PHOTOPIGMENTS UNDERLYING COLOR-VISION IN RINGTAIL LEMURS (LEMUR-CATTA) AND BROWN LEMURS (EULEMUR-FULVUS)

A recent examination of color vision in the ringtail lemur produced ev idence that these prosimians could make color discriminations consiste nt with a diagnosis of trichromatic color vision. However, it was uncl ear if this behavior reflected the presence of three classes of cone o r whether lemurs might be able to utilize signals from rods in conjunc tion with those from only two classes of cone. To resolve that issue, spectral sensitivity functions were obtained from ringtail lemurs (Lem ur catta) and brown lemurs (Eulemur fulvus) using a noninvasive electr ophysiological procedure, electroretinographic flicker photometry. Res ults from experiments involving chromatic adaptation indicate that the se lemurs routinely have only a single class of cone photopigment in t he middle to long wavelengths (peak sensitivity of about 545 nm); they also have a short-wavelength-sensitive cone pigment with peak of abou t 437 nm. The earlier behavioral results are suggested to have resulte d from the ability of lemurs to jointly utilize signals from rods and cones. The cone pigment complements of these lemurs differ distinctly from those seen among the anthropoids.