Sexual Selection and Trichromatic Color Vision in Primates: Statistical Support for the Preexisting‐Bias Hypothesis
Department of Biological Sciences, Ohio University, Athens, Ohio 45701, USA. The American Naturalist
(Impact Factor: 3.83).
08/2007; 170(1):10-20. DOI: 10.1086/518566
The evolution of trichromatic color vision in primates may improve foraging performance as well as intraspecific communication; however, the context in which color vision initially evolved is unknown. We statistically examined the hypothesis that trichromatic color vision in primates represents a preexisting bias for the evolution of red coloration (pelage and/or skin) through sexual selection. Our analyses show that trichromatic color vision evolved before red pelage and red skin, as well as before gregarious mating systems that would promote sexual selection for visual traits and other forms of intraspecific communication via red traits. We also determined that both red pelage and red skin were more likely to evolve in the presence of color vision and mating systems that promote sexual selection. These results provide statistical support for the hypothesis that trichromatic color vision in primates evolved in a context other than intraspecific communication with red traits, most likely foraging performance, but, once evolved, represented a preexisting bias that promoted the evolution of red traits through sexual selection.
Available from: Christoph Witzel
- "At the same time, particular effects for red have also been shown for colour preferences (Bornstein et al 1976; Franklin et al 2009; Maier et al 2009) and for human behaviour in general (Elliot and Niesta 2008; Elliot et al 2007; 2009; Hagemann et al 2008; Hill and Barton 2005). Therefore, we wonder whether our results are linked to the fact that saturated red colours have special communicative functions in the natural environment, such as indicating alert, nutritious fruits, and sexual dispositions (for a discussion see, eg, Fernandez and Morris 2007, page 10). Thirdly, we could observe that the memory colour effect for our stimuli appeared independently of their perceptual complexity and of the abstractness of their colour diagnostic characteristics. "
Available from: Arturo Tozzi
- "Blending refers to a " mental " space configuration in which elements of two input spaces are projected into a third space, the blend, which thus contains elements of both but is distinct from either one (Fauconnier 1997). If we figure this space not " mental " but " anatomical " , the blend turns into the inner receptor. "
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ABSTRACT: Recent advances in neuronal multisensory integration shed new light on questions concerning the functional architecture of mind and the nature of mental states. The neocortex is a sum of multisensory neurons that form extensive forward, backward and lateral connections and collect, via " inner " receptors, progressively more elaborate and converging inputs from unimodal and heteromodal areas. Our " plastic-connectionist " model provides a mechanicistic explanation to the issue of cognitive architecture, considering as well genetic constraints, phenotypic factors and dynamic interactions between organism and surrounding environment. The inner receptors integrate the inputs into a novel output which holds a semantic, rather than syntactic, content. The " theory of the inner receptors " , although reductionistic, takes into account the " cognitive " need of theoretical representational states and, supplying an empirical adequate description to conceptualist models, provides a neuroanatomical frame to cognitive semantics. Our senses do not exist in isolation of each other. Perception, cognition and motor control are integrated already at very early levels of processing, in a densely coupled system with multisensory interactions occurring at all temporal and spatial stages. Higher multisensory neurons are also able to re-evoke complex data also in absence of the original external stimuli, by comparing and integrating large amounts of semantic messages. KEY WORDS
Available from: Shoji Kawamura
- "Whether or not the anomalous trichromacy in howlers has any selective advantage, its presence indicates that uniform and normal trichromacy is not necessarily the optimum result of color vision evolution in wild primates. It is still an open question as to whether the difference between nonhuman catarrhines (uniform trichromacy) and platyrrhines (polymorphic color vision) is attributable to a 1) biogeographic differences among continents, e.g., the severity of seasonality, or a prevalence of drably colored fruits and asynchronous species, e.g., figs and palm fruits (Dominy et al.2003); 2) dietary variability, e.g., degree of dependence on insects, leaves, or colorful fruits and different food patch sizes (see Melin et al., 2013); 3) variation in social color signals (Changizi et al.2006; Fernandez and Morris 2007). Further population-level studies of the L/M opsin genes and field observations of visual behaviors of howlers are important for elucidating the evolutionary forces acting on color vision polymorphism in platyrrhine primates and routine and normal trichromacy in catarrhine primates. "
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ABSTRACT: Platyrrhine (New World) monkeys possess highly polymorphic color vision owing to allelic variation of the single-locus L/M opsin gene on the X chromosome. Most species consist of female trichromats and female and male dichromats. Howlers (genus Alouatta) are an exception; they are considered to be routinely trichromatic with L and M opsin genes juxtaposed on the X chromosome, as seen in catarrhine primates (Old World monkeys, apes, and humans). Yet it is not known whether trichromacy is invariable in howlers. We examined L/M opsin variation in wild howler populations in Costa Rica and Nicaragua (Alouatta palliata) and Belize (A. pigra), using fecal DNA. We surveyed exon 5 sequences (containing the diagnostic 277th and 285th residues for λmax) for 8 and 18 X chromosomes from Alouatta palliata and A. pigra, respectively. The wavelengths of maximal absorption (λmax) of the reconstituted L and M opsin photopigments were 564 nm and 532 nm, respectively, in both species. We found one M–L hybrid sequence with a recombinant 277/285 haplotype in Alouatta palliata and two L–M hybrid sequences in A. pigra. The λmax values of the reconstituted hybrid photopigments were in the range of 546~554 nm, which should result in trichromat phenotypes comparable to those found in other New World monkey species. Our finding of color vision variation due to high frequencies of L/M hybrid opsin genes in howlers challenges the current view that howlers are routine and uniform trichromats. These results deepen our understanding of the evolutionary significance of color vision polymorphisms and routine trichromacy and emphasize the need for further assessment of opsin gene variation as well as behavioral differences among subtypes of trichromacy.
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