Melanism variations of coat color in endemic macaques in Sulawesi Island, Indonesia

抄録

Coat coloration is one of greatest diverse phenotype in primates. The trait is often under selection because even small change in coloration can cause significant implication in camouflage, heat absorption, and communication. One notable form of coloration is melanism, which is a genetic trait that results in increased pigmentation and a darker coloration. Sulawesi macaques, seven endemic species located in Sulawesi Island, have rapidly speciated from the common ancestor and morphologically diversified. Distinct from other macaques, they exhibited distinct dark coat color but with difference in darkness and pattern between species. To understand the genetic mechanism of melanism variation, we firstly focus on both sequence and functional variation of MC1R, a gene regulating melanin synthesis and density. In total, we determined MC1R sequence of 46 saliva samples of five species of Sulawesi macaques, respectively. We found each species exhibited fixed amino acid substitutions. We further studied the cAMP induced ability of the MC1R in vitro. Each species MC1R exhibited specific functional performance, most of them have decreased MC1R basal activity but lead by different key residues, respectively. Further, we collected hair follicles from black and white body part of individual and determined RNA expression pattern. We found black samples has more similar expression pattern which are clustered in PCA analysis. While white samples showed large variation. Further analysis on expression pattern between black and white body part will promote the understanding of melanism variation.