Zoologisches Forschungsmuseum Alexander Koenig, Molecular Biology Unit, Bonn, Germany.
Mol Biol Evol. 2010 Nov;27(11):2451-64. doi: 10.1093/molbev/msq130. Epub 2010 Jun 9.
Arthropods were the first animals to conquer land and air. They encompass more than three quarters of all described living species. This extraordinary evolutionary success is based on an astoundingly wide array of highly adaptive body organizations. A lack of robustly resolved phylogenetic relationships, however, currently impedes the reliable reconstruction of the underlying evolutionary processes. Here, we show that phylogenomic data can substantially advance our understanding of arthropod evolution and resolve several conflicts among existing hypotheses. We assembled a data set of 233 taxa and 775 genes from which an optimally informative data set of 117 taxa and 129 genes was finally selected using new heuristics and compared with the unreduced data set. We included novel expressed sequence tag (EST) data for 11 species and all published phylogenomic data augmented by recently published EST data on taxonomically important arthropod taxa. This thorough sampling reduces the chance of obtaining spurious results due to stochastic effects of undersampling taxa and genes. Orthology prediction of genes, alignment masking tools, and selection of most informative genes due to a balanced taxa-gene ratio using new heuristics were established. Our optimized data set robustly resolves major arthropod relationships. We received strong support for a sister group relationship of onychophorans and euarthropods and strong support for a close association of tardigrades and cycloneuralia. Within pancrustaceans, our analyses yielded paraphyletic crustaceans and monophyletic hexapods and robustly resolved monophyletic endopterygote insects. However, our analyses also showed for few deep splits that were recently thought to be resolved, for example, the position of myriapods, a remarkable sensitivity to methods of analyses.
节肢动物是最早征服陆地和空气的动物。它们涵盖了超过四分之三的已描述的生物物种。这种非凡的进化成功是基于惊人多样的高度适应性的身体结构。然而，目前缺乏强有力的解决的系统发育关系，阻碍了对潜在进化过程的可靠重建。在这里，我们表明，基因组数据可以大大提高我们对节肢动物进化的理解，并解决现有假说之间的几个冲突。我们组装了一个由 233 个分类单元和 775 个基因组成的数据集，最后使用新的启发式方法从中选择了一个信息量最优的数据集，其中包括 117 个分类单元和 129 个基因，并与未减少的数据集进行了比较。我们包括了 11 个物种的新的表达序列标签（EST）数据，以及所有已发表的基因组数据，并通过最近发表的关于分类学上重要的节肢动物类群的 EST 数据进行了扩充。这种彻底的抽样减少了由于分类单元和基因的抽样随机效应而获得虚假结果的机会。我们建立了基因的同源预测、对齐掩蔽工具和由于使用新的启发式方法平衡分类单元和基因的比例而选择最具信息量的基因。我们优化的数据集稳健地解决了主要的节肢动物关系。我们得到了对有爪动物和真节肢动物的姐妹群关系的强烈支持，对缓步动物和环神经动物的密切关联也得到了强烈支持。在泛甲壳类动物中，我们的分析得出了假的甲壳类动物和单系的六足动物，以及单系的内翅昆虫的稳健结果。然而，我们的分析也显示了一些深度分裂，这些分裂最近被认为是已经解决了的，例如多足动物的位置，这表明对分析方法的敏感性很高。
