Sensitivity spectra of three photoreceptor cells with different visual pigments (three solid curves = R(λ)) and reflectance spectrum of a male nuptial color (a broken curve = S
(λ)) (a), visual sensitivity (b), female preference for male coloration (c), all in the initial condition, and environmental illumination spectra at different depth (d). a) The peak wavelengths of R(λ) for SWS pigment alleles (λB1 and λB2) are 450 nm, those of MWS (λG1 and λG2) are 500 nm and those of LWS (λB1 and λB2) are 550 nm. The peak wavelength of Sm(λ) is 500 nm. b) The total visual sensitivity for 15 different Sm(λ) is calculated as zP(Sm), where zP(Sm) is calculates by using equation 2 and z is constance (see text). c) Relative strength of female preference to 15 different Sm(λ). Values for female preference are relative values when the maximum F was set to 1. d) A broken line indicates a gradient of predominant wavelength of light along depth. y is vertical axis of the simulation space, and spatial point at y = 1000 corresponds to the water depth of about 10 m (Fig. 4).