Figure 4.—

The probability that a beneficial amino acid of fitness rank j will be the next to spread to fixation, given that an amino acid of fitness rank i is the current wild type (P_ij), plotted against the amino acid's marginal relative fitness (w_j), both scaled between 0 and 1. P_ij was calculated for V3 site 25 residues, using Equation 2 (see text) with selection coefficients calculated relative to residues K (circles), A (squares), and Q (triangles). One-letter amino acid codes are shown. The diagonal line is for y = x.