海岛易危黄嘴白鹭MHC基因多样性及其进化适应机制的研究

The small populations of threatened species may cause the decline of both MHC gene diversity and adaptive immunity. In return, the less resistance to novel diseases may result in the extinction of the endangered species. In this study we investigated the diversity and evolutionary adaptation mechanism of major histocompatibility complex(MHC) genes in two diverged species of genus Egretta: the Chinese egret (Egretta eulophotes), which is an vulnerable species mainly breeding in Chinese archipelagoes, and its widespread relative breeding in both mainland and archipelagoes, the little egret (E. garzetta). On the basis of our separated genes of MHC I and MHC II in the Chinese egret, we will assay the diversities of MHC genes in both Chinese egret and little egret first in the world. We will compare the differences of MHC diversity between Chinese egret and little egret in same breeding archipelago for probing the evolution of MHC genes and the endangering mechanism of vulnerable Chinese egret in the level of specie.Then, we will compare the differences of MHC diversity among different archipelago breeding populations of Chinese egret, and between mainland breeding population and archipelago breeding population of little egret for clarifying the evolutionary adaptation of MHC genes to specific habitats in the level of population. Furthermore, we will examine the reproductive fitness consequences of MHC diversity and MHC genotypes, and analyze the association between MHC diversity or MHC genotypes and mate choice to test genetic mechanisms for mate choice. In this way, the evolutionary adaptation mechanism of MHC gene diversity will be clarified from natural selection and sexual selection, and the theories of evolutionary biology and conservation genetics for the MHC will be enriched.

受危物种由于种群小而可能引起MHC基因多样性及免疫力的下降，难以抵抗新疾病而发生灭绝。本项目以白鹭属两个亲缘物种，繁殖于沿海岛屿的易危物种黄嘴白鹭以及繁殖于大陆和海岛的广布物种白鹭为研究对象，在已获得黄嘴白鹭MHC I类和II类基因的基础上，测定完善国内外缺乏的黄嘴白鹭和白鹭的MHC基因多样性数据；通过比较同一海岛黄嘴白鹭与白鹭之间的MHC基因多样性差异，从物种水平上探讨MHC的进化以及黄嘴白鹭的受危机制；进而，比较黄嘴白鹭不同海岛繁殖种群之间、白鹭海岛与大陆不同繁殖种群之间的MHC基因多样性差异，从种群水平上阐明MHC基因对不同环境的进化适应；从个体水平上检查黄嘴白鹭MHC多样性、MHC基因型的繁殖适合度效果，分析MHC多样性、MHC基因型与配偶选择之间的关系以检验配偶选择的遗传学机制。由此从自然选择和性选择两方面阐明MHC基因多样性的进化适应机制，丰富MHC进化生物学和保护遗传学理论。

受危物种由于种群小而可能引起MHC基因多样性及免疫力的下降，难以抵抗新疾病而发生灭绝。本项目按照计划，以鹭科鸟类白鹭属两个亲缘物种，繁殖于沿海岛屿的易危物种黄嘴白鹭以及繁殖于大陆和海岛的广布物种白鹭为研究对象，率先测定完善国内外缺乏的黄嘴白鹭和白鹭的MHC基因多样性数据；通过分析比较黄嘴白鹭不同海岛繁殖种群之间、白鹭海岛与大陆不同繁殖种群之间的MHC基因多样性差异，分析黄嘴白鹭MHC基因多态性与寄生虫病抗性关联性，了解MHC基因对不同环境的进化适应，解释黄嘴白鹭 MHC基因多态性及其选择压力，探讨黄嘴白鹭MHC多样性、MHC基因型与繁殖力、生存力的相关性；由此阐明了MHC基因多样性的进化适应机制，丰富了MHC进化生物学和保护遗传学理论。同时，研究期间新建立了本项目研究所需要的一些分子生物学实验技术。本项目共培养3名博士生和5名硕士生毕业，发表具有本项目资助标注的学术论文9篇，其中第一标注8篇，第二标注1篇，SCI期刊论文7篇，项目研究成果超过预期指标。