Figure 4

Wing coloration and color discrimination of Papilio xuthus. A Reflectance spectra measured with a bifurcated probe from wing areas 1–5. B Wavelength discrimination as a function of wavelength, ∆λ(λ), following from behavioral experiments (after Figures 1b and 4d of [3]) and the spectral sensitivity, S(λ), measured by intracellular recordings, of the four photoreceptor types that were concluded to participate in spectral discrimination; the normalized S(λ)-values were multiplied with a factor 10 to facilitate visualization. The dotted vertical lines, with interdistance 80 nm, are at the wavelengths where ∆λ was about minimal.