Gong Ying-Chun, Yu Yu-He, Villalobo Eduardo, Zhu Fei-Yun, Miao Wei
Laboratory of Taxonomy and Ecology of Protozoa, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, China.
J Eukaryot Microbiol. 2006 Sep-Oct;53(5):397-403. doi: 10.1111/j.1550-7408.2006.00121.x.
Based on morphological characters, peritrich ciliates (Class Olygohymenophorea, Subclass Peritrichia) have been subdivided into the Orders Sessilida and Mobilida. Molecular phylogenetic studies on peritrichs have been restricted to members of the Order Sessilida. In order to shed more light into the evolutionary relationships within peritrichs, the complete small subunit rRNA (SSU rRNA) sequences of four mobilid species, Trichodina nobilis, Trichodina heterodentata, Trichodina reticulata, and Trichodinella myakkae were used to construct phylogenetic trees using maximum parsimony, neighbor joining, and Bayesian analyses. Whatever phylogenetic method used, the peritrichs did not constitute a monophyletic group: mobilid and sessilid species did not cluster together. Similarity in morphology but difference in molecular data led us to suggest that the oral structures of peritrichs are the result of evolutionary convergence. In addition, Trichodina reticulata, a Trichodina species with granules in the center of the adhesive disc, branched separately from its congeners, Trichodina nobilis and Trichodina heterodentata, trichodinids without such granules. This indicates that granules in the adhesive disc might be a phylogenetic character of high importance within the Family Trichodinidae.
基于形态特征，周丛纤毛虫（寡膜纲，周丛亚纲）已被细分为固着目和游动目。对周丛纤毛虫的分子系统发育研究一直局限于固着目的成员。为了更深入了解周丛纤毛虫内部的进化关系，利用四种游动目物种——高贵车轮虫、异齿车轮虫、网状车轮虫和迈阿卡小车轮虫的完整小亚基核糖体RNA（SSU rRNA）序列，采用最大简约法、邻接法和贝叶斯分析构建系统发育树。无论使用哪种系统发育方法，周丛纤毛虫都不构成一个单系类群：游动目和固着目物种没有聚类在一起。形态上的相似性但分子数据上的差异使我们认为，周丛纤毛虫的口器结构是进化趋同的结果。此外，网状车轮虫，一种在黏着盘中心有颗粒的车轮虫物种，与其同属的、没有这种颗粒的高贵车轮虫和异齿车轮虫分支不同。这表明黏着盘中的颗粒可能是车轮虫科内一个非常重要的系统发育特征。
