Abstract
Pigmentation and color pattern exhibit tremendous diversity among animals. This reflects that they are ecologically important traits being exposed to various selective pressure of natural selection. In vertebrates, melanin-based pigmentation system has been modified during individual species evolution for use in survival strategies such as crypsis, aposematism, and sexual display. Understanding the generation of phenotypic diversity among animals requires defining the genetic changes involved. Coat color mutations in laboratory mice have served as a premier model for studying gene action in a variety of biological processes, leading to a wealth of information about genes involved in pigmentation. A deep understanding of mouse coat color genetics helps us study the molecular basis of pigmentation system in other vertebrates. Here, we introduce recent progress in our understanding of the molecular mechanism of melanin-based pigmentation in birds. Identification and characterization of genes encoded by feather pigmentation loci revealed that the melanin-based pigmentation system is highly conserved between birds and mammals. Furthermore, it is suggested that the intra-feather germ melanocortin system plays a crucial role in generating complicated color patterns in both individual feathers and plumage. Based on these findings, we hypothesize that changes in the regulation of expression of melanocortin system component genes partially contribute in generating phenotypic diversity in pigmentation between birds and mammals.
