Fictive Quadrupedal Walking

This week Arikawa et al. find that in the small white butterfly, the sexes actually see the world differently. The authors compared the male and female eyes of Pieris rapae crucivora that are equipped with three classes of photoreceptors sensitive to short-wavelength light. In both sexes, the authors detected mRNAs for three novel opsins, one per type of photoreceptor. Intracellular recordings from female photoreceptors revealed spectral sensitivity peaks in the ultraviolet (UV), violet (V), and blue (B) wavelengths. Male short-wavelength photoreceptors likewise fell into three classes, but in place of violet they had a double-peaked blue (dB) sensitivity. The male dB spectral sensitivity results from a fluorescent protein, excited by blue and UV light, that acts as a selective filter. The authors speculate that the male’s high sensitivity in the blue range helps discriminate between the colors of the male and female wings.