Limitations of metazoan 18S rRNA sequence data: Implications for reconstructing a phylogeny of the animal kingdom and inferring the reality of the Cambrian explosion
Limitations of metazoan 18S rRNA sequence data: Implications for reconstructing a phylogeny of the animal kingdom and inferring the reality of the Cambrian explosion
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DOI：
10.1007/pl00006397
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发表时间：
1998-10-01
影响因子：
3.9
通讯作者：
Meyer, A
中科院分区：
文献类型：
--
作者：
Abouheif, E;Zardoya, R;Meyer, A
我们记录了28个后生动物门的67个分类群的18 S rRNA分子的系统发育行为，并评估了位点率变化对重建动物王国的系统发育的影响。进行这种经验评估，以进一步澄清18 S rRNA基因作为系统发育标记的分辨率的限制，并解决18 S rRNA基因是否可以作为证据来源，以推断寒武纪大爆发的现实的问题。18 S rRNA分子的不同区域之间以及所有二级结构类别内存在显著程度的突变位点率变化。有一个显着的负相关性推断的核苷酸取代和系统发育信息之间的数量，以及与分子内的取代饱和度。在分类群内部和分类群之间都存在着基本成分的差异，在某些谱系中，差异较大;重要的是，排除具有不同de的位点，核苷酸取代程度显著影响最大简约性同源性以及相邻连接同源性的拓扑结构和分辨率（校正和未校正的位点速率变化），总之，这些数据表明18 S rRNA分子不适合用于重建所有后生动物门的进化历史，而多形分割，即，18 S rRNA基因组中未解决的节点，不能用作支持寒武纪大爆发假说的单一或可靠证据来源。
We document the phylogenetic behavior of the 18S rRNA molecule in 67 taxa from 28 metazoan phyla and assess the effects of among-site rate variation on reconstructing phylogenies of the animal kingdom. This empirical assessment was undertaken to clarify further the limits of resolution of the 18S rRNA gene as a phylogenetic marker and to address the question of whether 18S rRNA phylogenies can be used as a source of evidence to infer the reality of a Cambrian explosion. A notable degree of among-site rate variation exists between different regions of the 18S rRNA molecule, as well as within all classes of secondary structure. There is a significant negative correlation between inferred number of nucleotide substitutions and phylogenetic information, as well as with the degree of substitutional saturation within the molecule. Base compositional differences both within and between taxa exist and, in certain lineages, mag; be associated with long branches and phylogenetic position, Importantly, excluding sites with different de,degrees of nucleotide substitution significantly influences the topology and degree of resolution of maximum-parsimony phylogenies as well as neighbor-joining phylogenies (corrected and uncorrected for among-site rate variation) reconstructed at the metazoan scale, Together, these data indicate that the 18S rRNA molecule is an unsuitable candidate for reconstructing the evolutionary history of all metazoan phyla, and that the polytomies, i.e., unresolved nodes within 18S rRNA phylogenies, cannot be used as a single or reliable source of evidence to support the hypothesis of a Cambrian explosion.