Figure 4. Trajectories for synonymous, nonsynonymous, and intergenic point mutations.

a, Synonymous mutations, scaled so mean of five nonmutator populations (excluding point-mutation and IS150 hypermutators) is unity at 50,000 generations. b, Nonsynonymous mutations, scaled using same rate as synonymous mutations after adjusting for sites at risk for both classes. c, Intergenic point mutations, scaled using same rate as synonymous mutations after adjusting for sites at risk. Each symbol shows the mean for sequenced genomes from a nonmutator or premutator lineage. Colours are as in Figure 1. Note discontinuous scale; populations with zero mutations are plotted below. Black lines connect grand means; shading shows standard errors calculated from replicate populations.