Figure 1.
Relationship between BMR and (a) ambient temperature (Ta), (b) annual ambient temperature range (Tr) and (c) intra-annual coefficient of variation for precipitation (PCV). To remove the potential confounding effects of body mass and collinearity between environmental variables, residuals are presented. Residuals are calculated as the difference between measured and predicted values (i.e. BMR residuals in (a) are calculated as measured log BMR minus log BMR as predicted by log M, Tr and PCV; Ta residuals are calculated as Ta minus Ta as predicted by log M, Tr and PCV). Solid line is the phylogenetically correct and mass-independent correlation between BMR and the environmental variable, plotted through the bivariate mean and shown as ±1 s.e. of the coefficient from table 2 (dashed lines).