Fig. 2

Path diagram of the best-fitted overall model for tarsus asymmetry (SEM). The number associated with each arrow is the parameter estimate. Thick solid lines are significant paths (P < 0.05), dashed lines are non-significant. The number indicates non-standardized parameter estimates; the number in parenthesis indicate the standard error. (Path diagrams of species-specific models, test statistics and full SEM results are detailed in Additional file 1: Tables S2–S5, Figs. S3, S4)