In the last decade, several studies aimed at dissecting the genetic architecture of local small ruminant breeds to discover which variations are involved in the process of adaptation to environmental conditions, a topic that has acquired priority due to climate change. Considering that traditional breeds are a reservoir of such important genetic variation, improving the current knowledge about their genetic diversity and origin is the first step forward in designing sound conservation guidelines. The genetic composition of North-Western European archetypical goat breeds is still poorly exploited. In this study we aimed to fill this gap investigating goat breeds across Ireland and Scandinavia, including also some other potential continental sources of introgression. The PCA and Admixture analyses suggest a well-defined cluster that includes Norwegian and Swedish breeds, while the crossbred Danish landrace is far apart, and there appears to be a close relationship between the Irish and Saanen goats. In addition, both graph representation of historical relationships among populations and f4-ratio statistics suggest a certain degree of gene flow between the Norse and Atlantic landraces. Furthermore, we identify signs of ancient admixture events of Scandinavian origin in the Irish and in the Icelandic goats. The time when these migrations, and consequently the introgression, of Scandinavian-like alleles occurred, can be traced back to the Viking colonisation of these two isles during the Viking Age (793-1066 CE). The demographic analysis indicates a complicated history of these traditional breeds with signatures of bottleneck, inbreeding and crossbreeding with the improved breeds. Despite these recent demographic changes and the historical genetic background shaped by centuries of human-mediated gene flow, most of them maintained their genetic identity, becoming an irreplaceable genetic resource as well as a cultural heritage.

在过去的十年中，几项研究旨在剖析当地小型反刍动物品种的遗传结构，以发现哪些变异参与了适应环境条件的过程，这一主题因气候变化而受到优先关注。考虑到传统品种是如此重要的遗传变异的储存库，提高目前对其遗传多样性和起源的了解是设计健全的保护指南的第一步。西北欧典型山羊品种的遗传组成仍未得到充分利用。在这项研究中，我们旨在填补这一空白，调查爱尔兰和斯堪的纳维亚半岛的山羊品种，包括其他一些潜在的大陆渗入来源。 PCA 和混合分析表明，一个明确的集群包括挪威和瑞典品种，而杂交的丹麦地方品种相距甚远，而爱尔兰山羊和萨能山羊之间似乎存在密切的关系。此外，种群之间历史关系的图表表示和 f4 比率统计都表明挪威和大西洋地方品种之间存在一定程度的基因流动。此外，我们还发现了爱尔兰山羊和冰岛山羊中起源于斯堪的纳维亚的古代混合事件的迹象。这些迁移以及由此产生的类似斯堪的纳维亚等位基因的基因渗入的时间可以追溯到维京时代（公元 793-1066 年）维京人对这两个岛屿的殖民统治。人口统计分析表明，这些传统品种有着复杂的历史，具有瓶颈、近亲繁殖和与改良品种杂交的特征。 尽管最近发生了这些人口变化，以及几个世纪以来人类介导的基因流塑造的历史遗传背景，但他们中的大多数仍然保持着自己的遗传身份，成为不可替代的遗传资源和文化遗产。