Figure 9: Human–chimpanzee–mouse–rat tree with branch-specific KA/KS (ω ) values.
From: Initial sequence of the chimpanzee genome and comparison with the human genome
a, Evolutionary tree. The branch lengths are proportional to the absolute rates of amino acid divergence. b, Maximum-likelihood estimates of the rates of evolution in protein-coding genes for humans, chimpanzees, mice and rats. In the text, ωhominid is the KA/KS of the combined human and chimpanzee branches and ωmurid of the combined mouse and rat branches. The slight difference between ωhuman and ωchimpanzee is not statistically significant; masking of some heterozygous bases in the chimpanzee sequence may contribute to the observed difference (see Supplementary Information ‘Gene evolution’).
