March 25, 2004

  • Final draft + title


    MC1R variation is not linked to small-scale melanic plumage patterns in two passerine birds.

    Studies that link molecular variation in the melanocortin-1 receptor (MC1R) gene with total body melanism in vertebrates have recently become models for understanding the molecular basis of adaptive variation in natural populations. We examined whether MC1R variation can be correlated with small-scale melanic plumage patterns by comparing  MC1R sequences in melanic and non-melanic subspecies of two passerine birds: Swamp Sparrows (Melospiza georgiana) and Grasshopper Sparrows (Ammodramus savannarum). The levels of variation found in each species were typical of passerine birds but no fixed nonsysnonymous substitutions were found that correlated with plumage differences in either species. We conclude that variation in the coding region of the MC1R gene is not responsible for these small-scale pigment pattern variations and that variation in this gene may only determine rare instances of large-scale, whole body melanism in birds and not more common small-scale patterns.