Fig. 3
From: Raptor genomes reveal evolutionary signatures of predatory and nocturnal lifestyles
A functional trade-off of sensory systems in nocturnal birds. a The phylogeny of the α and γ olfactory receptor (OR) genes identified in 25 avian genomes. The phylogeny information was constructed for intact OR genes only using ClustalW2 software. Colors in the label means different avian species. b Selection constraints on sensory systems. Values for α, γ, and γ-c ORs are the diversity of ORs in each clade. For avian orders including two or more genomes (Strigiformes, Accipitriformes, Passeriformes, Falconiformes, and Pelecaniformes), the average diversity values were used. The diversity of α ORs in Piciformes and γ-c ORs in Psittaciformes were not calculated as the number of identified OR genes were smaller than two. Values for vision, hearing, and circadian rhythm are dN/dS ratios of each set of sensory system-associated genes. For avian orders including two or more genomes, dN/dS ratios of the ancestral branches were used. Three avian orders in red are nocturnal