Mass-independent maximal metabolic rate predicts geographic range size of placental mammals

1.Understanding the mechanisms driving geographic range sizes of species is a central issue in ecology, but remarkably few rules link physiology with the distributions of species. Maximal metabolic rate (MMR) during exercise is an important measure of physiological performance. It sets an upper limit to sustained activity and locomotor capacity, so MMR may influence ability to migrate, disperse, and maintain population connectivity. Using both conventional ordinary least squares (OLS) analyses and phylogenetically generalized least squares (PGLS), we tested whether MMR helps explain geographic range size in 51 species of placental mammals.

2.Log body mass alone (OLS r2 = 0.074, p = 0.053; PGLS r2 = 0.016, p = 0.373) and log MMR alone (OLS r2 = 0.140, p = 0.007; PGLS r2 = 0.061, p = 0.081) were weak predictors of log range size.

3.However, multiple regression of log body mass and log MMR accounted for over half of the variation in log range size (OLS R2 = 0.527, p < 0.001). The ...