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中国近海重要生态建群红藻真江蓠(Gracilaria vermiculophylla)的居群遗传多样性研究
刘若愚
Subtype硕士
Thesis Advisor段德麟 ; 胡自民
2016-05-25
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline海洋生物学
Keyword真江蓠 Cox1 Aflp 遗传多样性 遗传分化
Abstract真江蓠(Gracilaria vermiculophylla (Ohmi) Papenfuss)隶属红藻门(Rhodophyta),真红藻纲(Florideophyceae),江蓠目(Gracilariales),江蓠科(Gracilariaceae),江蓠属(Gracilaria),是中国近海潮间带生态系统结构组成和功能维持的重要支撑物种,但目前有关其居群遗传结构和多样性分布模式的研究仍较为缺乏。本研究利用线粒体cox1序列和AFLP标记对我国近海真江蓠地理居群进行居群遗传结构分析,获悉该物种在中国近海的多样性组成特征和遗传变异的时空分布模式,试图解释形成这种地理分布模式的潜在因素。主要结果如下:
1.      利用线粒体cox1序列对我国近海18个真江蓠地理居群(426个样本)进行系统发育和居群遗传分析。通过PCR扩增获得641 bp的cox1基因序列,它们在426株真江蓠样本中含有21个变异位点,产生15个单倍型。基于cox1序列的系统进化分析、单倍型分析和主成分分析显示真江蓠的18个居群已分化为南北两个类群,其中浙江嵊泗以北的13个居群形成北方类群,福建厦门以南的5个居群形成南方类群。北方类群(单倍型H5-H11)同南方类群(单倍型H0-H4)之间存在显著的遗传分化(FST = 0.916),彼此间基因交流较少(Nm = 0.020)。线粒体cox1序列的变异水平(3.72 %)和遗传距离(0.215)显示中国近海真江蓠南北类群间的遗传分化达到亚种水平。
2.      利用AFLP标记对我国近海17个真江蓠地理居群(421个样本)进行居群遗传结构和多样性分析。5对选择性扩增引物在421株个体中共扩增出987个条带,其中多态性位点比例为43.97%,其它各项遗传多样性参数都较小,表明中国近海真江蓠的居群遗传多样性偏低。遗传距离、系统进化、主成分和Structure结果一致将中国近海真江蓠居群分成南北两大类群,且彼此间遗传分化显著,基因交流参数Nm < 1。北方类群中含有三种基因型的真江蓠,分别为青岛基因型、山东半岛基因型和辽东半岛基因型。青岛一浴(YY)和青岛二浴(EY)居群仅含有青岛基因型的真江蓠,辽东半岛居群【大连黄泥川(HN)、大连黑石礁(HS)和大连獐子岛(ZZ)】仅含有辽东半岛基因型的真江蓠。而山东半岛居群【威海石岛(SD)、威海东楮岛(DC)、威海鸡鸣岛(JM)、烟台长岛(CD)】除了山东半岛基因型个体外,还混有辽东半岛基因型的真江蓠个体。三个北方基因型的真江蓠个体在小麦岛附近的青岛三浴(SY)、银海国际(YH)和石老人(LR)海域交汇混杂。除近岸流的推动作用外,我们推测上世纪60-90年代初期的真江蓠采孢子育苗实验和海区筏式养殖实验在青岛海域的真江蓠居群遗传类型呈现混杂这一事件中发挥重要作用。
本研究发现中国近海的真江蓠南北类群间的分化达亚种水平,真江蓠南方类群与真江蓠简枝变种/形(Gracilaria vermiculophylla var. zhengii)的遗传关系较近。真江蓠北方类群含有青岛基因型、山东半岛基因型和辽东半岛基因型等三种基因型的真江蓠,在地理位置上大致以山东青岛的小麦岛附近海域为界分化为两大地理亚群,二者呈现中度遗传分化(Fst = 0.142)。山东半岛和辽东半岛的真江蓠居群间基因交流频繁,主要表现为辽东半岛基因型向山东半岛扩张,但二者仍表现出较大的遗传分化(Fst = 0.225)。中国近海真江蓠南北分化的界限及形成现有地理分布格局的原因有待进一步丰富采样和整合亲缘地理学分析来解决。
Other AbstractThe red alga Gracilaria vermiculophylla taxonomically belongs to Gracilaria, Gracilariaceae, Gracilariales, Florideophyceae, Rhodophyta. As a habitat-forming species, it has been demonstrated to play an essential role in shaping coastal marine communities and maintaining intertidal ecosystems along the China coasts. Few studies however have been conducted about population genetic structure and distribution patterns of genetic variation. In this master thesis, we compiled partial mitochondrial DNA cytochrome c oxidase subunit I gene (cox1) and amplified fragment length polymorphism (AFLP) marker to perform DNA-based barcoding identification and population genetic surveys. The main results are summarized as follows:
First of all, 426 samples from 18 geographic populaions were collected and applied to amplify mitochondrial cox1 sequnences. We obtained 641 bp of mtDNA cox1 sequences which identified 21 polymorphic sites and yielded 15 haplotypes. Phylogenetic inferences, haplotype networking and principal coordinate analysis consistently indicated that G. vermiculophylla populations along the China coasts have diverged into two groups: the North group comprises specimens from the Yellow-Bohai Sea and the Shengsi Island, and the South group comprises specimens from the five locations south of Xiamen, Fujian province. Molecular variance and Nei’s genetic distances revealed low genetic differentiation between populations in each group while the group-level of genetic divergence is comparable to the degree of subspecies differentiation in the genus Gracilaria.
Furthermore, 421 individuals from 17 geographic populaions were surveyed for AFLP analysis. Totally, 987 bands with size ranging from 60 to 500 bp were detected across all samples using 5 selective primer combinations in capillary electrophoresis. Of these bands 434 are polymorphic and account for 43.97%. We calculated genetic diversity parameters and Nei’s genetic distance, constructed Neighbor-joining phylogenetic tree and conducted PCA and Strcuture analysis. These analyses revealed that G. vermiculophylla has diverged into South and North groups which are concordant with the results detected by cox1 marker. The South group may represent the variant Gracilaria vermiculophylla var. zhengii. Within the North group, AFLP also decteced genetic differentiation between sub-group North 1 which comprised YY,  EY, SY and YH individuals and sub-group North 2 which comprises specimens from LR, SD, DC, JM, CD, HN, HS and ZZ. Individuals in the two northern sub-groups exchanged, infiltrated and intergrated in the area around the Maidao Island, Qingdao city. We also detected great genetic differentiation (FST = 0.225) between Shandong peninsula and Liaodong peninsula which may be due to frequent genetic exchange (Nm = 1.486).
Subject Area海洋生物学 ; 海洋调查与监测 ; 分子遗传学 ; 进化遗传学 ; 生态遗传学 ; 群体遗传学 ; 分子生物学 ; 生物进化论 ; 种群生态学 ; 水产生物学
Language中文
Document Type学位论文
Identifierhttp://ir.qdio.ac.cn/handle/337002/116971
Collection实验海洋生物学重点实验室
Affiliation1.中国科学院海洋研究所
2.中国科学院大学
Recommended Citation
GB/T 7714
刘若愚. 中国近海重要生态建群红藻真江蓠(Gracilaria vermiculophylla)的居群遗传多样性研究[D]. 北京. 中国科学院大学,2016.
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