武汉东湖圆形盘肠溞种群遗传结构分析

GENETIC STRUCTURES OF CHYDORUS SPHAERICUS POPULATIONS FROM LAKE DONGHU, WUHAN

为了评估人工堤坝分隔对武汉东湖浮游动物种群遗传结构的影响,以细胞色素氧化酶亚基Ⅰ(mitochondrial cytochrome coxidase subunitⅠ,COⅠ)基因为分子标记,通过PCR扩增和DNA测序技术并结合GenBank数据库中已有的相关序列,对武汉东湖圆形盘肠溞(Chydorus sphaericus)种群遗传多样性进行了分析。结果显示:7个样点采集的圆形盘肠溞并没有分为不同的类群,全局检验和种群间两两差异检验均显示7个圆形盘肠溞类群没有显著的遗传差异。构建的邻接树显示武汉东湖的圆形盘肠溞COⅠ基因聚为一枝,除加拿大育空地区Kookatsoon湖与武汉东湖的部分圆形盘肠溞COⅠ基因聚为一枝外,其他地区的圆形盘肠溞COⅠ基因都分别聚为不同的枝。对圆形盘肠溞COⅠ基因序列两两距离与样点间的地理距离进行相关分析显示,不论是东湖内的小空间尺度还是更大尺度上的圆形盘肠溞COⅠ基因都存在序列相似性随地理距离增加而降低("距离-衰减"模式),说明圆形盘肠溞存在分布限制。研究结果表明武汉东湖50年前修建的人工堤坝并未对武汉东湖圆形盘肠溞的种群遗传结构造成显著影响。

To estimate the possible influence of the artificial embankments on the genetic structure of Chydorus sphaericus in Lake Donghu, the CO I gene of C. sphaericus from Lake Donghu, Wuhan, was analyzed with classical DNA sequencing. The results showed that C. sphaericus collected from seven sampling sites at Lake Donghu were not classified into different groups. Both global test and pairwise difference test indicated that there was no remarkable in- heritance difference among seven C. sphaericus populations. The N-J tree indicated that CO I gene of C. sphaericus from Lake Donghu was clustered into one group and those from different regions were clustered into different groups except Lake Kookatsoon, Yukon Territory, which were clustered into the Lake Donghu group. The correlation analysis between pairwise distances of CO I gene sequences of C. sphaericus and geography distances among sampling sites showed that there were distance-decay relationships regardless within Lake Donghu or in larger scales. This result indi- cated that there was distribution restriction in C. sphaericus populations. In conclusion, the artificial embankments in Lake Donghu that were built 50 years ago did not cause remarkable influence on the genetic structure of C. sphaericus population in Lake Donghu. The relatively strong passive diffusivity of C. sphaericus in small scales may be one of the reasons that neutralized the influence of the artificial embankments on the population genetic structure.