The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)


Trichromacy and red-hued pelages evolved independently in primates

CHRISTOPHER P. HEESY1, BRENDA J. BRADLEY2 and JASON M. KAMILAR1,3.

1Anatomy, Midwestern University, 2Anthropology, Yale University, 3School of Human Evolution and Social Change, Arizona State University

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In primates, reddish pelage and red hair ornaments have evolved independently many times. It is generally assumed that these red-coat phenotypes, like red skin phenotypes, play a role in socio-sexual signaling and thus evolved in tandem with conspecific color vision. This study examines the phylogenetic distribution of color vision and pelage coloration across the primates to ask: 1) did red pelage and trichromacy co-evolve; or 2) did trichromacy evolve first, and then subsequently red pelage evolved as an exaptation? We collected quantitative, color-corrected photographic color data for 142 museum research skins from 92 species representing 41 genera spanning all major primate lineages. We quantified the ratio of Red/Green values (from a RGB color model) at 20 anatomical landmarks. We also compiled data on color vision type (routine trichromatic, polymorphic, routine dichromatic, monochromatic) and data on variables that potentially covary with visual system and coloration, including activity pattern and body mass dimorphism. Analyzing the data with phylogenetic generalized least squares models, we found that the amount of red hair present in primates is associated with differences in visual systems, but not in the direction expected. Surprisingly, trichromatic primate species generally exhibited less red hair compared to red-green colorblind species. Thus, our results do not support the general assumption that color vision and red pelage coloration are a co-evolutionary product of socio-sexual signaling in primates. Our results have important implications for the evolution of primate coloration and visual systems.

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