Fig. 6.

—Proposed evolution of C6OST genes through the vertebrate whole-genome duplications (1R, 2R and 3R) (left) and C6OST gene repertoires in representative vertebrate species (right). A and B indicate alternative duplication scenarios through 1R/2R. The uncertain divergence of jawless vertebrates relative to 1R and 2R is indicated by dashed lines. Crossed-over boxes indicate gene losses. Open boxes indicate genes with unresolved phylogenetic positions. Some species-specific or lineage-specific duplicates are indicated by “X2” etc. within boxes. Asterisks indicate species included in the larger phylogenies shown in supplementary figures S1–S5 and S7, Supplementary Material online.