FIG. 4.

Upper and middle graphs show mean synonymous mutation rates and mean nonsynonymous mutation rates, respectively, for each pmp determined by the method of Nei and Gojobori (p-distance model). Minimum and maximum values represent lower and upper limits of the 95% CI of the estimate, while values plotted at the horizontal bar level represent the mean estimates. The lower graph shows the nonsynonymous- to synonymous-mutation ratio for each pmp determined on the basis of the mean estimates shown in the prior two graphs.