Meeting Abstract
The amount of energy devoted to survival, growth, and reproduction governs the speed of life, or the position of a species on a continuum of slow to fast life histories. Energy availability is governed by metabolic rate, which is the rate of resource uptake and allocation. Thus, metabolic rate likely shapes life histories, and environmental factors act to shape metabolic rate. Yet, few studies have explored the relationships between metabolic rate, environmental factors, and life history. As metabolic rate is most commonly assessed by measuring oxygen consumption in the laboratory, this often precludes collecting metabolic data for large-bodied, aquatic organisms. Previous work has suggested that metabolic rate and respiratory morphology are linked, and that the surface area of the lungs or gills can act as a proxy for metabolic rate. To date, the relationship between metabolic rate and respiratory surface area has not been explicitly explored. Here, we analyze the utility of using respiratory surface area as a proxy for metabolic rate using the theoretical framework of the Metabolic Theory of Ecology. We first test the predictions of the Metabolic Theory of Ecology by examining the body-mass scaling of metabolic rate in vertebrates. Then, we compare the body-mass scaling of respiratory surface area in vertebrates to that of the Metabolic Theory of Ecology predictions. We finally assess how respiratory surface area fits into the Metabolic Theory of Ecology framework. Our results show that the allometries of metabolic rate and respiratory surface area for our vertebrate dataset scale similarly, and that including respiratory surface area in the Metabolic Theory of Ecology framework accounts for a significant portion of the remaining variation.
