A STATISTICAL-ANALYSIS OF MAMMALIAN RATES OF METABOLISM

1. Much controversy has attended discussions of the factors responsible for variation in rate of metabolism in mammals. 2. Potential factors were examined here by analysis of covariance to determine whether they correlate with basal rate of metabolism in mammals. 3. Variation in body mass, taxonomic affiliation, food habits, climate, activity level, propensity to enter torpor and form of reproduction accounts for almost all variation in the basal rate of metabolism in mammals. 4. In all analyses body mass had the greatest impact on basal rate. Often it was the only factor to influence basal rate in small or ecologically constricted sets of species. 5. As the number of species and the ecological diversity of the assemblage increased, the number of factors significantly associated with basal rate increased. 6. In several sets of species the exclusion of taxonomic affiliation brought one or more ecological factors into significance. This pattern suggests that much of the correlation of basal rate with taxonomic affiliation indirectly reflects ecological correlates.