Multigene analyses of bilaterian animals corroborate the monophyly of Ecdysozoa, Lophotrochozoa, and Protostomia
Multigene analyses of bilaterian animals corroborate the monophyly of Ecdysozoa, Lophotrochozoa, and Protostomia
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DOI：
10.1093/molbev/msi111
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发表时间：
2005-05-01
影响因子：
10.7
通讯作者：
Brinkmann, H
中科院分区：
文献类型：
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作者：
Philippe, H;Lartillot, N;Brinkmann, H
近十年前，从小亚基核糖体RNA(RRNA)中推断出一种新的双边动物系统发育，该核糖体RNA声称两大类原生动物为单系动物：蜕皮动物(如节肢动物、线虫、指甲虫和迟滞动物)和细毛虫动物(如环节动物、软体动物、扁形蠕虫、腕足动物和轮虫)。然而，它几乎没有得到额外的支持。事实上，一些多基因分析强烈反对这种新的系统发育。这些后一项研究是基于大量的序列数据，因此显示出明显强大的统计学支持。然而，他们只涵盖了几个分类群(那些可以获得完整基因组的分类群)，使得重建树木的系统人工制品变得更有可能。在这里，我们扩展了这种稀疏的分类抽样，并分析了来自不同动物样本(35个物种)的大型数据集(146个基因，35,371个位置)。我们的研究表明，在rRNA和多基因分析之间观察到的不一致确实是由于长分支吸引伪像，说明了系统偏差对系统遗传学研究的巨大影响。对我们的数据集的精细分析排除了最具偏见的基因，为新的动物系统发育提供了强有力的支持，此外，还表明尾索动物与脊椎动物的亲缘关系比头索动物更近。这些发现对解释形态和基因组数据具有重要意义。
Almost a decade ago, a new phylogeny of bilaterian animals was inferred from small-subunit ribosomal RNA (rRNA) that claimed the monophyly of two major groups of protostome animals: Ecdysozoa (e.g., arthropods, nematodes, onychophorans, and tardigrades) and Lophotrochozoa (e.g., annelids, molluscs, platyhelminths, brachiopods, and rotifers). However, it received little additional support. In fact, several multigene analyses strongly argued against this new phylogeny. These latter studies were based on a large amount of sequence data and therefore showed an apparently strong statistical support. Yet, they covered only a few taxa (those for which complete genomes were available), making systematic artifacts of tree reconstruction more probable. Here we expand this sparse taxonomic sampling and analyze a large data set (146 genes, 35,371 positions) from a diverse sample of animals (35 species). Our study demonstrates that the incongruences observed between rRNA and multigene analyses were indeed due to long-branch attraction artifacts, illustrating the enormous impact of systematic biases on phylogenomic studies. A refined analysis of our data set excluding the most biased genes provides strong support in favor of the new animal phylogeny and in addition suggests that urochordates are more closely related to vertebrates than are cephalochordates. These findings have important implications for the interpretation of morphological and genomic data.