Figure 1.
Carnivora phylogeny, UGT1A6 mutations, and diet.
Shown is a simplified phylogeny of the Carnivora species evaluated in this study, indicating the deduced timing of disruptive UGT1A6 mutations (highlighted) found within the Felidae, Hyaenidae and Phocidae lineages. Shown at specific nodes are divergence times (in MYA) defining the upper and/or lower boundaries of each mutation based on published estimates [16], [18], [19] (details provided in Table 1). The inferred diets of each species based on the system proposed by Van Valkenburgh [27], [35] are denoted by the branch line color. Species were classified as hypercarnivores (>70% animal matter in diet), mesocarnivores (50-70% animal matter in diet), or hypocarnivores (<50% animal matter in diet) based on evidence given in Tables S2 and S3. Disruptive UGT1A6 mutations are only found in species classified as hypercarnivores. Note that for unknown reasons UGT1A6 could not be amplified by PCR in any of the Otariidae evaluated (indicated by “?”), while UGT1A1 was readily amplified and sequenced in those same species.
Table 1.
Mutations disrupting the reading frame of the UGT1A6 gene found in 18 different species of Felidae.
Figure 2.
Premature stop codon found in the brown hyena (Parahyaena brunnea) UGT1A6 coding sequence.
Shown are the UGT1A6 exon 1 nucleotide sequences (bp 253-297) of four brown hyenas aligned with UGT1A6 sequences from other species of Feliformia. A premature stop codon TGA (M10: bp274-276) was found in all brown hyenas evaluated at exactly the same position as the premature stop codon TGA (M1) found in the domestic cat and all other felid species evaluated. Also shown are a representative DNA sequence chromatogram, and the translated brown hyena and human UGT1A6 amino acid sequences.
Figure 3.
Frameshift mutation and premature stop codon found in the northern elephant seal (Mirounga angustirostris) UGT1A6 coding sequence.
Shown in panel (A) are the UGT1A6 exon 1 nucleotide sequences (bp 379-417) of 5 different northern elephant seals aligned with UGT1A6 sequences from other species of Caniformia, domestic cat, and human. A 1 bp insertion (M11: bp 398-399) was found in all northern elephant seals evaluated resulting in a reading frame shift relative to other species. Shown in panel (B) is the premature stop codon TAA (M12: bp 667-669) found in all northern elephant seals. Also shown in panels (A) and (B) are representative DNA chromatograms, and the translated northern elephant seal and human UGT1A6 amino acid sequences.
Table 2.
Nonsynonymous to synonymous nucleotide substitution frequency ratios (dN/dS) determined for Carnivora and non-Carnivora UGT genes using a maximum likelihood approach.