Fig. 3.

Proposed evolutionary history and gene repertoire of the PDE6 inhibitory subunit genes. Important events in the evolution of this gene family 1) Emergence of the ancestral PDE6 inhibitory subunit gene, before 2R. 2) Loss of PDE6I in the ancestor of amniotes. 3) Loss of the second intron of the coding region of the putative PDE6H 3R duplicates. 4) Local duplication of one of the PDE6H 3R duplicates. 5) Loss of the first intron of the coding region in one of the PDE6H 3R duplicates. Small arrowheads represent stop codons or frame shift mutations in the coding sequence. The orthology assignment of the genes was done according to conservation of synteny and exon-intro organisation. The column to the right shows identified genes whose assignment was not possible