Model selection results.

The difference between the corrected Akaike information criterion (ΔAICc) was calculated for models fit to log-log transformed kC versus M data (from Grady et al.) or kD versus BMatMG data (from Werner and Griebeler), on a group-by-group basis. The models having ΔAICc = 0 (unshaded cells) are the best fit. Models having ΔAICc < 2 (bold numbers) have strong statistical support. The results show that substantial curvature effects exist for many groups. Models are defined in S2 Table. Best fits are plotted in S18 and S19 Figs.