Cape Feather Coloration Signals Different Genotypes of the Most Polymorphic MHC Locus in Male Golden Pheasants (Chrysolophus pictus)

SIMPLE SUMMARY: Ornamental feather coloration in birds is deemed an honest signal of male quality, but is seldom embodied at the functional genetic level. The major histocompatibility complex is involved in the immune response, thereby affecting an organism’s fitness. Here, we tested the hypothesis that the coloration of the cape feather signals genetic quality in the male golden pheasant. We measured brightness, chroma, and hue as the main parameters to quantify color differences. Then, we investigated the genotypes of all major histocompatibility complex loci associated with adaptive immunity. The results showed that heterozygosity of the most polymorphic major histocompatibility complex locus was positively related with the brightness and chroma of cape feathers. Our study suggested that cape feather coloration might signal different genotypes of the most polymorphic major histocompatibility complex locus in male golden pheasants. ABSTRACT: Ornamental feather coloration is usually a reflection of male quality and plays an important role during courtship, whereas the essence of male quality at the genetic level is not well understood. Major histocompatibility complex (MHC)-based mate choice has been observed in various vertebrates. Here, we investigated the relationship between the coloration of cape feathers and the MHC genotypes in golden pheasants (Chrysolophus pictus). We found that feather coloration differed sharply among different individuals (brightness: 1827.20 ± 759.43, chroma: 1241.90 ± 468.21, hue: 0.46 ± 0.06). Heterozygous individuals at the most polymorphic MHC locus (IA2) had brighter feathers than homozygous individuals (Z = −2.853, p = 0.004) and were more saturated in color (Z = −2.853, p = 0.004). However, feather coloration was not related to other MHC loci or to overall genetic heterozygosity (p > 0.050). Our study suggested that coloration of cape feathers might signal IA2 genotypes in golden pheasants.