ML estimates and AIC values of the present models for the 1-PAM amino acid substitution matrices of JTT, WAG, and LG, and the 1-PAM codon substitution matrix of KHG.

aIf the value of a parameter is parenthesized, the parameter is not variable but fixed to the value specified.b for JTT, for WAG, for LG, and for KHG; see text for details.c #parameters with for JTT, for WAG, for LG, and the value of is unknown for KHG; see text for details.dThe value in the parenthesis corresponds to the one for the KHG codon substitution probability matrix.eNote that these ratios are not the ratios of the rates per site but per codon; see text for details.