SSU rRNA-based phylogenetic position of the genera Amoeba and Chaos (Lobosea, Gymnamoebia):: The origin of gymnamoebae revisited
SSU rRNA-based phylogenetic position of the genera Amoeba and Chaos (Lobosea, Gymnamoebia):: The origin of gymnamoebae revisited
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DOI：
10.1093/oxfordjournals.molbev.a003777
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发表时间：
2001-12-01
影响因子：
10.7
通讯作者：
Pawlowski, J
中科院分区：
文献类型：
--
作者：
Bolivar, I;Fahrni, JF;Pawlowski, J
裸叶变形虫（裸叶变形虫）是所有水生和陆地生物群落中数量最多的原生生物之一。然而，由于缺乏翔实的形态特征，对gymnamoebae的起源和进化历史知之甚少。最初的分子研究揭示了变形虫谱系的多个起源和变形虫物种的非凡多样性。然而，分子数据只存在于属于这一群的众多分类群中的少数种。在这里，我们展示了四种典型的大型gymnamoeae的小亚单位（SSU） rDNA序列：变形变形虫、leningradensis变形虫、Chaos nobile变形虫和Chaos carolinense。序列分析表明，这4种与sacamoeba属、Leptomyxa属、Rhizamoeba属、Paraflabellula属、Hartmannella属、Echinamoeba属亲缘关系较近。所有这些都形成了一个相对较好的支系，对应于Gymnamoebia亚类，与基于形态学的分类学一致。其他gymnamoeae成小群聚集或分开分支。它们的关系根据分析类型和核苷酸取代模型而变化。在邻域连接分析中，所有的gymnamoeae聚在一起，校正了位点间的异质性和不变位点的比例。然而，SSU rRNA基因序列在统计学上不支持这一分支，进一步分析蛋白质序列数据将需要验证gymnamoebae的单系性。
Naked lobose amoebae (gymnamoebae) are among the most abundant group of protists present in all aquatic and terrestrial biotopes. Yet, because of lack of informative morphological characters, the origin and evolutionary history of gymnamoebae are poorly known. The first molecular studies revealed multiple origins for the amoeboid lineages and an extraordinary diversity of amoebae species. Molecular data, however, exist only for a few species of the numerous taxa belonging to this group. Here, we present the small-subunit (SSU) rDNA sequences of four species of typical large gymnamoebae: Amoeba proteus, Amoeba leningradensis, Chaos nobile, and Chaos carolinense. Sequence analysis suggests that the four species are closely related to the species of genera Saccamoeba, Leptomyxa, Rhizamoeba, Paraflabellula, Hartmannella, and Echinamoeba. All of them form a relatively well-supported clade, which corresponds to the subclass Gymnamoebia, in agreement with morphology-based taxonomy. The other gymnamoebae cluster in small groups or branch separately. Their relationships change depending on the type of analysis and the model of nucleotide substitution. All gymnamoebae branch together in Neighbor-Joining analysis with corrections for among-site rate heterogeneity and proportion of invariable sites. This clade, however, is not statistically supported by SSU rRNA gene sequences and further analysis of protein sequence data will be necessary to test the monophyly of gymnamoebae.