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题名: 竿虾虎鱼谱系遗传分化与群体历史动态的初步研究
作者: 邓颖达
学位类别: 硕士
答辩日期: 2016-05-19
授予单位: 中国科学院大学
授予地点: 北京
导师: 刘进贤
学位专业: 海洋生态学
中文摘要:
当人们看到一类陌生的物种时,往往先从形态上进行测量。但由于地理隔离造成的基因交流限制和环境变化带来的选择压力,在近缘物种或种内谱系间,分子水平的显著分化可能先于其形态学差异而发生,这些从形态学无法或难以区分的隐存单元可能预示着新物种的形成。DNA分子序列标记提供的分子信息是物种进化历史和遗传边界的重要标度,尤其对于那些形态近似的隐存单元, DNA序列标记在其遗传多样性的研究方面更起到不可替代的作用。
竿虾虎鱼(Luciogobius guttatus)隶属于拟虾虎鱼亚科(Gobionellinae),已知分布于中国沿海、朝鲜半岛和日本的岩基砾石质潮间带。日本学者发现竿虾虎鱼在日本沿海存在三个谱系,但在我国,针对竿虾虎鱼的研究仅限于形态测量和野外调查记录。本研究基于线粒体DNA(RNA基因16S,蛋白基因COI、CYTB,控制区MCR)和核基因(内含子in177,内含子in417,外显子RYR3)序列标记,从系统发育和群体遗传两个角度,考察竿虾虎鱼在我国北方沿海的隐存多样性与群体历史。
研究结果显示,与日本分布的竿虾虎鱼对比,我国北方沿海分布的竿虾虎鱼存在以崂山为潜在屏障的偏南、偏北两个谱系,分别对应于日本沿海的谱系A和谱系C;缺少谱系B。谱系A和谱系C在中日沿海都存在同域分布的情形,而谱系B已知分布于西南日本沿海。根据已发表的分子数据,作者推测竿虾虎鱼可能起源于日本海的东南岸,随日本海的形成而多次向不同方向扩散。由于缺少化石标定,作者使用了松散的分子钟推断竿虾虎鱼的进化历史,结果表明谱系A形成时间最早,可追溯至晚中新世(约5至7百万年前);谱系B比谱系C更接近谱系A,并在线粒体基因上与地理上相距甚远的谱系C聚成内群。另一方面,虽然从线粒体DNA上分出的谱系能够与核基因上分出的谱系相对应,但分支模式有所不同:在所有使用CYTB建立的最大似然进化树上,谱系A与其他物种最先聚合;其他情况下,竿虾虎鱼各谱系可以聚成一个内群。进一步分析发现竿虾虎鱼不同基因中潜在功能模序的组成存在谱系间的差异,且谱系C的RYR3基因中存在罕见而偏离中性的非同义突变。另外,与预期相反,本研究中的内含子标记十分保守,in177不能区分竿虾虎鱼谱系。基于贝叶斯溯祖过程的种群历史反演,作者推测末次冰期对竿虾虎鱼的有效种群扩张和群体的分化及扩散起到关键作用,且不同谱系对冰期气候变化的反应并不一致:谱系C在中日之间的群体分化比谱系A更清晰且更早(始于末次盛冰期之前),并曾经历更强的瓶颈效应。
本研究初步查明了中国北方沿海竿虾虎鱼的遗传多样性现状,理清了竿虾虎鱼谱系分化的历史过程,增加了人们对海洋鱼类隐存多样性的认知,为我国竿虾虎鱼的保护提供了分子依据。
 
 关键词:     线粒体DNA,核基因,隐存多样性,竿虾虎鱼,群体分化

英文摘要: When people see a strange species, it is often the first to measure its appearance. But due to geographical isolation and selection pressure between closely related species or lineages, significant differentiation at the molecular level may occur prior to the morphological differences, and these morphologically hidden unit may indicates the formation of new species. DNA sequences provide irreplaceable information which helps uncovering the evolutionary history and genetic boundary of such approximated units.
In this study, DNA sequences were used to clarify the systematics of the flat-head goby (Luciogobius guttatus, Gobionellinae), an intertidal dweller in the stony coasts of East Asia. Former researches have shown that there are three lineages (A, B, C) of Luciogobius guttatus in the Japan Archipelago. However, previous studies in China focusing on L. guttatus are mainly limited to morphological measuring and survey records.
Based on both mtDNA (16S rRNA, COI, CYTB, mitochondrial control region) and nucDNA (two introns: in417 and in177, and one exon of RYR3), this study reports the cryptic diversity of their counterparts in northern China from the aspect of molecular systematics and population genetics, which has found that the latitudinal distribution of lineage A (southern) and C (northern) of is affected by Mountain Laoshan. Lineage A and C can be sympatric in both China and Japan, while lineage B has only been identified on the southwestern coasts in Japan. Known from published molecular data, the origin area of L. guttatus is deducted to be the southeastern coasts of the Sea of Japan, where the lineages begun to spread with the opening of the Sea of Japan in the inter-glacial period. Due to the lack of fossil calibration, the evolutionary history is reconstructed with a relaxed molecular clock. Results suggest lineage A is much older than previously thought, as roots back to the late Miocene; lineage B (compared to lineage C) is more similar to the ancestral lineage A, but these two inner taxa (lineage B and C on mitochondrial gene trees) are far separated geologically. On the other hand, although the lineages identified by mtDNA match those identified by nucDNA, the topology of the clades can be different: lineage A always clades with other species first when CYTB is used for a ML tree, and in other cases all three lineages of L. guttatus can be monophyletic. Further analysis indicates adaptational differentiation between lineage A and C on different genes. Moreover, a rare non-neutral non-synonymous mutation and more binding motifs were identified in lineage C, in comparison with lineage A. Being opposite to expectation, introns are conserved and in177 is not informative to identify a lineage in this study. Furthermore, the last glacial maximum (LGM) is a key event promoting the expansion, recovery and divergence of the populations of L. guttatus. Nonetheless, the reactions to the LGM are different in different lineages: in terms of divergence between population in China and Japan, lineage C is leading lineage A with a clearer phylogenetic pattern, and has experienced stronger bottleneck before the LGM.
Summed up, these results render the molecular basis for the conservation of L. guttatus on the coasts of northern China.
Key words     mtDNA, nucDNA, cryptic diversity, Luciogobius guttatus, population divergence
语种: 中文
内容类型: 学位论文
URI标识: http://ir.qdio.ac.cn/handle/337002/116987
Appears in Collections:海洋生态与环境科学重点实验室_学位论文

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Recommended Citation:
邓颖达. 竿虾虎鱼谱系遗传分化与群体历史动态的初步研究[D]. 北京. 中国科学院大学. 2016.
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