Fig. 1.

Phylogenetic tree of the vertebrate PDE6 catalytic subunit genes. The phylogenetic maximum likelihood method was used to obtain the tree, rooted with the human PDE5A and PDE11A sequences. The three-letter abbreviations represent species and the number or Roman numeral represents chromosome, linkage group, scaffold, contig or NCBI accession number. The coloured boxes include the sequences that cluster together with the three different human PDE6 catalytic subunit genes. A more detailed PhyML tree with regard to birds and non-avian reptiles are presented in Additional file 3: Figure S1