基于线粒体细胞色素b基因片段序列变异探讨3种鲳属鱼类系统进化

对鲳属3种鱼类共19个个体的细胞色素b（Cytb）基因进行PCR扩增,经比对校正得到1123bp的基因片段,共检测到141个变异位点,总变异为12.56%,5个简约信息位点,未出现插入和（或）缺失,序列中转换（Transition）明显多于颠换（Transversion）。鲳属3种鱼类19个序列共检测到11种单倍型,其T、C、A和G平均含量分别为29.1%、30.5%、27.4%和13.0%。（A＋T）%为56.5%,大于（G＋C）43.5%。结合来自GenBank中的鲳科的中间低鳍鲳Peprilus medius和星斑真鲳Stromateus stellatus的相应同源序列,并以长鲳科的刺鲳Psenopsis anomala作为外群,构建系统进化树。结果显示,翎鲳和中国鲳亲缘关系较近,二者与银鲳亲缘关系较远,同为鲳科的鱼类聚类后再与作为外群的刺鲳相聚。系统进化树显示,银鲳为3种鲳属鱼类中较早分化出的种,刺鲳位于进化树的基部,是较鲳属鱼类更为原始的类群,与形态分析结果一致。

Phylogenetic relationships of Pampus inferred from mitochondrial cytochrome b sequences

The classification and relationships of Pampus have been disputed for almost 200 years. The confusion and debates have brought much trouble to the study of phylogenetie relationships. Irately, some researchers partitioned Pampus into 5 species according to the mor phological specializations in China seas. In this study, to evaluate the phylogenetie relationship of 3 species （Pampus argenteus, P. punctatissimus, p. chinensis） from the China Seas, the mitochondrial cytochrome b gene of 19 individuals were amplified using PCR techniques. About 1150bp length fragments were obtained and sequenced. After being aligned, a fragment of 1123 bp nucleotide sequence which could be used for sequence analysis was obtained. The genetic in formation indexes, including Kimura-2 parameter genetic distance, basal composition and phylogenetic trees were generated using MEGA3.1 software. Of the 1 123 aligned base pairs, 141 sites were variable. The mutation sites were mainly transition and transversion. Transitions were found to be more common than transversions which suggested that the sequences had not reached saturation. The average basic compositions of all sequences were as follows： 29.1 % T, 30.5℃, 27.4%o A, and 13.0% G. Of the 19 sequences we defined 11 haplotypes. The genet- ic distances between haplotypes ranged from 0.1% to 11%. The sequences were combined with homologous sequences of Peprilus medius , Stromateus stellatus and Psenopsis anomala down- loaded from GenBank. Molecular phylogenetie trees were constructed by neighbor-joining （NJ） and minimum evolution （ME） methods based on the 1 123 bp Cytb gene sequences, with P. anomala as the designated outgroup. Both NJ tree and ME tree indicated a closer relationship between P. punctatissimus and P. chinensis and a farther relationship between P. argenteus and the above two species. P. anomala was basal in the NJ and ME tree and diverged before Stromateidae. The result is consistent with the conclusion of morphological analysis.