Figure 5. Branch and site selective pressures during the teleost lineage-specific duplications: A. OPN4m3/OPN4ma and B. OPN4x1/OPN4x2.

A punctual substitution (Y→C) was determined in the DRY motif in the OPN4m3 teleost melanopsin duplicant. Red lineages represent an episode of positive selection and the p+ parameter means the proportion of the positively selected sites. Black and grey circles represent the posterior probability level of G-protein coupling preference for each teleost fish amino acid sequence: 0.75–0.90 (grey circles) and >0.90 (black circles). The three-dimensional structure of the Gallus gallus OPN4m and OPN4x paralogs is also represented showing the occurrence of positive selection and functional divergence at the site level.