Fig. 4. The relationship between flight muscle mass (g) and body mass (g) for hummingbirds: (A) raw species data (y=0.34x+0.39, r²=0.94, P<0.0001); (B) independent contrasts (y=1.25x, r²=0.73, P<0.0001). The regression using independent contrasts is forced through the origin (Garland et al., 1992). The phylogenetic hypothesis used for this analysis is the same as for Fig. 1.