MHC影响秦岭川金丝猴配偶选择的分子机制

A mating system is a way in which a group is structured in relation to sexual behaviour. It reflect the compromise between female and male strategies to gain access to mates, food and other resources that they and their offsping need to survive. Mating systems for primates are often affected by their social organizations. However, despite social structure of a population plays an important role, it often deviates from its mating system. The basic social unit of Golden snub-nosed monkey is polygynous one-male unit (OMU). However, both behavioral observation and genetic data suggest that their mating system is polygamous. As the core aspect of mating system, knowledge on mate choice is essential for obtaining a full picture of mating patterns in a population, which is important for understanding its mating systems. Genes in the major histocompatibility complex (MHC), best known for their role in immune recognition, are also involved in modulating mate choice. MHC-based disassortative mating were detected in many different species. This project will isolate MHC class II genes of Golden snub-nosed monkey using magnetic bead hybridization method. We will investigate the genetic variations of these loci using locus-specific single-strand conformation polymorphism (SSCP) genotyping coupled with sequencing techniques. We will determine the selection pressures on MHC genes of Golden snub-nosed monkey. Furthmore, integrating data on genotype and behavioral observation, this project aims to: 1) reveal the relativity between MHC genotype and extra-unit copulation, as well as MHC genotype and female transfer; 2) investigate the effect of MHC-based disassortative mating on mate choice of this species; 3) understand the strategies of this species maintaining their genetic variation through mate choice. These will enable us to further understand the mating systems of primates and contribute in conservation of this endanger species.

动物的婚配制度与社会结构密切相关，然而表象的社会婚配关系常与其实际的遗传婚配关系不匹配，配偶选择策略可能受到更为复杂的分子机制左右。因此，探讨配偶选择的分子机制，对理解物种婚配制度的形成具有重要的理论意义。研究发现川金丝猴的社会婚配关系是一夫多妻制，然而遗传婚配关系却是混交制。金丝猴在交配活动中，雌雄两性均存在配偶选择现象，但其分子机制尚不明确。大量研究表明，MHC与配偶选择密切相关，基于MHC的异型交配在不同物种中广泛存在。本项目以秦岭川金丝猴为研究对象，通过探针杂交法分离MHC II类基因，利用基因分型引物调查群体遗传变异情况，明确MHC基因的多态性模式及其成因。在此基础上，结合行为学数据和个体间亲缘关系，分析MHC基因型对配偶选择倾向的影响，从分子水平上探讨该物种通过配偶选择维持种群遗传多样性的策略，阐明川金丝猴配偶选择的分子机制，为人工繁育金丝猴这一濒危物种提供科学的指导。

经过长期的野外跟踪观察，我们积累了大量研究群中个体间交配关系，生育记录，单元结构以及配偶变化的数据，并对相关个体进行了遗传学样本的采集。利用MHC基因分型引物对配偶选择相关个体进行了基因分型，结果发现尽管在过去400年间经历了严重的瓶颈效应，秦岭川金丝猴仍保留了一定的适应性变异，遗传多样性水平与同域分布的大熊猫相当。系统进化分析和选择压力分析表明，跨物种进化和正选择在川金丝猴的MHC位点多态性的形成中具有重要作用。配偶选择机制分析并未发现异型交配的直接证据，但在DQB，DPB位点上存在的杂合子优势现象暗示了异型交配的存在；与之形成鲜明对比的DQA位点，则呈现出纯合子优势（雌性）的同型交配；DRB的两个基因座位上，拥有3条等位基因的个体具有更高的繁殖成功率，表明适度的遗传变异而不是最大化的遗传变异更有利于繁殖的成功。