Principal component analysis of shape coordinates. Scatter plot of the first two principal component scores for the 14 sex-specific mean shapes. The two mean shapes for each population are connected by a grey line to indicate the direction of sexual dimorphism. The deformation grids on the left and the right side visualize the shape change depicted by PC 1; they are deformations of the mean shape to shapes corresponding to minus and plus 0.07 units along the PC 1 axis. Similarly, the top and bottom deformation grids visualize shape change along PC 2. See the Methods section for abbreviations of populations.