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The current research focuses on color preference between red and green stimuli and manual laterality in the emperor tamarin (Saguinus imperator). Trichromacy in primates has been related to a foraging advantage allowing frugivore primates to distinguish ripe from unripe fruits as well to socio‐sexual communication, as trichromats would be advantaged in recognizing social and sexual signals. As warm colors can affect the emotive state of the subjects, leading to the activation of one hemisphere over the other (e.g., right hemisphere), this could lead to behavioral lateralization. Thus, studying of hand preference may be relevant when testing color preference. Nine adult zoo emperor tamarins were involved and the study aimed to investigate the preference between red, green, and white cones as well as manual laterality. Tamarins were provided with pairs of red‐green, red‐white, and green‐white combinations of cones. Ten 30‐min sessions per combination were carried out and data on the interaction with one of the two cones of each apparatus were collected to assess subjects' color preference. We also recorded the hand used by each subject during the interaction with cones of different colors and the position of the apparatus in respect to the tamarin. We found no preferences for colored versus white cones. Similarly, we reported no group‐level preferences within different color combinations, whereas individual‐level preferences were found when considering all choices. Finally, we found that red cones elicited a left‐hand preference, suggesting a right‐hemisphere involvement in the presence of red cones. Although we do not have genetic data on trichromat and dichromat females, the tendency to use the left hand when interacting with red stimuli provides further evidence that warm colors can influence the emotive state of the perceiver, affecting their manual lateralization. Highlights: This study investigated color preference (red vs. green) and manual lateralization in zoo emperor tamarins (Saguinus imperator).We collected data on preference between different combinations of red, green, and white cones.We also recorded the hand used for interacting with cones of different color.We found no preference for red, green, and white devices. Individual‐level preferences in both color choice and hand use were found.Emperor tamarins were more left‐handed when interacting with red stimuli, suggesting emotional implications in the evolution of trichromacy. [ABSTRACT FROM AUTHOR]

Howler monkeys (platyrrhini) have evolved routine trichromatic color vision independently from catarrhines, which presents an opportunity to test hypotheses concerning the adaptive value of distinguishing reddish from greenish hues. A longstanding hypothesis posits that trichromacy aids in the efficient detection of reddish‐ripe fruits, which could be an advantage for the detection of the nutritional content of the fruit, such as sugars. In the present study, we assessed fruit visual conspicuity and selection based on color and sucrose content by wild mantled howler monkeys (Alouatta palliata) on Agaltepec Island, Mexico. We used colorimetry to classify dietary fruits as cryptic (greenish) or conspicuous (reddish) against their background leaves. Species‐specific color models indicate that trichromatic howler monkeys should be more efficient in discriminating the conspicuous ripe fruits from leaves compared to detecting cryptic ripe fruits from leaves. We found howler monkeys consume more cryptic fruits compared to conspicuous fruits, and that they consume more unripe fruits than ripe fruits. The consumption (acceptance) of fruit was independent of sucrose content, and thus this disaccharide may not play an essential role in mantled howler food selection. Our findings suggest that routine trichromatic color vision may aid in the detection and discrimination of conspicuously colored fruits, but that the final decision whether to accept or reject a fruit probably involves the use of other senses in addition to vision. Research Highlights: Trichromacy may aid detection of conspicuous fruits, although selection of fruits likely involved other senses.Howler monkeys accepted cryptic fruits relatively more often compared to conspicuous fruits.Sucrose content did not play a clear role in the acceptance of fruits. [ABSTRACT FROM AUTHOR]

In contrast to the majority of primates, which exhibit dedicated diurnality or nocturnality, all species of Eulemur are cathemeral. Colour vision, in particular, is strongly affected by the spectral composition and intensity of ambient light, and the impact of activity period on the evolution of primate colour vision is actively debated., We studied three groups of wild brown lemurs ( Eulemur fulvus) in Ankarafantsika National Park, Madagascar, over a 1-year span. We also used non-invasive faecal DNA collection and analysis to study the opsin genes underlying the colour vision of 24 individuals. We quantified the colour and brightness of dietary fruits and modelled the chromaticity and discriminability of food objects to different visual phenotypes under daylight, twilight and moonlight conditions., We found that E. fulvus possesses routine dichromacy, unlike its congener E. flavifrons, for which polymorphic trichromacy has been reported. Our models suggest that dichromacy is well suited to the foraging ecology of E. fulvus. The performance of modelled dichromats and trichromats is comparable under nocturnal illuminants, and the luminance values of most diet items are detectable across light conditions. The trichromatic phenotype demonstrates a modest advantage under daylight conditions., Our results, taken together with reports of polymorphic trichromacy in E. flavifrons, suggest functional ecological variation in the visual system of the genus Eulemur. Interspecific phenotypic variation in the colour vision of a genus is both unexpected and instructive., Ecological differences between species of Eulemur could reveal thresholds for the origins of polymorphic trichromacy, which preceded the evolution of routine trichromatic vision in humans and other primates. [ABSTRACT FROM AUTHOR]

The color vision of most platyrrhine primates is determined by alleles at the polymorphic X-linked locus coding for the opsin responsible for the middle- to long-wavelength (M/L) cone photopigment. Females who are heterozygous at the locus have trichromatic vision, whereas homozygous females and all males are dichromatic. This study characterized the opsin alleles in a wild population of the socially monogamous platyrrhine monkey Callicebus brunneus (the brown titi monkey), a primate that an earlier study suggests may possess an unusual number of alleles at this locus and thus may be a subject of special interest in the study of primate color vision. Direct sequencing of regions of the M/L opsin gene using feces-, blood-, and saliva-derived DNA obtained from 14 individuals yielded evidence for the presence of three functionally distinct alleles, corresponding to the most common M/L photopigment variants inferred from a physiological study of cone spectral sensitivity in captive Callicebus. Am. J. Primatol. 73:189-196, 2011. © 2010 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

The remarkable variation in color vision both among and within primate species is receiving increasing attention from geneticists, psychophysicists, physiologists, and behavioral ecologists. It is known that color vision ability affects foraging behavior. Color vision is also likely to have implications for predation avoidance, social behavior, mate choice, and group dynamics, and should also influence the choice of stimuli for cognitive experiments. Therefore, understanding the color vision of a study species is important and of particular significance to scientists studying species with polymorphic color vision (most platyrrhines and some strepsirrhines). The papers in this issue were inspired by a symposium held during the 20th Congress of the International Primatological Society at Turin, Italy, in August 2004. The aim of the symposium was to bring together research from a range of disciplines, using recent methodological advances in molecular, modeling, and experimental techniques, to help elucidate the evolution, ecological importance, and distribution of color vision genotypes and phenotypes. The symposium achieved its aim, and as with most research in expanding disciplines, there are surprises and many questions still to be answered. Further advances will be made using a combination of different approaches involving analyses at the level of molecu1es, types of cell and neural networks, detailed and long-term field work, modeling, and carefully controlled experimentation. Am. J. Primatol. 67:393–398, 2005. © 2005 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Due to a middle- to long-wavelength-sensitive (M/LWS) cone opsin polymorphism, there is considerable phenotypic variation in the color vision of New World monkeys. Many females have trichromatic vision, whereas some females and all males have dichromatic vision. The selective pressures that maintain this polymorphism are unclear. In the present study we compared the performance of dichromats and trichromats in a discrimination task. We examined tri- and dichromatic individuals of two species: brown capuchin monkeys (Cebus apella) and long-tailed macaques (Macaca fascicularis). We also examined one protanomalous chimpanzee (Pan troglodytes). The subjects' task was to discriminate a circular pattern from other patterns in which textural elements differed in orientation and thickness from the background. After they were trained with stimuli of a single color, the subjects were presented with color-camouflaged stimuli with a green/red mosaic overlaid onto the pattern. The dichromatic monkeys and the protanomalous chimpanzee selected the correct stimulus under camouflaged conditions at rates significantly above chance levels, while the trichromats did not. These findings demonstrate that dichromatic nonhuman primates possess a superior visual ability to discriminate color-camouflaged stimuli, and that such an ability may confer selective advantages with respect to the detection of cryptic foods and/or predators. Am. J. Primatol. 67:425–436, 2005. © 2005 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Although most arguments explaining the predominance of polymorphic color vision in platyrrhine monkeys are linked to the advantage of trichromacy over dichromacy for foraging for ripe fruits, little information exists on the relationship between nutritional reward and performance in fruit detection with different types of color vision. The principal reward of most fruits is sugar, and thus it seems logical to investigate whether fruit coloration provides a long-distance sensory cue to primates that correlates with sugar content. Here we test the hypothesis that fruit detection performance via trichromatic color vision phenotypes provides better information regarding sugar concentration than dichromatic phenotypes (i.e., is a color vision phenotype with sufficient red-green (RG) differentiation necessary to “reveal” the concentration of major sugars in fruits?). Accordingly, we studied the fruit foraging behavior of Ateles geoffroyi by measuring both the reflectance spectra and the concentrations of major sugars in the consumed fruits. We modeled detection performance with different color phenotypes. Our results provide some support for the hypothesis. The yellow-blue (YB) color signal, which is the only one available to dichromats, was not significantly related to sugar concentration. The RG color vision signal, which is present only in trichromats, was significantly correlated with sugar content, but only when the latter was defined by glucose. There was in fact a consistent negative relationship between fruit detection performance and sucrose concentration, although this was not significant for the 430 nm and 550 nm phenotypes. The regular trichromatic phenotypes (430 nm, 533 nm, and 565 nm) showed higher correlations between fruit performance and glucose concentration than the other two trichromatic phenotypes. Our study documents a trichromatic foraging advantage in terms of fruit quality, and suggests that trichromatic color vision is advantageous over dichromatic color vision for detecting sugar-rich fruits. Am. J. Primatol. 67:411–423, 2005. © 2005 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

We present a quantitative means of assessing the conspicuousness of animal coats or other objects in terms of the color vision of each possible observer. We measured reflectance spectra from the fur and skin of many primate species in order to provide an objective survey of the possibilities of pelage coloration found in extant primates. We show that the orange coloration displayed by many platyrrhine and some strepsirhine primates, while being conspicuous to humans, would be cryptic amongst foliage to all males and many females of their own species. In relation to this finding, we briefly review what is known of the color vision of birds that prey on primates, and assess how conspicuous the orange pelage would be to these predators. Am. J. Primatol. 59:67–91, 2003. © 2003 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Several general of platyrrhine monkeys show significant polymorphism of color vision. By contrast, catarrhine monkeys have usually been assumed to have uniform trichromatic color vision. However, the evidential basis for this assumption is quite limited. To study this issue further, spectral sensitivity functions were obtained from vervet monkeys (Cercopithecus aethiops sabaeus) using the technique of electroretinographic flicker photometry. Results from a chromatic adaptation experiment indicated that each of the twelve subjects had two classes of cone pigment in the 540/640 nm portion of the spectrum. That result strongly suggests that this species has routine trichromatic color vision. Comparison of the spectral sensitivity functions obtained from vervets and from similarly-tested humans further indicates that the cone complements of the two species are very similar. Results from this investigation add further support to the idea that there are fundamental differences in the genetic mechanisms underlying color vision in platyrrhine and catarrhine monkeys. [ABSTRACT FROM AUTHOR]

Most species of New World primates have an unusual color vision pattern that can affect an individual's ability to detect food. Whereas males can only be dichromatic, females can be either dichromatic or trichromatic. Trichromats are expected to have an advantage in detecting conspicuous food whereas dichromats should be better at locating cryptic resources. Here we aimed to understand how color vision phenotype influences insect foraging by five groups of common marmosets living in a semiarid environment. We recorded insect predation events, noting morphotype and color of the captured insect, and the substrate from which it was captured. Color modeling suggested that, for all values of chromatic contrast resulting from comparing the measured insect–substrate pairs, trichromats outperformed dichromats. Females showed an overall higher insect capture rate than males. Females also showed a higher capture rate of conspicuous insects but there was no sex difference for the capture of cryptic insects. When we compared only dichromatic individuals there was no difference between sexes. These findings suggest that differences found in capture rate related not only to sex but also to visual polymorphism and that the latter is a crucial factor determining insect capture rate in common marmosets. Nevertheless, these results should be interpreted with caution because of the small number (three) of dichromat females and the unknown phenotype of the remaining females. Our results support the balancing selection hypothesis, suggesting that the advantage of one phenotype over the other may depend on environmental circumstances. This hypothesis has recently been considered as the most plausible for the maintenance of visual polymorphism in New World primates. Females of common marmosets showed an overall higher insect capture rate than males. Females also showed a higher capture rate of conspicuous insects but there was no sex difference for capture of cryptic insects. Dichromatic females and males, in turn, did not differ in insect capture rates. It appears that phenotype, but not sex, is the decisive factor that determines insect captures in these primates. It seems that trichromatic females have an advantage in insect foraging in semiarid environments. HIGHLIGHTS: Callithrix jacchus males and females capture similar rates of cryptic insects, whereas females capture more conspicuous insects.Among dichromats, insect captures do not differ.In semiarid environments, trichromats might have an advantage in insect foraging. [ABSTRACT FROM AUTHOR]