The primate palette: The evolution of primate coloration

Abstract

Flip through The Pictorial Guide to the Living Primates1 and you will notice a striking yet generally underappreciated aspect of primate biology: primates are extremely colorful. Primate skin and pelage coloration were highlighted examples in Darwin's2 original discussions of sexual selection but, surprisingly, the topic has received little research attention since. Here we summarize the patterns of color variation observed across the primate order and examine the selective forces that might drive and maintain this aspect of primate phenotypic diversity. We discuss how primate color patterns might be adaptive for physiological function, crypsis, and communication. We also briefly summarize what is known about the genetic basis of primate pigmentation and argue that understanding the proximate mechanisms of primate coloration will be essential, not only for understanding the evolutionary forces shaping phenotypic variation, but also for clarifying primate taxonomies and conservation priorities.

Adaptive evolution of facial colour patterns in Neotropical primates

“…Facial colour pattern complexity, however, combines many discrete features that describe facial coloration as a whole, and thus integrates multiple signals that could function in conveying species identity. Biologists have proposed that social functions are the primary drivers of the evolution of primate facial colour patterns across species [1,18], and that variation within species is consistent with a behavioural drive model of evolution. This model predicts that behaviours initiate evolutionary shifts in morphology, physiology or ecology [19 -21].…”

“…Faces have evolved in many social lineages as complex and variable structures that must satisfy multiple functional demands [1][2][3]. Faces constitute complex phenotypes because they integrate numerous parts (eyes, nose, ears, patches of skin and hair, etc.)…”

“…Behavioural pressures have been invoked to explain the evolution of the facial musculature [22] and red skin [4,23] in non-human primates. Along with behavioural pressures, ecological pressures that drive adaptive evolution in mammalian coat colour, such as regulation of physiological processes and concealment from predators [1,2,24], may also drive the evolution of facial differences across species.…”

Has removal of excess cysteine led to the evolution of pheomelanin?

“…Pheomelanin-based color is also necessary to produce skin, coat and plumage patterns that confer camouflage or concealment, and in fact it has been suggested that the persistence of pheomelanin is mainly due to its camouflage and esthetic properties [10]. These properties may favor the evolution of pheomelanin, but certainly not all pheomelanin-based color traits act as quality signals [16], nor are they involved in concealment patterns [17]. Thus, these properties can only partly, at best, explain the evolutionary origin and the maintenance of pheomelanin.…”

Color in competition contexts in non-human animals

“…I concentrate on phenotypically plastic skin colour, and within species and within-individual differences, but note that also primates show wonderful coloured pelage (Bradley & Mundy, 2008;Gerald, 2003), including outstanding facial diversity which may function in species recognition (Santana, Lynch Alfaro, & Alfaro, 2012). I end with conclusions and future directions for the study of the influence of colour on the behaviour of non-human animals in contests for mates and resources.…”