Fig. 5

Relationships between MI3 and feeding efficiency as TFI (top) and EA (bottom). The blue line indicates the regression line predicted in the GLM quadratic model (the best model for EA, coefficient of MI32 = 0.12, P = 0.02, AIC = -73.16, ΔAIC = 6.48), providing experimental evidence on the potential disadvantage of the intermediate phenotype. MI3 represents the morphological index for mouth narrowness, determined by the residual in the linear regression for mouth width by mouth length