Fig. 2
From: Adaptive genomic evolution of opsins reveals that early mammals flourished in nocturnal environments
Selective signatures in the mammalian OPN1sw1 opsin. Schematic view of the bovine rhodopsin highlighting the visual opsins spectral tuning sites ([19, 20]): OPN1lw (red), RH2 (green), OPN1sw2 (blue), OPN1sw1 (violet) and RH1 (black). Shared spectral tuning sites are indicated by shared colours. Residues highlighted in red experienced positive selection in mammals. The bar plot depicts the amino acid composition of the OPN1sw1 93 spectral tuning site accounting for the nocturnal and diurnal species and the eutherian orders (or infraclass in the case of marsupials) in which these amino acids were found