Examining the Molecular Basis of Coat Color in a Nocturnal Primate Family (Lorisidae)

Organisms use color for camouflage, sexual signaling, or as a warning sign of danger. Primates are one of the most vibrantly colored Orders of mammals. However, the genetics underlying their coat color are poorly known, limiting our ability to study molecular aspects of its evolution. The role of the melanocortin 1 receptor () in color evolution has been implicated in studies on rocket pocket mice (), toucans (Ramphastidae), and many domesticated animals. From these studies, we know that changes in result in a yellow/red or a brown/black morphology. Here, we investigate the evolution of in Lorisidae, a monophyletic nocturnal primate family, with some genera displaying high contrast variation in color patterns and other genera being monochromatic. Even more unique, the Lorisidae family has the only venomous primate: the slow loris (). Research has suggested that the contrasting coat patterns of slow lorises are aposematic signals for their venom. If so, we predict the in slow lorises will be under positive selection. In our study, we found that Lorisidae is under purifying selection ( = 0.0912). In Lorisidae there were a total of 75 variable nucleotides, 18 of which were nonsynonymous. Six of these nonsynonymous substitutions were found on the branch, which our reconstructions found to be the only member of Lorisidae that has predominantly lighter coat color; no substitutions were associated with . Our findings generate new insight into the genetics of pelage color and evolution among a unique group of nocturnal mammals and suggest putative underpinnings of monochromatic color evolution in the lineage.