Monophyly of Rhizaria and multigene phylogeny of unicellular bikonts
Monophyly of Rhizaria and multigene phylogeny of unicellular bikonts
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DOI：
10.1093/molbev/msl055
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发表时间：
2006-10-01
影响因子：
10.7
通讯作者：
Pawlowski, Jan
中科院分区：
文献类型：
--
作者：
Burki, Fabien;Pawlowski, Jan
重建真核生物的全球系统发育树是分子系统发育学面临的一项持续挑战。来自广泛真核生物门类的基因组数据有助于将真核生物树解析为具有较少数量大型类群的拓扑结构，但这些“超群”之间的关系仍有待确定。根足虫类（Rhizaria）是最近被确认的“超群”，然而，尽管在生命之树中具有重要地位，但在真核生物的全球系统发育研究中仍缺乏其代表物种。在此，我们报道了首次对真核生物系统发育进行的大规模分析，包括两种根足虫类物种的数据，即有孔虫类的丝状网足虫（Reticulomyxa filosa）和绿蜘藻（Bigelowiella natans）。我们的研究结果证实了根足虫类（有孔虫类 + 丝足虫类）的单系性，在所有分析中都具有很高的自举支持率。我们构建的系统发育树的整体拓扑结构与当前对真核生物系统发育的观点一致，即基部划分成“单鞭毛生物”（后鞭毛生物和变形虫类）和“双鞭毛生物”（植物界、囊泡虫类、不等鞭毛类和 excavates类群）。正如预期的那样，根足虫类在双鞭毛生物中分支；然而，它们的系统发育位置并不确定。根据数据集和分析类型的不同，根足虫类作为不等鞭毛类或excavates类群的姊妹群分支。总体而言，尽管使用了85种蛋白质以及迄今为止该部分系统发育树可用的最大分类学样本，但单细胞双鞭毛生物主要类群之间的关系仍未得到很好的解析。这可能是由于某些双鞭毛生物门类进化速率加快，或者与它们在真核生物早期进化过程中的快速分化有关。
Reconstructing a global phylogeny of eukaryotes is an ongoing challenge of molecular phylogenetics. The availability of genomic data from a broad range of eukaryotic phyla helped in resolving the eukaryotic tree into a topology with a rather small number of large assemblages, but the relationships between these "supergroups" are yet to be confirmed. Rhizaria is the most recently recognized "supergroup," but, in spite of this important position within the tree of life, their representatives are still missing in global phylogenies of eukaryotes. Here, we report the first large-scale analysis of eukaryote phylogeny including data for 2 rhizarian species, the foraminiferan Reticulomyxa filosa and the chlorarachniophyte Bigelowiella natans. Our results confirm the monophyly of Rhizaria (Foraminifera + Cercozoa), with very high bootstrap supports in all analyses. The overall topology of our trees is in agreement with the current view of eukaryote phylogeny with basal division into "unikonts" (Opisthokonts and Ameobozoa) and "bikonts" (Plantae, alveolates, stramenopiles, and excavates). As expected, Rhizaria branch among bikonts; however, their phylogenetic position is uncertain. Depending on the data set and the type of analysis, Rhizaria branch as sister group to either stramenopiles or excavates. Overall, the relationships between the major groups of unicellular bikonts are poorly resolved, despite the use of 85 proteins and the largest taxonomic sampling for this part of the tree available to date. This may be due to an acceleration of evolutionary rates in some bikont phyla or be related to their rapid diversification in the early evolution of eukaryotes.