用线粒体DNA D-loop区序列探讨盘丽鱼属鱼类系统分类

Taxonomy of Symphysodon based on mitochondrial D-loop gene sequences

迄今盘丽鱼属鱼类主要根据形态学特征进行分类，该属仅有一个种还是两个不同的种存在着争议。为了研究几种盘丽鱼属鱼类的亲缘关系，从分子水平探讨它们的分类地位，对绿盘丽鱼（Symphysodon aequifasciata aequifasciata）、褐盘丽鱼（S．a．axelrodi）和盘丽鱼（S．discus）共12个个体的线粒体DNA控制区（mtDNA D-loop）部分序列进行了分析，用邻接法和非加权组平均法构建了分子系统树，得到相同的拓扑结构。结果表明：盘丽鱼种内个体间的遗传距离为0．004～0．015；绿盘丽鱼与盘丽鱼间的遗传距离为0．042～0．050，褐盘丽鱼与盘丽鱼间的遗传距离为0.034～0．038，绿盘丽鱼与褐盘丽鱼间的遗传距离为0．050。盘丽鱼和绿盘丽鱼、褐盘丽鱼种间差异与绿盘丽鱼和褐盘丽鱼亚种间差异接近，推测盘丽鱼可能还没有分化到种的水平。

The taxonomy of Symphysodon is mainly based on morphology, however, there has been some disagreement on whether one species or two about this genus. In order to study the phylogenetic relationship of Symphysodon and probe into its taxonomy status on molecular level, we sequenced and compared 276 base pairs of mitoehondrial D- loop gene sequences from S. aequifasciata aequifasciata, S. a. axelrodi and S. discus, phylogenetic trees were constructed with neighbor-joining method and unweighted pair group method and obtained the same topology. The results showed that： The genetic distance of the 276 bp D-loop gene sequence was 0.004 - 0.015 among individuals of S. discus; 0. 042- 0. 050 between S. a. aequifasciata and S. discus, 0. 034- 0. 038 between S. a. axelrodi and 8. discus, and 0.050 between S. a. aequifasciata and S. a. axelrodi. The difference between two species of S. discus and S. aequifasciata was close to that of two subspecies between S. a. aequifasciata and S. a. axelrodi, which indicated that S. discus perhaps had not evolved to the level of species.