BioArCh, Department of Archaeology, University of York, York, UK.
Department of Archaeology, Institute of History and Archaeology, University of Tartu, Tartu, Estonia.
Sci Rep. 2020 Oct 15;10(1):17340. doi: 10.1038/s41598-020-74415-z.
Native animal breeds constitute an invaluable pool of genetic resources in a changing environment. Discovering native breeds and safeguarding their genetic diversity through specific conservation programs is therefore of high importance. Endogenous retroviruses have proved to be a reliable genetic marker for studying the demographic history of sheep (Ovis aries). Previous research has revealed two migratory episodes of domesticated sheep from the Middle East to Europe. The first episode included predominantly 'primitive populations', while the second and most recent is hypothesised to have included sheep with markedly improved wool production. To examine whether the recently discovered Kihnu native sheep in Estonia have historically been part of the first migratory episode and to what extent they have preserved primitive genetic characters, we analysed retroviral insertions in 80 modern Kihnu sheep and 83 ancient sheep from the Bronze Age to Modern Period (850 BCE-1950 CE). We identified that the Kihnu sheep have preserved 'primitive', 'Nordic', and other 'ancient' retrotypes that were present both in archaeological and modern samples, confirming their shared ancestry and suggesting that contemporary Kihnu native sheep originate from the first migratory episode. However, over the course of history, there has been a gradual decrease in the frequency of primitive retrotypes. Furthermore, Kihnu sheep possessed several 'novel' retrotypes that were absent in archaeological individuals, but were shared with improvement breeds, suggesting recent crossing within the last two centuries. To preserve these ancient lineages, our results are being applied in the conservation program of the Kihnu Native Sheep Society.
本地动物品种在不断变化的环境中构成了宝贵的遗传资源库。因此，发现本地品种并通过特定的保护计划保护其遗传多样性非常重要。内源性逆转录病毒已被证明是研究绵羊（Ovis aries）种群历史的可靠遗传标记。先前的研究揭示了家养绵羊从中东向欧洲的两次迁徙事件。第一次包括主要的“原始种群”，而第二次也是最近的一次迁徙事件则假设包括了羊毛产量明显提高的绵羊。为了研究爱沙尼亚基赫努的本地绵羊是否在历史上一直是第一次迁徙事件的一部分，以及它们在多大程度上保留了原始的遗传特征，我们分析了 80 只现代基赫努绵羊和 83 只来自青铜时代到现代时期（公元前 850 年至公元 1950 年）的古代绵羊中的逆转录病毒插入。我们发现，基赫努绵羊保留了“原始”、“北欧”和其他“古老”的逆转录病毒原型，这些原型在考古和现代样本中都存在，证实了它们的共同祖先，并表明当代基赫努本地绵羊起源于第一次迁徙事件。然而，在历史的进程中，原始逆转录病毒原型的频率逐渐下降。此外，基赫努绵羊还拥有几种在考古个体中不存在的“新型”逆转录病毒原型，但与改良品种共享，表明最近在过去两个世纪内进行了杂交。为了保护这些古老的谱系，我们的研究结果正在基赫努本地绵羊协会的保护计划中得到应用。
