Establishing the validity of domestication genes using DNA from ancient chickens
Establishing the validity of domestication genes using DNA from ancient chickens
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DOI：
10.1073/pnas.1308939110
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发表时间：
2014-04-29
影响因子：
11.1
通讯作者：
Larson, Greger
中科院分区：
文献类型：
--
作者：
Flink, Linus Girdland;Allen, Richard;Larson, Greger
现代家养动植物要经过人类的选择才能获得所需的表型特征和行为。对现代家养种群及其野生近亲的大规模遗传研究不仅揭示了特定表型性状的遗传机制，而且还允许识别候选驯化基因。我们对这些基因在驯化过程的初始阶段的重要性的理解，传统上是基于这样的假设，即可以基于现代基因数据集对过去做出强有力的推断。然而，越来越多来自古代DNA研究的证据表明，古代乃至历史上的人口往往与现代人口几乎没有相似之处。在这里，我们测试了在特定遗传座位上进行选择的时间背景，这些基因座位可以区分现代家鸡和它们现存的野生祖先。我们从12个欧洲考古遗址出土的80只古代鸡中提取了DNA，这些鸡的年代可以追溯到公元前280年到18世纪。我们针对三个不相关的遗传位点：线粒体控制区，一个与黄色皮肤相关的基因(β-胡萝卜素双加氧酶2)，以及一个被认为与光周期和生殖有关的驯化基因(促甲状腺激素受体，TSHR)。我们的结果揭示了这两个核基因的显著变异，这表明西方品种黄皮的共性和所有现代鸡的TSHR几乎固定只发生在过去的500年。此外，线粒体变异由于最近与外来品种的混合而增加。最后，我们强调了仅从现代基因数据推断过去的危险。
Modern domestic plants and animals are subject to human-driven selection for desired phenotypic traits and behavior. Large-scale genetic studies of modern domestic populations and their wild relatives have revealed not only the genetic mechanisms underlying specific phenotypic traits, but also allowed for the identification of candidate domestication genes. Our understanding of the importance of these genes during the initial stages of the domestication process traditionally rests on the assumption that robust inferences about the past can be made on the basis of modern genetic datasets. A growing body of evidence from ancient DNA studies, however, has revealed that ancient and even historic populations often bear little resemblance to their modern counterparts. Here, we test the temporal context of selection on specific genetic loci known to differentiate modern domestic chickens from their extant wild ancestors. We extracted DNA from 80 ancient chickens excavated from 12 European archaeological sites, dated from similar to 280 B.C. to the 18th century A.D. We targeted three unlinked genetic loci: the mitochondrial control region, a gene associated with yellow skin color (beta-carotene dioxygenase 2), and a putative domestication gene thought to be linked to photoperiod and reproduction (thyroid-stimulating hormone receptor, TSHR). Our results reveal significant variability in both nuclear genes, suggesting that the commonality of yellow skin in Western breeds and the near fixation of TSHR in all modern chickens took place only in the past 500 y. In addition, mitochondrial variation has increased as a result of recent admixture with exotic breeds. We conclude by emphasizing the perils of inferring the past from modern genetic data alone.