Fig. 5.—

Strong clients evolve faster than weak clients. (A) We find that strong clients evolve faster than weak clients on intermediate evolutionary time scales, measured as the rate of nonsynonymous substitutions (Wilcoxon rank-sum test, P < 2.2 × 10 ^{− 16}). (B) On long evolutionary time scales, we also find that strong clients evolve faster than weak clients (Wilcoxon rank-sum test, P = 2.3 × 10 ^{− 3}). The thick horizontal line in the middle of each box represents the median of the data, whereas the bottom and top of each box represent the 25th and 75th percentiles, respectively. Note the logarithmic scale on the y-axis in (A).