Table 3.

Spectral sensitivities for RH2 visual pigments expressed in vitro. Substitutions and spectral shifts are relative to the ancestral sequence, which is common to many species in both the New World warblers and the Old World warblers. Positive shifts correspond to changes in λ_max toward longer wavelengths. All the observed shifts are small and spectral sensitivities of Rh2 pigments are not significantly different from each other. Residues in bold are inferred to have evolved under positive selection.

Substitutions	Estimated† λmax (nm)	Shift (nm)	Species‡
	503.5 ± 0.4	-	Ancestor
I7V; C85F; T284S	504.2 ± 1.0	+ 0.7	Spen
I7V; C85F; V227I; S340G	504.3 ± 0.1	+ 0.8	Sfus
T284S	504.6 ± 0.4	+ 1.1	Scas, Spet, Sstr

^†Standard errors are calculated from curve fits of 3 different absorbance measurements.

^‡Species that carry the sequence variant (see Fig. 2 for abbreviations).