The molecular basis of an avian plumage polymorphism in the wild:: A melanocortin-1-receptor point mutation is perfectly associated with the melanic plumage morph of the bananaquit, Coereba flaveola
The molecular basis of an avian plumage polymorphism in the wild:: A melanocortin-1-receptor point mutation is perfectly associated with the melanic plumage morph of the bananaquit, Coereba flaveola
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DOI：
10.1016/s0960-9822(01)00158-0
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发表时间：
2001-04-17
期刊：
影响因子：
9.2
通讯作者：
Mundy, NI
中科院分区：
文献类型：
--
作者：
Theron, E;Hawkins, K;Mundy, NI
背景资料：进化依赖于自然选择对表型变异的作用，但在脊椎动物的自然种群中负责表型变异的基因却很少为人所知。羽毛颜色变异的分子遗传基础在任何野生鸟类中都没有被描述过。Bananaquits（Coereba flaveola）是小型雀形目鸟类，有两种主要的羽毛变体，一种是广泛分布的黄色变体，背部和胸部都是黑色的，而另一种几乎是黑色的。这种颜色差异的候选基因是黑皮质素-1受体（MC 1 R），黑色素合成的关键调节器在羽毛melanocytes.Results：我们测序的MC 1 R基因从四个加勒比海人口的bananaquit;两个人口的黄色形态和两个人口包含的黄色形态和黑色形态。一个点突变，导致谷氨酸与赖氨酸的替代是目前在MC 1 R基因的至少一个等位基因在所有的黑色鸟类，是不存在的，在所有的黄色形态鸟类。这种替代可能会导致颜色的变化，因为相同的替代是负责在国内鸡和小鼠的黑化。MC IR单倍型之间的进化关系表明，格林纳达和圣文森特的黑色素等位基因有一个单一的起源。黄色单倍型中非同义替换的低发生率表明它们一直处于稳定选择之下，而对黑色单倍型不存在强选择约束。我们得出结论，MC 1 R的突变是野生鸟类种群中羽毛多态性的原因，格林纳达和圣文森特巴纳奎特种群中的黑色素MC 1 R等位基因具有单一的进化，来自黄色等位基因。
Background: Evolution depends on natural selection acting on phenotypic variation, but the genes responsible for phenotypic variation in natural populations of vertebrates are rarely known. The molecular genetic basis for plumage color variation has not been described in any wild bird. Bananaquits (Coereba flaveola) are small passerine birds that occur as two main plumage variants, a widespread yellow morph with dark back and yellow breast and a virtually all black melanic morph. A candidate gene for this color difference is the melanocortin-1 receptor (MC1R), a key regulator of melanin synthesis in feather melanocytes.Results: We sequenced the MC1R gene from four Caribbean populations of the bananaquit; two populations of the yellow morph and two populations containing both the yellow morph and the melanic morph. A point mutation resulting in the replacement of glutamate with lysine was present in at least one allele of the MC1R gene in all melanic birds and was absent in all yellow morph birds. This substitution probably causes the color variation, as the same substitution is responsible for melanism in domestic chickens and mice. The evolutionary relationships among the MC IR haplotypes show that the melanic alleles on Grenada and St. Vincent had a single origin. The low prevalence of nonsynonymous substitutions among yellow haplotypes suggests that they have been under stabilizing selection, whereas strong selective constraint on melanic haplotypes is absent.Conclusions: We conclude that a mutation in the MC1R is responsible for the plumage polymorphism in a wild bird population and that the melanic MC1R alleles in Grenada and St. Vincent bananaquit populations have a single evolutionary, origin from a yellow allele.