Plumage polymorphism and variation in the melanocortin-1 receptor gene in the Fuscous Flycatcher, Cnemotriccus fuscatus (Wied, 1831)

Abstract

We investigated the possible mechanisms behind the variation plumage color of the Fuscous Flycatcher, Cnemotriccus fuscatus, by sequencing the melanocortin-1 receptor (MC1R) gene, which has been associated with the variation in plumage coloration in birds. C. fuscatus is widely distributed in South America and includes seven subspecies, which differ in their plumage coloration. Here we tested the hypothesis that the variation in the MC1R gene explains the plumage polymorphism found in C. fuscatus. We sequenced the MC1R gene in six subspecies, representing two groups: group 1 (yellow morph), with three subspecies, C. f. duidae, C. f. fumosus, and C. f. fuscatus, and group 2 (white morph), with the remaining subspecies, C. f. bimaculatus, C. f. beniensis, and
C. f. fuscatior. The only variation we found among the C. fuscatus sequences were six non-synonymous substitutions from 22 variable sites, none of which were associated systematically with either plumage morph. The result of the neutrality test indicated that the polymorphism of the MC1R gene is not suggestive of signifi cant selection pressure. We conclude that variation in plumage coloration in C. fuscatus does not appear to be determined by the MC1R gene, and that it may be related to other loci or under the influence of environmental factors.