissue turnover rate within a species, and how that correlates with RMR. Here we examine two strains of rats (Rattus norvegicus) with different RMR to test whether variation in RMR is positively correlated with tissue turnover rate within a species. If RMR, a relatively simple measurement, can be correlated with tissue turnover, then this relationship could be used to better interpret ecological functions, including impact of migratory or seasonally available nutrient sources. Here, the changing isotope signature in rat whole blood was modeled using a modified exponential decay equation and a reaction progress variable model. The modeled rate of turnover, metabolic rate (O₂ consumed), and mass were then compared between strains of rats. The mass and RMRs (conditions during which RMRs were determined modified from the ideal, as outlined in the Methods) were significantly different between strains, but half-life and the metabolic tissue replacement component of turnover (as opposed to turnover from mass gain) were not. No significant correlation was found between RMR and metabolic tissue replacement between the strains. Results suggest that within a species showing a range of RMRs, blood tissue turnover should not vary significantly.