Fig. 2.

Medians of ε_πnor from linear regression for different categories of substitutions. Medians of ε_πnor from linear regression are shown for (A) nonsynonymous and synonymous substitutions in all genes, (B) nonsynonymous and synonymous substitutions that are in single-substitution genes and other genes, (C) nonsynonymous substitutions that changed amino acid chemical properties in different ways, (D) nonsynonymous substitutions increasing basicity or acidity of the amino acids, and (E) nonsynonymous substitutions that compensate or reinforce the chemical property changes of the nearest amino acid substitutions. Data of 400-bp window are shown, for which all comparisons are statistically significant with Mann–Whitney U test except for the comparisons between “compensatory–change charge” and “reinforcing–change charge”. Numbers of substitutions of each category are in parenthesis.