Demonstration of a foraging advantage for trichromatic marmosets ( Callithrix geoffroyi ) dependent on food colour

Abstract

It has been suggested that the major advantage of trichromatic over dichromatic colour vision in primates is enhanced detection of red/yellow food items such as fruit against the dappled foliage of the forest. This hypothesis was tested by comparing the foraging ability of dichromatic and trichromatic Geo¡roy's marmosets (Callithrix geo¡royi) for orange-and green-coloured cereal balls (Kix 1 ) in a naturalized captive setting. Trichromatic marmosets found a signi¢cantly greater number of orange, but not green, Kix 1 than dichromatic marmosets when the food items were scattered on the £oor of the cage (at a potential detection distance of up to 6 m from the animals). Under these conditions, trichromats but not dichromats found signi¢cantly more orange than green Kix 1 , an e¡ect that was also evident when separately examining the data from the end of the trials, when the least conspicuous Kix 1 were left. In contrast, no signi¢cant di¡er-ences among trichromats and dichromats were seen when the Kix 1 were placed in trays among green wood shavings (detection distance 5 0.5 m). These results support an advantage for trichromats in detecting orange-coloured food items against foliage, and also suggest that this advantage may be less important at shorter distances. If such a foraging advantage for trichromats is present in the wild it might be su¤cient to maintain the colour vision polymorphism seen in the majority of NewWorld monkeys.

Sensory information and associative cues used in food detection by wild vervet monkeys

“…In more open habitats, animals may become reliant on vision and color vision may aid this adaptation. For instance, in polymorphic marmosets (Callithrix geoffroyi), Caine and Mundy (2000) found that trichromats were better than dichromats at detecting food at distances up to 6 m. To our knowledge, food detection by wild primates at ranges greater than 6 m has not been examined relative to their visual system, but species in open areas with color vision may be at a visual advantage.…”

Photopigments and colour vision in New World monkeys from the family Atelidae

“…The maintenance of these gene polymorphisms implies that trichromacy must be advantageous. Over the years a number of potential advantages have been suggested (Mollon et al 1984;Mollon 1991;Jacobs 1997), but the only empirical evidence on the matter comes from a recent experiment claiming that trichromatic tamarins are more apt at foraging for food in a semi-natural environment than their dichromatic colleagues (Caine & Mundy 2000).…”

Mapping behavioural evolution onto brain evolution: the strategic roles of conserved organization in individuals and species

“…This produces better 'colour acuity' in the greenbrown regions of colour space, with many plausible adaptive advantages [15][16][17][18]. Startlingly, the identical modification may be 'knocked in' to the retinas of mice or dichromatic monkeys, who can in short order learn to make behavioural use of the new colour information, with no other genetic changes in their nervous systems [19,20].…”