| Description |
Feather pigmentation in the domesticated rock pigeon, Columba livia, is stunningly diverse. Plumage pigmentation in this, and other, columbid (pigeon and dove) species plays an important role in mate choice and thus is a driving factor in the process of sexual selection. To study the genetic basis of plumage color variation we examined variation in the pigmentation gene Mc1r (melanocortin-1 receptor). Mc1r sits on the surface of melanocytes and regulates a cyclic adenosine monophosphate (cAMP)- dependent signal transduction pathway that leads to the production of eumelanin (black to brown pigment) and pheomelanin (red to yellow pigment). This gene is highly conserved across vertebrate taxa and mutations within Mc1r are known to be associated with variation in the coloration of many species. We sequenced the coding region of Mc1r in 118 pigeons with distinct pigmentation phenotypes to uncover potential associations between pigeon color phenotype and polymorphism within Mc1r. We discovered a nonsynonymous mutation in pigeons, Val85Met, which is known to be perfectly associated with plumage color variation in another avian species, the lesser snow goose (Anser Chen caerulescens). With this information in mind we genotyped an additional 109 pigeons at this locus using a TaqMan assay. Our final pool of 217 pigeons was segregating the derived Met85 allele at a frequency of 10.94%. Chi-squared analyses of different pigmentation phenotypes indicate that there is no statistically significant association between pigeon plumage pigmentation and the Val85Met mutation. This conclusion points to other causative genes (e.g. Agouti), regulatory mutations, or complex interactions between genes as being the driving force behind the variation in domesticated pigeon plumage pigmentation. |
