【作者】 杨梅；

【导师】 杨光；

【作者基本信息】 南京师范大学 ， 遗传学， 2011， 硕士

【摘要】 本论文共包括三个部分：1.综述近年来中国鲸豚类的保护遗传学研究进展2.在之前线粒体,形态学测量及核微卫星工作的基础上,考虑到核基因内元资源丰富,所承受的进化压力小,可能存在更多的变异,所以我们通过分析144头江豚(Neophocaena phocaenoides)四个核基因内元的序列,进一步分析了中国水域江豚的遗传多样性,种群遗传结构及其系统地理格局。中国水域的三个江豚种群：南海种群,黄海种群和长江种群总体的核苷酸多样性和单元型多样型分别为0.5%与0.98,0.6%与0.99,0.5%与0.95。同时总体的Fst值(PTH:0.29,P<0.001；IFN1@:0.23,P<0.001；RDS:0.12,P<0.001；KIT:0.16,P<0.001)表明超过70%的核基因内元变异来自种群内。种群遗传结构分析表明,南海种群和长江种群的分化程度最高,其次是南海种群与黄海种群,而黄海种群与长江种群的分化程度最低。然而,并没有发现中国水域的江豚种群具有明显的系统地理格局。系统发生重建和中介网络图(median-joining network)分析均未能把来自不同地理种群或者不同水域的单元型区分为独立的进化枝。研究表明中国水域的三个江豚种群均具有高的单元型多样性和相对较低的核苷酸多样性,种群间存在高水平的分化。此外,还讨论了江豚,特别是长江江豚的保护管理对策。3.测定了来自鲸目的5个物种及海豹,河马,除河马外这些物种都具有相对简单消化系统,胃或盲肠中都缺少微生物消化。我们在鲸目动物及海豹的胰核糖核酸酶基因进化发现了正选择位点的存在。在无前肠发酵的动物中发现胰核糖核酸酶基因的适应性进化为日后进一步研究该基因的功能和进化提供了参考。更多还原

【Abstract】 This thesis includes three chapters:1. Some advances in the studies of cetaceans in Chinese waters were reviewed.2. Intraspecific genetic variation and phylogeographic pattern can provide insights into the population-level process responsible for differentiation and speciation and yield information useful for conservation purposes. In the present study, sequence variation at four nuclear introns which are respectively from the parathyroid hormone-like (PTH) gene, isolate Pdalzl692 interferon (IFN) gene, peripherin-like (RDS) gene, and tyrosine kinase receptor-like (KIT) gene, were examined to analyse genetic diversity and population, structure of the finless porpoise (Neophocaena phocaenoides) in Chinese waters. High among-population differentiation was revealed, with the analysis of molecular variance (AMOVA) showing a significant genetic structure between populations (PTH:FST=0.29, P< 0.001; IFN1@:FST=0.23, P<0.001; RDS:FST=0.12, P<0.001; KIT:FST=0.16, P<0.001). Although the common haplotypes accounted for more than one half of all samples examined, many haplotypes were found,to be restricted to specific population. The mismatch distributions, Tajima’s D and Fu’s test all suggested a recent colonization and population expansion in finless porpoises in Chinese waters. Some conservation considerations, with special reference to the conservation priority of the unique Yangtze freshwater population, were discussed.3. Pancreatic ribonuclease (RNASEl) is a digestive enzyme that has been recognized to be one of the most attractive model systems for molecular evolutionary studies. The contribution of RNASE1 gene duplication to the functional adaptation of digestive physiology in foregut-fermenting herbivores, mostly in ruminants, has been well documented. However, no one has ever done a comprehensive study on the cetacean, which are sister to the artiodactyls. Here, we sequenced this gene from 5 species of the cetacea, seal, hippopotamus,which all have a relatively simple digestive system and lack the microbial digestion in rumen or cecum, except hippopotamus. In contrast to our initial expectation bursts of positive selection have been shown to contribute the enigmatic diversification of these RNASE 1 genes in cetacean. The finding of the adaptive evolution of RNASE1 in animals without foregut fermentation provides another opportunity for further studies of the structure, function, and evolution of this gene, raising the possibility that new tissue specificity or other functions of RNASE1 genes might have developed in these species.更多还原