旋唇纲纤毛虫系统发育分子树构建的影响因素  

Impacts on the phylogenetic tree construction of ciliated protozoa inferred from the SS rRNA gene sequences of 36 spirotrichs

作　　者：伊珍珍[1] 陈子桂[1] 高珊[1] 宋微波[1] 

机构地区：[1]中国海洋大学教育部海水养殖重点实验室,山东青岛266003

出　　处：《动物学报》2007年第6期1031-1040,共10页ACTA ZOOLOGICA SINICA

基　　金：国家自然科学基金课题资助(No.30670280;No.40676076)~~

摘　　要：以36种旋唇类高等类群纤毛虫的核糖体小亚基核苷酸(Small subunit ribosomal RNA,SS rRNA)基因序列为素材,比较研究了不同条件(包括外类群、内类群的选择,同一基因不同序列长度的组合,不同建树方法和不同分析软件的使用)对纤毛虫分子系统树构建结果的影响。结果表明,上述因素均可不同程度地影响拓扑结构。结果同时提示,在利用有限数据进行相关研究,特别是在对未明类群的系统关系分析中,必须充分考虑因建树条件的不同所带来的影响。作者同时也建议,在当前可用的分子信息欠充分的前提下,对于纤毛虫任何类群的分子系统学探讨而言,慎重形成结论并尽可能地结合和参照形态学、发生学等资讯,仍是需优先考虑的工作路线。Molecular genetic studies alone are of limited value when assessing the evolutionary relationships of ciliated protozoa species, given that limited numbers and lengths of genes are available for analysis. Different algorithms and gene sequence matrixes typically yield different topologies, Using SS rRNA gene sequences of 36 spirotrichous ciliates belonging to three genera, Holosticha, Euplotes and Oxytricha, phylogenetic trees were constructed and compared in order to determine the effects of changing the tree topologies. In this work, different combinations of data sets were used, including different out-groups （i. e., Aspidisca steini , Pseudokeronopsis flava , Kiitricha marina, Loxodes striatus ）, different combinations of internal groups, different lengths of gene sequences, and different tree-construction algorithms （i. e., UPGMA, NJ and MP methods）. Results indicate that these eata sets could be used to construct different tree topologies. All of these should be seriously considered when assessing the molecular phylogenetic positions of some unknown/ambiguous ciliates based on gene sequences. Due to limited molecular information, morphological and morphogenetical characters of ciliated protozoa should also be taken into account prior to constructing phylogenetic trees and discussing the evolutionary relationships of any organisms inferred from limited genes and sequences [Acta Zoologica Sinica 53 （6）： 1031 - 1040, 2007].

关 键 词：纤毛虫 分子进化 系统树 SS RRNA基因 外类群 

分 类 号：Q951[生物学—动物学]