Chapter 2 Effect of stabilizing selection on trait distribution


Figure 2.2 Changes in a hypothetical bivariate trait distribution induced by stabilizing selection. All of the distributions are normal before and after selection; 95% confidence ellipses are shown before selection (blue) and after selection (black).  The principal axes (principal components or eigenvectors) of the two ellipses are also shown. The bivariate trait mean is centered about an optimum, so selection changes the variances and covariance of the trait distribution, from P to P*, but not its bivariate mean. Trait correlations before and after selection are shown as r and r*, respectively.