Present-day domestic horses are immensely diverse in their maternally inherited mitochondrial DNA, yet they show very little variation on their paternally inherited Y chromosome. Although it has recently been shown that Y chromosomal diversity in domestic horses was higher at least until the Iron Age, when and why this diversity disappeared remain controversial questions. We genotyped 16 recently discovered Y chromosomal single-nucleotide polymorphisms in 96 ancient Eurasian stallions spanning the early domestication stages (Copper and Bronze Age) to the Middle Ages. Using this Y chromosomal time series, which covers nearly the entire history of horse domestication, we reveal how Y chromosomal diversity changed over time. Our results also show that the lack of multiple stallion lineages in the extant domestic population is caused by neither a founder effect nor random demographic effects but instead is the result of artificial selection-initially during the Iron Age by nomadic people from the Eurasian steppes and later during the Roman period. Moreover, the modern domestic haplotype probably derived from another, already advantageous, haplotype, most likely after the beginning of the domestication. In line with recent findings indicating that the Przewalski and domestic horse lineages remained connected by gene flow after they diverged about 45,000 years ago, we present evidence for Y chromosomal introgression of Przewalski horses into the gene pool of European domestic horses at least until medieval times.

中文翻译：

---

欧洲古代国内种马的遗传多样性下降。

如今的家养马在其母系遗传的线粒体DNA上差异巨大，但它们在其母本遗传的Y染色体上却显示出很小的变化。尽管最近已经表明，至少在铁器时代之前，家中马的Y染色体多样性较高，但是何时以及为什么这种多样性消失仍然是​​有争议的问题。我们对16个最近发现的Y染色体单核苷酸多态性进行了基因分型，这些基因多态性分布在96个古老的欧亚种马中，跨越了驯化的早期阶段（铜和青铜时代）到中世纪。使用几乎涵盖了马驯化整个历史的Y染色体时间序列，我们揭示了Y染色体多样性如何随时间变化。我们的结果还表明，现有家庭人口中缺乏多种种马血统既不是由创始人效应也不是由随机的人口统计学效应引起的，而是由铁器时代的欧亚草原和后来的游牧民族人为地进行了人工选择的结果。在罗马时期。此外，现代家庭单倍型可能源自另一个已经有利的单倍型，最有可能在驯化开始之后。与最近的发现表明Przewalski和家养马谱系在分化大约45,000年前后仍然通过基因流保持联系相一致，我们提出了Przewalski马的Y染色体基因渗入到欧洲家养马的基因库中的证据，至少直到中世纪。