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Whole mitochondrial genome sequencing of domestic horses reveals incorporation of extensive wild horse diversity during domestication

金佳添加于 2011-11-25 04:05 | 1867 次阅读 | 0 个评论

作者
Lippold S, Matzke NJ, Reissmann M, Hofreiter M
摘要
Background DNA target enrichment by micro-array capture combined with high throughput sequencing technologies provides the possibility to obtain large amounts of sequence data (e.g. whole mitochondrial DNA genomes) from multiple individuals at relatively low costs. Previously, whole mitochondrial genome data for domestic horses (Equus caballus) were limited to only a few specimens and only short parts of the mtDNA genome (especially the hypervariable region) were investigated for larger sample sets. Results In this study we investigated whole mitochondrial genomes of 59 domestic horses from 44 breeds and a single Przewalski horse (Equus przewalski) using a recently described multiplex micro-array capture approach. We found 473 variable positions within the domestic horses, 292 of which are parsimony-informative, providing a well resolved phylogenetic tree. Our divergence time estimate suggests that the mitochondrial genomes of modern horse breeds shared a common ancestor around 93,000 years ago and no later than 38,000 years ago. A Bayesian skyline plot reveals a significant population expansion beginning 6,000-8,000 years ago with an ongoing exponential growth until the present, similar to other domestic animal species. Our data further suggest that a large sample of wild horse diversity was incorporated into the domestic population; specifically, at least 46 of the mtDNA lineages observed in domestic horses (73%) already existed before the beginning of domestication about 5,000 years ago. Conclusion sOur study provides a window into the maternal origins of extant domestic horses and confirms that modern domestic breeds present a wide sample of the mtDNA diversity found in ancestral, now extinct, wild horse populations. The data obtained allow us to detect a population expansion event coinciding with the beginning of domestication and to estimate both the minimum number of female horses incorporated into the domestic gene pool and the time depth of the domestic horse mtDNA gene pool.
详细资料
- 文献种类:期刊
- 期刊名称: BMC Evolutionary Biology
- 期刊缩写: BMC Evolutionary Biology
- 期卷页: 2011年第11卷第1期 328页
- ISBN: 1471-2148
相关链接 DOI URL

金佳的文献笔记订阅

野生母马参与现代马群驯化过程

现代马在颜色和体型上均体现出多样性。图片提供：Monika Reissmann/Humboldt-University Berlin

如今，我们见到的马匹颜色不一，体型多样，但这功劳并不属于人类。

根据一项最新研究，家马的大多数特征很早就已存在，远远早于它们被人类驯养的时间。本月，研究人员在《BMC进化生物学》杂志网络版上撰文称，他们对45个品种的家马进行了完整的线粒体基因组分析，以此来寻找家马的驯化时间表，而线粒体DNA 被看成是细胞活动的能量“工厂”。

研究者发现，现代马大约出现在7000年前，这与此前的研究结果一致。数据还表明，所有家马的祖先出现在大约9.3万年前到3.8万年前，这比一些科学家认为的出现时间要晚得多，他们认为家马的祖先最早可追溯到一百万年以前。

另外，研究显示，超过70%的现代马谱系在被驯养前就已存在。这表明，大量的野生母马曾参与到了现代马群的驯化过程中。

马的驯化曾对人类社会产生过持久的影响。它们的出现增强了人类的流动性，促进了贸易，影响着人类的生活方式，同时深远地改变了战争。反过来，驯养过程中的人为选择也形成了马群的基因多样性，最终导致了我们所见到的现代马在表征和品种上的多样化。

此结果为研究现存家马的母体起源提供了一个窗口，同时证实，现代家马的品种在线粒体基因上呈现出广泛的多样性，而这些线粒体基因也存在于古代但现已灭绝的野马种群中。研究表明，现代马的大量出现与其驯养开始的时间一致，同时研究有助于预测被融合进现代家马基因库里的野生母马数量以及家马线粒体基因库的时间深度。（来源：科学时报闫洁）

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