Severity and frequency of overlapping DAMs. (A) The proportion of DAMs that overlap with inter-specific variation at positions evolving with different evolutionary rates. Six rate index categories that show differences among species (Table 1) were pooled into three categories in order to make sample sizes large enough, because only 203 DAMs show overlap with inter-specific variations. The total number of DAMs and the overlapping DAMs are given in parenthesis. The hatched area indicates the fraction of DAMs (10.4%) that overlap with inter-specific fixed differences over all the variable amino acid positions (203/1961). (B) The average Grantham distance of DAMs (red), inter-specific variations (green), and the overlapping mutations (hatched). The numbers of mutations and differences are given in parenthesis. The error bars show standard error of the mean.