中国近海两种水母的遗传多样性和种群遗传结构研究
其他题名Genetic Diversity and Population Genetic Structure of Two Jellyfish Species in Chinese Coastal Waters
刘青青
学位类型硕士
导师董志军
2018-05-22
培养单位中国科学院烟台海岸带研究所
学位授予单位中国科学院大学
学位授予地点中国科学院烟台海岸带研究所
学位名称工学硕士
学位专业生物工程
关键词遗传多样性遗传结构海月水母钩手水母线粒体DNAGenetic DiversityGenetic StructureAurelia coeruleaGonionemus vertensMitochondrial DNA
摘要自20世纪90年代中后期起，我国东海及黄渤海海域水母暴发事件频繁发生，水母暴发不仅影响生态系统的结构和功能，同时对海洋渔业、沿海旅游业以及人身安全造成极大的威胁，引起政府及科研工作者的广泛关注。海洋水母类的身体外部结构简单，缺少甄别种群或亚种群的形态特征，因此无法从形态学角度判断不同海域的暴发水母是否为同一种群或亚种群。在此情况下，对来自不同海域的水母进行遗传多样性和遗传结构研究，以明晰其分类从属地位和种群遗传特征。本文基于线粒体16S rRNA基因片段对海月水母、基于线粒体COI和16S rRNA基因片段对钩手水母进行种群遗传特征分析。主要研究工作与结果如下：一、基于线粒体16S rRNA基因片段的海月水母种群遗传学分析海月水母在我国黄渤海海域广泛分布，是水母暴发常见种类之一，在海参养殖池和近岸海域均发生暴发现象。对采自黄渤海近岸海参养殖池中的4个海月水母碟状幼体群体和近岸海域4个海月水母成体群体共计8个地理群体进行了种群遗传学研究。本研究共获得166条海月水母16S rRNA基因部分序列，通过BLASTn比对，发现黄渤海近岸海参养殖池内的海月水母碟状幼体均为Aurelia coerulea（Aurelia sp.1），与近岸海域的海月水母为同一亚种。海月水母总群体的单倍型多样性和核苷酸多样性分别为0.686 ± 0.032（Hd > 0.5）和（0.329 ± 0.019）%（π < 0.5%），海月水母总群体Fu’s Fs值和Tajima’s D值的结果表明其历史上经历了明显的群体扩张事件。遗传分化指数结果显示，潍坊海域的海月水母成体群体与青岛海域的海月水母成体，与东营、乐亭和青岛海域的海月水母碟状幼体群体间存在较大的遗传分化，且群体间的基因流受限（Fst > 0.25；P < 0.05；Nm < 1）。青岛海域的海月水母成体和碟状幼体、荣成海域的海月水母成体和碟状幼体以及曹妃甸海域的海月水母成体和乐亭海域的海月水母碟状幼体群体间无显著的遗传分化，由于海参养殖池与近岸海域连通，无明显的地理隔离，海参养殖池中的海月水母碟状幼体与近岸海域的海月水母成体为同一遗传群体。系统发育分析结果显示，各单倍型演化关系与地理种群的分布无显著的对应关系，海月水母群体间无明显的系统地理结构。不同地理群体遗传分析的结果有助于分析海月水母的迁移扩散，对判断不同海域的暴发水母是否为同一种群具有重要意义。二、基于线粒体COI和16S rRNA基因片段的钩手水母种群遗传学研究钩手水母为大西洋和太平洋广布种，是我国习见的有毒水母种类之一。本文共获得104条钩手水母线粒体COI基因部分序列，并结合GenBank上182条COI同源序列进行序列变异分析。钩手水母总群体的单倍型多样性和遗传多样性分别为0.743 ± 0.012（Hd > 0.5）和（1.046 ± 0.097）%（π > 0.5%），表明钩手水母总群体是由一个稳定的群体长时间进化而来。遗传分化指数统计检验显示，中国厦门海域的钩手水母种群与乐亭、东营、烟台和大连海域的钩手水母群体间存在较大的遗传分化，基因流受限（Fst > 0.25；P < 0.05；Nm < 1），基因交流匮乏和距离隔离可能是产生上述分化的主要因素。大连海域的钩手水母种群与烟台、东营海域的钩手水母群体间存在中等程度的遗传分化（0.05 < Fst < 0.15；P < 0.05；Nm > 4），本区域内的海流分布和复杂的生活史是导致遗传分化的重要因素。系统分析结果显示，钩手水母群体间单倍型存在2个明显的谱系分支，虽然有个别的单倍型在进化枝上稍有交叉，但来自同一群组的大部分个体多聚为一支，钩手水母群体具有明显的系统地理结构。本研究基于COI基因片段的黄渤海4个钩手水母群体与GenBank上下载的厦门种群共计5个地理群体共检测到15个变异位点，其单倍型多样性和核苷酸多样性为0.433 ± 0.056和（0.209 ± 0.035）%，而基于16S rRNA基因片段的5个钩手水母群体共检测到7个变异位点，其单倍型多样性和核苷酸多样性为0.345 ± 0.054和（0.134 ± 0.029）%。结果显示COI序列变异水平略高于16S rRNA，相比COI，16S rRNA基因片段更为保守。基于线粒体COI和16S rRNA基因片段的中国5个钩手水母群体均具有较低的单倍型多样性（Hd < 0.5）和较低的核苷酸多样性（π < 0.5%），预示着中国近海5个钩手水母群体近期发生过瓶颈效应或由少数种群产生的建立者效应。钩手水母地理群体间具有复杂的遗传模式，复杂的生活史、海流分布和距离隔离可能是影响钩手水母遗传结构的重要因素。
其他摘要Since the mid-to-late 1990s, jellyfish blooms have occurred frequently in the East China Sea, Yellow Sea and Bohai Sea. Jellyfish blooms can damage the structure and function of ecosystems, threatening local marine fisheries, coastal tourism and personal security, which arouses the extensive concern of scientists and government. Jellyfish has simple morphological characteristics, so it is difficult to determine whether the jellyfish populations collected in different waters are part of the same population or subpopulation. In order to clarify the classification and genetic characteristics of the populations, it is crucial to carry out phylogeographic research on jellyfish collected from different coastal waters. The population genetic characteristics of Aurelia coerulea based on 16S rRNA gene fragments were analyzed, and genetic analysis of Gonionemus vertens based on mitochondrial COI and 16S rRNA gene fragments were also carried out in Chinese coastal waters. The main results were as follows:1. The results of genetic population analysis of A. coerulea based on mitochondrial 16S rRNA gene fragments were as follows:The moon jellyfish A. coerulea is widely distributed in coastal Chinese waters and is one of the species of jellyfish which cause blooms in the Yellow Sea and Bohai Sea. Blooms of A. coerulea have been reported in both coastal marine waters and coastal aquaculture ponds. Four A. coerulea medusae populations collected from coastal waters and four A. coerulea ephyrae populations collected from aquaculture ponds were analyzed based on 16S rRNA gene fragments. 166 individuals of eight geographical populations were sequenced in the study. A blast search of the BLASTn database concluded that both the ephyrae collected in the aquaculture ponds were A. coerulea (Aurelia sp.1), and were the same subspecies as the moon jellyfish in coastal waters. The overall haplotype diversity and nucleotide diversity of A. coerulea were respectively 0.686 ± 0.032 (Hd > 0.5) and (0.329 ± 0.019)% (π < 0.5%). The Tajima's D tests and Fu’s Fs tests for all populations suggested that A. coerulea populations had experienced historical population expansion events. Pairwise fixation index (Fst) values showed that genetic difference existed between A. coerulea medusae collected in Weifang waters and the medusae collected in Qingdao waters, or between the medusae collected in Weifang waters and the ephyrae populations collected in Dongying, Laoting and Qingdao waters. There was limited gene flow among populations (Fst > 0.25, P < 0.05, Nm < 1). The genetic differentiation was not significant between A. coerulea medusae and ephyrae populations collected in Qingdao and Rongcheng waters, or between A. coerulea medusae collected in Caofeidian and ephyrae collected in Laoting. Because of the exchange of water between the coastal waters and aquaculture ponds, as well as the lack of geographical isolation, the A. coerulea collected in these two habitats belonged to the same genetic population. Phylogeographic analysis of the 16S rRNA region revealed that there was no significant correlation between the evolutionary relationship of the haplotypes and the distribution of geographic populations. There was no obvious systematic geographical structure among the populations in this study. This information will be helpful in analyzing the migration and dispersal of A. coerulea and determining whether different jellyfish blooms are the same species based on the results of genetic analysis.2. The results of genetic analysis of G. vertens populations based on mitochondrial COI and 16S rRNA gene fragments were as follows:G. vertens is widely distributed throughout the Atlantic and Pacific Oceans and is one of few venomous jellyfish species in China. To investigate the population genetic structure of G. vertens, we sequenced the mtDNA COI gene in 104 individuals collected from four geographic locations along the coast of the Yellow Sea and Bohai Sea, and the homologous sequences of another 182 individuals which were obtained from GenBank were also analyzed. The overall haplotype diversity and nucleotide diversity of G. vertens were respectively 0.743 ± 0.012 and (1.046 ± 0.097)%, the genetic diversity of G. vertens were comparatively high. This indicates that overall populations of G. vertens have evolved over a long period of time from a stable group. Pairwise fixation index (Fst) values showed that the largest population differentiation existed between the G. vertens population collected in Xiamen waters and the other four populations collected in Chinese coastal waters. There was limited gene flow among populations (Fst > 0.25, P < 0.05, Nm < 1). The factors leading to differentiation could include isolation of distance and the lack of gene flow among populations. A moderate level of population differentiation existed between G. vertens population collected from Dalian waters and populations collected from Dongying and Yantai waters (0.05 < Fst < 0.15, P < 0.05, Nm > 4). The complex life cycle characteristics, together with the prevailing ocean currents in this region, were proposed and discussed as the main contributing factors to this. Phylogeographic analysis of the COI region revealed two lineages. Although there was a slight crossover in the evolutionary branches of some haplotypes, most of the haplotypes were located on the same branch, indicating that the G. vertens populations had obvious systematic geographical structure.The mtDNA COI and 16S rRNA gene fragment collected from four geographic locations along the coast of the Yellow Sea and Bohai Sea, combining with the homologous sequences of Xiamen population which were obtained from GenBank were analyzed. The haplotype diversity and nucleotide diversity of five populations were respectively 0.433 ± 0.056 and (0.209 ± 0.035)%, with a total of 15 polymorphic nucleotide sites detected among the populations based on COI. The haplotype diversity and nucleotide diversity of G. vertens populations collected in Chinese coastal waters were respectively 0.345 ± 0.054 and (0.134 ± 0.029)%, with a total of 7 polymorphic nucleotide sites detected among the populations based on 16S rRNA. The genetic differentiation of G. vertens based on 16S rRNA was slightly less than that based on COI in this study, probably because 16S rRNA is more conservative than COI. The haplotype diversity (Hd < 0.5) and nucleotide diversity (π < 0.5%) based COI and 16S rRNA were comparatively low, indicating that the genetic bottleneck and founder effect were caused by minority populations in the five G. vertens populations collected in Chinese coastal waters. The results indicates that the complex life cycle characteristics, isolation of distance, together with the prevailing ocean currents in this region, were proposed and discussed as the main factors that determined the genetic patterns of G. vertens.
页数86
语种中文
文献类型学位论文
条目标识符http://ir.yic.ac.cnhttp://ir.yic.ac.cn/handle/133337/25262
专题中科院烟台海岸带研究所知识产出_学位论文

推荐引用方式
GB/T 7714刘青青. 中国近海两种水母的遗传多样性和种群遗传结构研究[D]. 中国科学院烟台海岸带研究所. 中国科学院大学,2018.


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