Caracterização cromática das fontes alimentares de origem vegetal do sagui-do-cerrado (Callithrix penicillata, PRIMATES)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The colour vision ability depends on the presence of different classes of retinal photoreceptors and subsequent compatible neural tracts. The basic mammalian colour vision status is dichromacy, resulting of the presence of two different types of cones. Primates and some marsupials are exceptions for this status, which may present trichromatic colour vision. In the New World, most of the primate species have a visual polymorphism that underlies obligatory dichromatic males and dichromatic or trichromatic females. Recent theories correlate the trichromatic colour vision with an advantage in foraging reddish or red-yellowish items against a green leaf background. Here, we intent to characterize some food items eaten by the black-eared-marmoset and assess the possible differential abilities of dichromats and trichromats in foraging activities for these items. In the present work, we measured the reflectance spectra of food items present in the home range of Callithrix penicillata. Within 11 species measured, six are found in the marmoset diet, four are probably eaten and one is possibly toxic. Leaves from gouged and ungouged gum trees were also measured. These spectra were multiplied by the photoreceptor sensitivity curve and the illuminant spectrum, resulting in the quantum catch for each photoreceptor type. The quantum catch was analyzed under two complementary models: chromaticity diagrams and chromatic distance. The chromatic distance model considered 10 different foraging situations. The chromaticity diagrams suggest that most of the plant items measured would be detected by all phenotypes. The species Miconia burchelli, M. ferruginata, M. albicans and Sp.1 are exceptions, with targets represented within leaves. The chromatic distances support the chromaticity diagram findings, where the same species have distances below the detectable threshold in several situations. The immature fruit of Schefflera macrocarpa also had values below threshold. Despite the small differences in detection capacity within phenotypes, the same species detected by trichromats were also detected by dichromats. For gum providing trees, the chromaticity diagrams showed differences between gouged-tree leaves and ungouged-tree leaves especially in luminance sub-channel for S. macrocarpa, for all phenotypes. According to the chromatic distance model, the separation of leaves from gouged and ungauged trees were under the threshold value for a detectable difference. This work suggests that the colour vision phenotype has little influence on the foraging activities by Callithrix penicillata, which failed to show constant trichromatic or dichromatic advantages in the detection of fruits within these plant species in two different light conditions. Considering that dichromats may have other advantages, such as detection of predators and cryptic food items, these phenotypes might be advantageous after all.

ASSUNTO(S)

visão de cores nutrição macaco callithrix penicillata animais do cerrado ecologia alimentar fisiologia

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