The among-group phylogenetic trees of exons (A) and introns (B) of the L/M opsin genes of gibbons. (A) The combined sequences of exons 3, 4 and 5 are considered. The human L and M, the crab-eating macaque L and M, and the mouse M opsin gene sequences are included. (B) The combined intron 3 and 4 sequences are considered. The human L and M opsin gene sequences are included. Bootstrap values over 80% are indicated at the branch nodes. Scale bars indicate the number of nucleotide substitution per site. Hag, H. agilis; Hla, H. lar; Hpi, H. pileatus; Nle, N. leucogenys; Ssy, S. syndactylus.