【作者】 吴孝兵；

【导师】 王义权； 周开亚；

【作者基本信息】 南京师范大学 ， 动物学， 2001， 博士

【摘要】 本文主要从保护遗传学和线粒体DNA全序列等2个方面对扬子鳄进行了研究。 扬子鳄是中国特有的珍稀爬行动物，野生鳄的数量稀少。为了保护这一物种，1979年建立了安徽省扬子鳄繁殖研究中心，这是目前世界上最大的扬子鳄饲养种群；此外，浙江长兴的村民也创建了一个扬子鳄养殖场。这2个饲养种群代表了中国扬子鳄种群遗传背景， 对1993～1998年安徽省扬子鳄繁殖研究中心内的亲代与子代鳄的繁殖情况进行的统计分析，表明：扬子鳄亲代卵的平均受精率为(75.66±2.29)％，子一代为(69.24±5.12)％；亲代产卵孵化幼鳄的平均畸形率为(0.30±0.20)％，而子一代产卵幼鳄平均畸形率为(1.85±0.95)％；经统计检验，卵的受精率和幼鳄的畸形率在亲代与子代间差异显著，但受精卵幼鳄孵化率在两代间差异不显著。通过饲养种群的家系和有效群体大小分析，作者认为造成子代鳄的繁殖率下降和畸形率上升的原因与扬子鳄低的遗传变异性有关。 目前对中国扬子鳄的遗传结构尚无人研究。本文通过RAPD方法研究了这2个主要饲养种群的遗传结构。从199个随机引物中筛选出35个引物，对43个个体(浙江长兴种群10个，安徽宣州种群33个)进行RAPD-PCR，其中有4个引物未能在所有43个个体中全部产生清晰的条带，31个引物的扩增产物用于分析。共获得193个清晰的可重复的扩增带，仅有21个条带为多态片段，占10.88％。43个个体的遗传距离的变动范围为0～0.0376，平均遗传距离为0.0104±0.0055SE。浙江饲养种群的平均遗传相似性为0.9948±0.0029 SE，高于安徽宣州饲养种群(0.9894+0.0055 SE)，浙江饲养种群中较低的遗传变异可能与奠基者效应有关。RAPD分析同时也表明，多态片段的平均显型频率为0.6656±0.3730SE。在多态片段中，有4条显型频率仅为0.0233的低频片段。2个饲养种群间的遗传距离仅为0.0009，结合多态片段的分布情况及43个个体的聚类分析表明，浙江长兴种群在遗传起源于安徽宣州种群。本研究还就扬子鳄的繁殖力降低与遗传变异间的关系及扬子鳄种群的遗传保护问题进行了讨论。 线粒体DNA基因组全序列作为研究动物系统发生的模型系统，虽然仍有一定的缺陷，但仍是生物学家研究系统进化最有力的工具，它是目前唯一可以提供基因组水更多还原

【Abstract】 The conservation genetics and the mitochondrial genome complete sequences of Chinese alligator （Alligator sinensis） were studied in the present paper.Chinese alligator is an endemic species in China. The likely extinction of it in the wild was recognised. To prevent this species becoming extinct, The Anhui Research Center of Chinese Alligator Reproduction （ARCCAR） was established in 1979, where the biggest captive population of Chinese alligator in the world （Xuanzhou subpopulation, XZSP） is kept. Another captive population （Changxin subpopulation, CXSP） was established by villagers in Changxin, Zhejiang Province.The reproduction rates of the captive population of Chinese alligator between 1993 and 1998 were analyzed. The results showed that the mean fertilization rate was （75.66±2.29）% in the parent generation and （69.24±5.12）% in the first filial generation. The difference between them was significant by t-test. The mean rate of malformed hatchling was （0.30±0.20）% in the parent generation and （1.85±0.95）% in F₁, which differed from each other significantly by t-test. However, there is no difference in the mean hatching rate between the two generations. Based on the analysis of pedigree and effective population size of the captive breeding population of Alligator sinensis in Xuanzhou, we consider that the decline of the reproduction rate and increase of malformed hatchling should be probably attributed to inbreeding. The genetic conservation research of Alligator sinensis was also proposed in the present paper.We examined the genetic variability in two captive subpopulations of the endangered Chinese alligator using RAPDs. Thirty-five random primers were selected among 199 random primers screened, and thirty-one primers were used in the analysis. A total of 193 reproducible RAPD fragments was scored among 43 individuals, of which 21 （10.88%） were polymorphic. The genetic distances between 43 individuals ranged from 0 to 0.0376 with average of 0 .0104±0.0055SE. The genetic similarity in CXSP （0.9948±0.0029SE） were higher than that in XZSP （0.9894±0.0055SE）. Founder effect is a possible explanation更多还原