中国水域江豚种群遗传变异的研究

GENETIC VARIATION OF THREE POPULATIONS OF FINLESS PORPOISE (NEOPHOCAENA PHOCAENOIDES) IN CHINESE WATERS

运用ＰＣＲ产物的银染测序技术，测定了中国水域江豚长江种群、黄海种群和南海种群共１２头个体的２个长度分别为３１７ｂｐ和２４５ｂｐ的ｍｔＤＮＡ控制区序列，并以此分析了江豚种群的遗传变异。结果表明：中国水域江豚各种群的控制区序列所定义的单倍型互不相同，无共有的单倍型。以２个ｍｔＤＮＡ控制区片段的核苷酸序列，以及把２个片段合并后产生的较大片段的序列，用ＭＥＧＡ软件中的ＵＰＧＭＡ法构建的系统树把江豚聚类为三个分支，分别代表３个地理种群。种群内的遗传分化程度远远低于种群间的遗传分化程度，提示江豚不同种群之间可能已经有了显著的遗传分化，种群间缺乏基因交流。各种群在距今５８～１０８万年以前有一个共同祖先。３个江豚种群之间显著的遗传分化提示它们之间不大可能发生海江或江海迁移，同时也提示在进行江豚资源管理和物种保护时需要把它们作为不同的种群单元分别对待。

Two segments of the mitochondrial control region (D loop), which was 317bp and 245bp respectively, of 12 individuals of finless porpoise (Neophocaena phocaenoides) from the Yangtze River, the Yellow Sea, and the South China Sea, were amplified and sequenced by silver staining sequencing technique for PCR product. By the analysis of genetic variation of the finless porpoise the following results were obtained: The haplotypes were different among three populations. No common haplotype was shared by them. The phylogenetic trees constructed by UPGMA method in MEGA package, using the 2 nucleotide sequences, as well as the longer sequence (562bp) by combining the former 2 sequences, clustered the haplotypes into three clades corresponding to 3 geographical populations. The levels of genetic differentiation within each population were much lower than those between populations, which indicated that the populations have diverged. Three finless porpoise populations in Chinese waters had a common ancestor before 058～108 Mya ago. Because of the obvious genetic differentiation among three populations, they should be regarded as different population units in the conservation and resource management.