铜鱼线粒体控制区的序列变异和遗传多样性

MtDNA CONTROL REGION SEQUENCE VARIATION AND GENETIC DIVERSITY OF COREIUS HETERODON(BLEEKER) IN THE UPPER AND MIDDLE SECTIONS OF THE YANGTZE RIVER

采用PCR和DNA测序技术研究长江中上游野生铜鱼的遗传多样性和群体遗传学特征,从9个采样点共获得100尾铜鱼,用于分析的线粒体DNA控制区的片段序列为946bp。在100个序列中,共检测出变异位点47个(其中增添/缺失位点8个),单倍型41种。9个地理群体的平均单倍型多样性(Hd)和平均核苷酸多样性(Pi)分别为0.9257±0.0162和0.004178±0.002337,表现出较贫乏的遗传多样性。群体间的分化指数(FST值)、平均基因流(Nm)、分子方差分析(AMOVA)和平均K2-P遗传距离均表明9个铜鱼地理群体间存在广泛的基因交流,未明显发生群体遗传分化。另外,共享单倍型比例较高,约为34%(14/41)。单倍型的UPGMA分子系统树和简约网络图显示单倍型的聚类与地理分群没有相关性。上述结果表明9个铜鱼地理群体属于同一种群。

Brass gudgeon （Coreius heterodon） is an endemic species in China, and mainly distributes in the upper and middle sections of the Yangtze River. The fish population has been greatly decreased these years due to various factors, such as destruction of spawning condition, water pollution, over exploitation and so on. In order to protect the fish population, it is necessary to study genetic diversity of the fish population. The fish specimens were collected from 9 sampling locations in the upper and middle sections of the Yangtze River, i. e., Hechuan （HC）, Mudong （MD）, Fuling （FL）, Wanzhou （WZ）, Wushan （WS）, Sandouping （SDP）, Yichang （YC）, Yueyang （YY） and Jinkou （JK）. The specimen number was in Tab. 1. The mitochondrial D-loop region （control region） of the fish was amplified by polymerase chain reaction （PCR） technology and sequenced with ABI 3730 sequencer. 100 sequences were analyzed using some softwares, viz., Clustal X 1.83, MEGA 3.1, DnaSP 4.50.3 and Arlequin v3.01. The results were as follows： Every specimen sequence was 946 bp for genetic diversity analysis of the fish. Both 47 mutations of nucleotide acids including 8 inserting or deleting ones and 41 haplotypes were found in the 100 sequences. About 34% of the 41 haplotypes presented at least in two or more geographic groups and every one of 27 haplotypes just appeared in single one of the 9 groups. The UPGMA tree and the Parsimony network of 41 haplotypes showed that the clustering of haplotypes did not correspond to every geographic group of the fish. Genetic structure analysis showed a low level genetic diversity of C. heterodon （Hd=0.9257±0.0162, Pi=0.004178±0.002337）. The AMOVA analysis indicated that 99.66% of the total variation in D-loop region sequence came from nucleotide acid mutations of the fish individuals in the 9 geographic populations, and just 0.34% from variation between the 9 geographic populations, which showed little genetic differentiation between the 9 geographic groups. Meanwhile, average Kimura 2-parameter distances （Tab. 6）, the FST value （Tab. 4） and Nm value （20.84） also revealed little genetic differentiation between the 9 geographic groups. All the data mentioned above indicated that the 9 geographic groups belonged to single nature population.