Effect of colour vision status on insect prey capture efficiency of captive and wild tamarins (Saguinus spp.)

The colour vision polymorphism of most New World primates is a model system to study the function of colour vision. Theories for the evolution of primate trichromacy focus on the efficient detection and selection of ripe fruits and young leaves among mature leaves, when trichromats are likely to be better than dichromats. We examined whether colour vision status affected insect capture in groups of tamarins (Saguinus spp.) in captivity and in the field. Trichromatic tamarins caught more prey than dichromats, but dichromats caught a greater proportion of camouflaged prey than trichromats. The prey caught did not differ in size between the two visual phenotypes. Thus two factors may contribute to the maintenance of the genetic polymorphism of middle- to long-wavelength photopigments in platyrrhines: the advantage in finding fruit and leaves, which supports the maintenance of the polymorphism through a heterozygote advantage, and the dichromats' exploitation of different (e.g. camouflaged) food, which results in frequency-dependent selection on the different colour vision phenotypes