Fig. 3
From: Gene loss, adaptive evolution and the co-evolution of plumage coloration genes with opsins in birds
Lineage-specific visual adaptations in birds. a Box plots summarizing the lineage-specific evolutionary rates in bird species that possessed a violet (VS) or ultra-violet (UVS) sws1 opsin. Colored circles identify the observed ω-lineage for Passeriformes (yellow) and Psittaciformes (green). b Distance plot indicating the lineages with an outlier evolutionary behavior in the opsin gene family. Species highlighted with red circumferences are birds of prey and those in blue are water birds. The species numbering system is the same as in Fig. 1