Molecular basis of the evolution of coat colour in primates
Primates show the greatest range of coat colour variation of any mammalian order. In addition to differences between species, coloration frequently varies across the body, between the sexes, and during an individual's growth and maturation. As a start among this bewildering array of variation, we are concentrating on closely related species or subspecies which have gross differences in the amount of red (phaeomelanin) and black (eumelanin) pigment, and which have little sexual dimorphism in colour. These include the lion tamarins (Leontopithecus - golden lion tamarin is illustrated left), howler monkeys (Alouatta), and certain langurs (Trachypithecus).
We are using a candidate gene approach to identify genes controlling the coloration differences. One such gene is the melanocortin-1-receptor (MC1R) gene, which controls the relative amount of eumelanin and phaeomelanin deposited in developing hairs. Results show that the MC1R does not have a general role in generating red-black pigmentation differences in closely related primates. However, the MC1R is under an unusual pattern of natural selection in lion tamarins and has probably played a role in their coat colour evolution. In particular, the relatively dark coat of the golden-headed lion tamarin may well be attributable to an unusual 8 amino acid deletion in the MC1R, which has been associated with melanism in a cat species, the jaguarundi.
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