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Abstract：
Genetic diversity is an essential indicator that echoes the natural selection and environmental adaptation of a species. Isolated small populations are vulnerable to genetic drift, inbreeding, and limited gene flow; thus, assessing their genetic diversity is critical in conservation. In this study, we studied the genetic diversity of black-and-white snub-nosed monkeys (Rhinopithecus bieti) using neutral microsatellites and five adaptive major histocompatibility complex (MHC) genes. Two DQA1 alleles, two DQB1 alleles, two DRB1 alleles, two DRB5 alleles, and three DPB1 alleles were isolated from a population. The results indicate that neutral microsatellites demonstrate a high degree of heterozygosity and polymorphism, while adaptive MHC genes display a high degree of heterozygosity and moderate polymorphism. The results also show that balancing selection has prominently influenced the MHC diversity of the species during evolution: (1) significant positive selection is identified at several amino acid sites (primarily at and near antigen-binding sites) of the DRB1, DRB5, and DQB1 genes; (2) phylogenetic analyses display the patterns of trans-species evolution for all MHC loci. This study provides valuable genetic diversity insights into black-and-white snub-nosed monkeys, which dwell at the highest altitude and have experienced the harshest environmental selection of all primates globally since the Pleistocene. Such results provide valuable scientific evidence and a reference for making or amending conservation strategies for this endangered primate species.
摘要：
遗传多样性是反映物种自然选择和环境适应的重要指标。孤立的小种群容易受到遗传漂移的影响，近亲繁殖,和有限的基因流动；因此，评估它们的遗传多样性对保护至关重要。在这项研究中,我们使用中性微卫星和五个适应性主要组织相容性复合体（MHC）基因研究了黑白金丝猴（Rhinopithecusbieti）的遗传多样性。两个DQA1等位基因，两个DQB1等位基因，两个DRB1等位基因，两个DRB5等位基因，从一个种群中分离出三个DPB1等位基因。结果表明，中性微卫星表现出高度的杂合性和多态性，而适应性MHC基因表现出高度杂合性和中度多态性。结果还表明，平衡选择在进化过程中显著影响了物种的MHC多样性：（1）在DRB1，DRB5和DQB1基因的几个氨基酸位点（主要在抗原结合位点及其附近）发现了显着的正选择；（2）系统发育分析显示了所有MHC基因座的跨物种进化模式。这项研究为黑白金丝猴提供了有价值的遗传多样性见解，自更新世以来，它们居住在最高海拔，经历了全球所有灵长类动物中最恶劣的环境选择。这些结果为制定或修改这种濒危灵长类动物的保护策略提供了宝贵的科学证据和参考。
