Features of Recent Codon Evolution: A Comparative Polymorphism-Fixation Study

Figure 3

Normalized difference of codon changes (gain and loss) at polymorphic and fixes sites. Codons are ordered in the ascending order of frequencies in human codon usage based on the Codon Usage Database. The solid vertical line separates rare and nonrare codons. The 10 rarest codons are shown in the left side of the dotted line.