CAS Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences (CAS), Beijing 100101, China.
College of Life Sciences, University of Chinese Academy of Sciences (UCAS), Beijing 100049, China.
Genes (Basel). 2023 Oct 23;14(10):1977. doi: 10.3390/genes14101977.
In theoretical biology, a prevailing hypothesis posits a profound interconnection between effective population size (), genetic diversity, inbreeding, and genetic load. The domestication and improvement processes are believed to be pivotal in diminishing genetic diversity while elevating levels of inbreeding and increasing genetic load. In this study, we performed a whole genome analysis to quantity genetic diversity, inbreeding, and genetic load across seven wild species and five domesticated sheep breeds. Our research demonstrates that the genetic load and diversity of species in the genus have no discernible impact on recent , and three species within the subgenus tend to carry a higher genetic load and lower genetic diversity patterns. The results coincide with these species' dramatic decline in population sizes within the subgenus ~80-250 thousand years ago. European mouflon presented with the lowest , lower genetic diversity, and higher individual inbreeding coefficient but a lower genetic load (missense and LoF). This suggests that the small of European mouflon could reduce harmful mutations compared to other species within the genus . We showed lower genetic diversity in domesticated sheep than in Asiatic mouflon, but counterintuitive patterns of genetic load, i.e., lower weak genetic load (missense mutation) and no significant difference in strong genetic load (LoF mutation) between domestic sheep and Asiatic mouflon. These findings reveal that the "cost of domestication" during domestication and improvement processes reduced genetic diversity and purified weak genetic load more efficiently than wild species.
在理论生物学中，一个流行的假设假设有效种群大小（）、遗传多样性、近交和遗传负荷之间存在深刻的相互关系。驯化和改良过程被认为是降低遗传多样性、提高近交程度和增加遗传负荷的关键。在这项研究中，我们对七个野生种和五个家养绵羊品种进行了全基因组分析，以量化遗传多样性、近交和遗传负荷。我们的研究表明，属种的遗传负荷和多样性对最近的没有明显影响，亚属中的三个种倾向于携带更高的遗传负荷和更低的遗传多样性模式。这些结果与这些物种在亚属中种群数量的急剧下降相一致~80-250 千年前。欧洲盘羊表现出最低的遗传多样性和更高的个体近交系数，但遗传负荷较低（错义突变和 LoF）。这表明，欧洲盘羊的小种群数量可能比属中的其他物种减少有害突变。我们显示，家养绵羊的遗传多样性低于亚洲盘羊，但遗传负荷的模式却出人意料，即家养绵羊的弱遗传负荷（错义突变）较低，而强遗传负荷（LoF 突变）与亚洲盘羊没有显著差异。这些发现表明，在驯化和改良过程中，“驯化成本”降低了遗传多样性，并比野生种更有效地纯化了弱遗传负荷。
