Abstract: The study of metabolism concerns the study of biological processes, their rates and requirements, and how they change and interact in different contexts. It is a basis for understanding the energetic requirements of species and how these requirements are affected by evolutionary history, ecological strategies, and environmental conditions. Metabolic measurements of amphibians were conducted across 10 field sites that spanned between 200 meters above sea level and 5,300 meters above sea level in the buffer zone of Manu National Park. Resting metabolic rates (RMR) were determined by measuring the change in CO2 over time using an infrared gas analyzer in a closed system where the amphibian was unmoving for at least 30 minutes. Measurements were taken at night and during the day at ambient temperatures to examine thermal sensitivity of metabolic rate. Results were analyzed at the species level, across elevational ranges and among populations, to examine variation within species. Additionally, phylogenetic comparative analyses were used to examine the extent to which metabolic characteristics are constrained by evolutionary history and how they have evolved across the phylogenetic tree of amphibians. A total of 114 species of amphibians in 14 families, including anurans, salamanders, and caecilians, were found across the 5,000 meter gradient. In a subset of species sampled, there is little intraspecific variation in RMR across elevation, suggesting little capacity for plasticity and/or adaptation in response to ongoing anthropogenic climate change. However, there is substantial variation of resting metabolic rate at higher taxonomic levels as well as across elevation, suggesting that the effects of ongoing anthropogenic climate change vary among species and environments. Notably, the thermal sensitivity of metabolic rate of tropical amphibians is substantially higher than has been found in past metabolic studies in the group (of principally temperate taxa). Current modeling approaches to predict the metabolic impacts of climate change in amphibians may be severely underestimating the impacts on tropical amphibians as a result of higher thermal sensitivities.
