基于 rDNA ITS 1序列探讨臂尾轮属轮虫的系统发生关系

本文通过对剪形臂尾轮虫、矩形臂尾轮虫、十指臂尾轮虫、红臂尾轮虫、角突臂尾轮虫、双棘臂尾轮虫、裂足臂尾轮虫和萼花臂尾轮虫等八种臂尾轮虫rDNAITS 1序列分析,并以西氏晶囊轮虫为外群,使用PAUP和贝叶斯软件分别构建臂尾轮属轮虫系统发生树( MP树、NJ树、ML树和贝叶斯树) ,以探讨臂尾轮属的系统发生关系,并解决其中的一些分类问题。结果表明:本研究所涉及的轮虫rDNAITS 1平均序列差异百分比较高,为29 %;海水和淡水臂尾轮虫被明显分为不同的进化枝;除双棘臂尾轮虫外,在淡水臂尾轮虫中具有三对前棘刺且营附着生活的种类与前棘刺少于三对且营浮游生活的种类聚在不同支系中,这与以形态特征为主所进行的系统发生研究结果基本一致;所有的系统树均支持将十指臂尾轮虫作为一个独立的支系分离出来,裂足臂尾轮虫应归入臂尾轮属。

Phylogenetic relationships of Brachionus rotifers based on rDNA ITS 1 gene sequences

The rDNA ITS 1 gene sequences of eight Brachionus species including B.forficula, B.leydigi, B.patulus, B.rubens, B.angularis, B.bidentata, B.diversicornis and B.calyciflorus were analyzed, and using Asplanchna sieboldi as an outgroup, neighbor-joining (NJ), maximum-parsimony (MP), maximum-likelihood (ML) and Bayesian methods were used to reveal their phylogenetic relationships and resolve some taxonomic questions. The average percentage of divergence for rDNA ITS 1 gene sequences in 31 samples was 29%. The marine and the freshwater Brachionus species were clearly divided into different clades. Among the freshwater Brachionus rotifers, with the exception of B.bidentata, species having three pairs of anterior spines and being littoral, and those having less than three pairs of anterior spines and being planktonic were grouped in different clades. This was consistent with their morphological taxonomic status. All the phylogenetic trees showed that B.patulus was separated into an independent clade, and B.diversicornis belonged to the genus Brachionus.