| 摘要: |
| 为了解太湖的湖鲚(Coilia nasus taihuensis)与短颌鲚(Coilia brachygnathus)的遗传多样性及遗传分化情况，利用线粒体细胞色素b(Cyt-b)基因，开展了种群遗传学研究。结果显示，47条序列共有变异位点26个，其中，简约信息位点12个，共得到22个单倍型。两物种间Fst值达0.703，分化程度较高，种群间的基因流仅为0.212。湖鲚种群内平均Kimura双参数遗传距离为0.002，短颌鲚种群内为0.001，而湖鲚与短颌鲚种间平均Kimura双参数遗传距离为0.005，湖鲚与短颌鲚种间遗传距离高于湖鲚种群内部遗传距离，也高于短颌鲚种群内部遗传距离。系统发育树和单倍型网络图结果显示，湖鲚与短颌鲚分成2个大的类群，但有1个湖鲚个体与短颌鲚具有共有单倍型。总体结果显示，湖鲚与短颌鲚之间存在明显的遗传分化，Cyt-b序列可用于区分湖鲚与短颌鲚个体。 |
| 关键词: 湖鲚 短颌鲚 Cyt-b 遗传分化 |
| DOI： |
| 分类号: |
| 基金项目: |
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| Genetic Divergence of Coilia nasus taihuensis and Coilia brachygnathus Populations Based on the Mitochondrial Cyt-b Gene |
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XUAN Zhongya1, JIANG Tao2, LIU Hongbo2, CHEN Xiubao2, YANG Jian1,2
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1.Wuxi Fisheries College, Nanjing Agricultural University, Wuxi 214081;2.Key Laboratory of Fishery Eco-Environment Assessment and Resource Conservation in Middle and Lower Reaches of the Yangtze River, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi 214081
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| Abstract: |
| Coilia nasus taihuensis has become a dominant species of fish in Taihu Lake, China. However, C. nasus taihuensis is often confused with C. brachygnathus, and identification problems still exist today. The fish with length ratio of supermaxilla/head > 1 are believed to be the former species, while those with length ratio of supermaxilla/head < 1 are believed to be the latter. As previous studies have classified all of the Coilia fish in Taihu Lake as C. nasus taihuensis, there are doubts about the accuracy of the results of these studies on genetic differentiation between C. nasus taihuensis and C. brachygnathus. In light of the above information, we have used morphological features to distinguish between C. nasus taihuensis and C. brachygnathus, determined genetic divergences among the two putative species, and tested whether the Cyt-b sequence can identify unknown individuals at early life stages between C. brachygnathus and C. nasus taihuensis. In the present study, we have determined the genetic diversity, genetic structure, genetic divergence, and population demographic history between the two phenotypes of C. nasus taihuensis and C. brachygnathus, using the mitochondrial Cyt-b gene. A total of 22 haplotypes were found among 47 sequences of the Cyt-b gene, from the 33 individuals of C. nasus taihuensis and 14 individuals of C. brachygnathus. The results showed that 26 polymorphic nucleotide sites were detected among all of the Cyt-b sequences, including 12 parsimony-informative sites. The value of Kimura’s two-parameter distance for C. nasus taihuensis and C. brachygnathus was 0.002 and 0.001, respectively. Moreover, the value of Kimura’s two-parameter distance among C. nasus taihuensis and C. brachygnathus, was 0.005. This situation means that the genetic divergence among the two putative species was higher than that within each species. Fst analysis showed a significantly higher level of genetic variance among the two putative species (Fst=0.703, P≤0.001). The gene flow between the two putative species was 0.212, lower than 1, and suggesting that the two phenotypes had almost no gene exchange. Additionally, two distinct clades were detected by phylogenetic analysis, and they were for C. nasus taihuensis and C. brachygnathus, respectively. A haplotype was shared by these phenotypes. Furthermore, the median-joining network produced was similar to the topology of the phylogenetic tree. In summary, mtDNA analysis of this study revealed that there were significant genetic divergences between C. nasus taihuensis and C. brachygnathus, the gene flow between them was weak, and two distinct clades could be detected by phylogenetic analysis, and the Cyt-b sequence could be used to differentiate at early life stages between C. brachygnathus and C. nasus taihuensis. |
| Key words: Coilia nasus taihuensis Coilia brachygnathus Cyt-b Genetic divergence |
