Nonsynonymous to synonymous nucleotide substitution frequency ratios (dN/dS) determined for Carnivora and non-Carnivora UGT genes using a maximum likelihood approach.

1P value for likelihood ratio test comparing log-likelihood values obtained from a branch model in which dN/dS values were estimated for the lineage of interest (alternative model) and an equivalent model (null model) in which the lineage dN/dS value was fixed to the value originally obtained for all species (average value). P<0.05 was considered significant with one degree of freedom. 2Number of sampled taxa and unique translated amino acid sequences (seq.) used in each analysis. Differences between the numbers of taxa and sequences within each group arise from the presence of multiple UGT1A6 genes in mouse (2) and horse (3), as well as exclusion of any sequences found to be identical to any other sequence after cropping (see Table S1 and Table S6 for details).