武汉市湖泊微型裸腹溞种群遗传结构比较分析

分析武汉市9个湖泊中枝角类微型裸腹溞(Moina micrura)细胞色素氧化酶亚基Ⅰ(COⅠ)基因的多样性情况,对种群遗传多样性进行分析,了解不同地理距离对枝角类种群遗传分化的影响。形态鉴定表明,9个湖泊26个样点中共有8个湖泊17个样点检出微型裸腹溞,牛山湖设置的3个样点均未检测出微型裸腹溞。通过基因测序共得到66条微型裸腹溞COⅠ基因序列。由COⅠ基因序列构建的邻接树及Network分析显示,武汉8个湖泊中所得到的微型裸腹溞序列分为3大枝并具有14种不同的单倍体型。曼-惠特尼检验及科尔莫格罗夫-斯米尔诺夫检验均表明,湖泊内和湖泊间的微型裸腹溞遗传距离存在极显著差异。武汉市不同湖泊间微型裸腹溞存在遗传分化倾向。微型裸腹溞COⅠ基因在选择上是中性的,并且积累了相对较多的突变位点,可以用于种群遗传结构尤其是大尺度上的种群遗传结构分析。

Genetic Structure of Moina micrura Populations in Wuhan Lakes

The environment is changing continuously due to human activities and this is causing changes in the biota and community composition. The diversity of a single gene, mitochondrial cytochrome c-oxidase subunit 1 (COI) of Moina micrura (M. micrura), from nine lakes in Wuhan was analyzed to evaluate the impact of human activities on the genetic diversity of zooplankton in an urban lake. In July and August of 2012, M. micrura sampling was carried out at 26 sites on nine lakes within Wuhan City; Donghu Lake, Tangxun Lake, Yuehu Lake, Nanhu Lake, JinYin Lake, Wuhu Lake, YanXi Lake, Shahu Lake and Niushan Lake. M. micrura were observed at 17 of the sampling sites in eight lakes using morphological identification (M. micrura was not detected in Niushan Lake). A total of 66 different CO I gene sequences in M. micrura were obtained by gene sequencing and each was confirmed as M. micrura by comparison with the GenBank database. Phylogenetic trees of the 66 CO I gene sequences and ten CO I gene sequences for Chydorus sphaericus in Donghu Lake were constructed using the neighbor joining (N-J) method. Phylogenetic trees show that the CO I gene sequences of M. micrura from 8 lakes clustered into 3 clades, while the 10 CO I gene sequences of Chydorus sphaericus in Donghu Lake clustered into one clade. The unrooted parsimony network suggests that there are 14 haplotypes of M. micrura in the eight lakes. Both the Mann-Whitney Test (Z=-8.044, P<0.001) and Kolmogorov-Smirnov Test (Z = -8.044, P<0.001) indicate that there is a highly significant difference in the genetic distance of M. micrura populations within-lakes compared to those between-lakes, with an overall mean distance of 0.032 and a maximum genetic distance of 0.092. A box diagram of M. micrura genetic diversity also indicates a significant difference in the genetic distance of M. micrura within-lakes compared to between-lakes. In conclusion, obvious genetic differences exist among the M. micrura populations from different lakes in Wuhan City. Inland water bodies are normally isolated from one other and we postulate that M. micrura populations from different lakes gradually diverge due to lack of gene exchange and adaptation to different lake environments. The CO I gene of M. micrura can be used for analyzing population genetic structure, particularly the large scale structure.