Since their domestication, sheep breeds have been a subject of artificial selection directed towards production of wool, meat and milk as well as natural selection associated with regional climates and nutritional conditions. These selection pressures created a large diversity of sheep breeds and the opportunity to study their genetic differentiation. Despite the existence of several studies on genetic variation and selection signatures in sheep, information on the genetic background and variability of local sheep populations, especially on a genome wide-level, is still incomplete. This is mostly due to the large number of local sheep breeds and populations in existence. Several of these populations are under conservative breeding because of their largely primitive character, which is not suitable for the modern intensive animal production. In this study we analysed population parameters and quantified genetic differentiation among seven Polish conserved sheep breeds or local sheep populations, namely: Black-headed (BH; n=104), Polish Merino of coloured variety (MPC; n=59), ‘Old type’ Merino (MPOT; n=50), Polish Mountain Sheep (PMS; n=103), Świniarka (SW; n=100), Uhruska (UHR; n=69) and Wrzosówka (WRZ; n=90). The breeds represent mainly multipurpose production type with the emphasize on meat, wool and skin. Based on the data from OvineSNP50 BeadChip array (Illumina), we found that the genetic structures of the populations are not heavily affected, despite the bottlenecks in their recent breeding history. The only exception seems to be the SW breed in which we found very low effective population size (30.7) and high level of genomic inbreeding (17% as shown by F_ROH). Average MAF across breeds was high and ranged from 0.285 in MPC to 0.297 in PMS. The average observed heterozygosity per breed ranged from 0.378 in SW to 0.398 in UHR. The admixture patterns analysis showed that the analysed breeds have distinct genetic profiles with clear signs of common origin and admixture, similar to other worldwide sheep populations. By using F_ST statistics we also identified loci of the genome with the strongest divergence between the analysed breeds, presumably responsible for the fixed genetic differences among them which were created by artificial selection. The most pronounced of these results was selection signal at the locus of RXFP2 gene which is responsible for horn size/type in sheep. This analysis also allowed for genomic localization of genetic differences between the analysed breeds, providing a basis for further studies aimed at identification of sources of genetic variation in these sheep breeds.

自驯化以来，绵羊品种一直是人工选择的主题，旨在生产羊毛、肉类和牛奶，以及与区域气候和营养条件相关的自然选择。这些选择压力创造了大量绵羊品种和研究其遗传分化的机会。尽管存在一些关于绵羊遗传变异和选择特征的研究，但关于当地绵羊种群遗传背景和变异性的信息，尤其是在全基因组水平上，仍然不完整。这主要是由于存在大量当地绵羊品种和种群。其中一些种群由于其基本原始特征而处于保守繁殖之下，不适合现代集约化动物生产。在这项研究中，我们分析了七个波兰保守绵羊品种或当地绵羊种群之间的种群参数和量化遗传差异，即：黑头羊（BH；n=104）、有色品种的波兰美利奴羊（MPC；n=59）、“老类型'美利奴羊（MPOT；n=50）、波兰山羊（PMS；n=103）、Świniarka（SW；n=100）、Uhruska（UHR；n=69）和 Wrzosówka（WRZ；n=90）。这些品种主要代表多用途生产类型，强调肉、羊毛和皮。基于来自 OvineSNP50 BeadChip 阵列 (Illumina) 的数据，我们发现种群的遗传结构并未受到严重影响，尽管它们最近的育种历史存在瓶颈。唯一的例外似乎是 SW 品种，其中我们发现有效种群规模非常低 (30.7) 和高水平的基因组近亲繁殖（如 F 所示为 17%_罗）。不同品种的平均 MAF 很高，范围从 MPC 的 0.285 到 PMS 的 0.297。每个品种观察到的平均杂合度从 SW 的 0.378 到 UHR 的 0.398 不等。混合模式分析表明，所分析的品种具有不同的遗传谱，具有明显的共同起源和混合迹象，类似于世界范围内的其他绵羊种群。通过使用 F _ST统计，我们还确定了分析品种之间差异最大的基因组位点，这可能是人工选择造成的固定遗传差异的原因。这些结果中最显着的是RXFP2基因座的选择信号负责羊角大小/类型的基因。该分析还允许对所分析品种之间的遗传差异进行基因组定位，为旨在确定这些绵羊品种遗传变异来源的进一步研究奠定基础。