Features of Recent Codon Evolution: A Comparative Polymorphism-Fixation Study
Figure 1
Normalized frequencies of nucleotide changes at the polymorphic and fixed sites in amino-acid coding regions. Figures 1(a)–1(c) show the frequencies of polymorphism (Poly) and fixation mutations at the first (a), second (b), and third (c) positions of a codon. (d) Frequency of all the mutation data. Dotted lines indicate the polymorphism and solid lines indicate the fixation.
