Effect of the MC1R gene on sexual dimorphism in melanin-based colorations

Variants of the melanocortin-1 receptor (MC1R) gene result in abrupt, naturally selected colour morphs. These genetic variants may differentially affect sexual dimorphism if one morph is naturally selected in the two sexes but another morph is naturally or sexually selected only in one of the two sexes (e.g. to confer camouflage in reproductive females or confer mating advantage in males). Therefore, the balance between natural and sexual selections can differ between MC1R variants, as suggest studies showing interspecific correlations between sexual dimorphism and the rate of nonsynonymous vs. synonymous amino acid substitutions at the MC1R. Surprisingly, how MC1R is related to within-species sexual dimorphism, and thereby to sex-specific selection, has not yet been investigated. We tackled this issue in the barn owl (Tyto alba), a species showing pronounced variation in the degree of reddish pheomelanin-based coloration and in the number and size of black feather spots. We found that ...黑皮质素1受体（MC1R）基因的变异可产生受自然选择调控的突异形色型。若某一色型在两性中均受自然选择作用，而另一色型仅在单一性别中受自然选择或性选择作用（例如仅为繁殖雌性提供伪装优势，或为雄性赋予交配优势），则这类遗传变异可能对性二态性产生差异化影响。因此，自然选择与性选择之间的权衡可能因MC1R变异类型而异，正如相关研究所揭示的，性二态性与MC1R基因上非同义与同义氨基酸替换速率之间存在种间相关性。令人意外的是，目前尚未有研究探讨MC1R与种内性二态性的关联，以及其如何与性别特异性选择挂钩。本研究以仓鸮（Tyto alba）为研究对象，该物种的基于褐黑素的红棕色羽色深浅、黑色羽斑的数量与大小均存在显著变异。我们发现……