Figure 3.

Boxplot of relative weapon muscle mass for all species. (a) relative muscle mass A = muscle mass/body size. (b) Relative muscle mass B = muscle mass/body mass. Shades of red indicate significant relationships between residual RMR and residual weapon size. Shades of blue indicate no significant relationship between residual RMR and weapon size. Error bars represent 95% confidence intervals around mean relative muscle mass. *Wet muscle mass was measured for rhinoceros beetles in place of dry muscle mass. **Relative muscle mass B calculated for stag beetles as mean muscle mass/mean body mass.