Phylogenetic analysis of mitochondrial protein coding genes confirms the reciprocal paraphyly of Hexapoda and Crustacea.
Phylogenetic analysis of mitochondrial protein coding genes confirms the reciprocal paraphyly of Hexapoda and Crustacea.
复制标题
线粒体蛋白质编码基因的系统发育分析证实了己糖和甲壳类的互惠。
DOI：
10.1186/1471-2148-7-s2-s8
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发表时间：
2007-08-16
影响因子：
3.4
通讯作者：
Frati, Francesco
中科院分区：
文献类型：
--
作者：
Carapelli, Antonio;Lio, Pietro;Nardi, Francesco;van der Wath, Elizabeth;Frati, Francesco
节肢动物的系统发育至今仍是系统学家们争论的焦点，形态学和分子生物学研究之间存在着重大分歧。特别是，虽然连接六足动物和甲壳动物的分类单元（Pancrustacea）现在被动物学家广泛接受，但其基础谱系之间的关系，特别是甲壳动物和六足动物的相互平行系统，仍然是一个挑战。在分子系统发育研究中，已经使用了几个基因以及不同的分子标记来解决这个问题，其中线粒体DNA是选择的分子之一。在这项研究中，我们收集了迄今为止最大的Pancrustacea数据集，由100个完整（或几乎完整）的线粒体基因组序列组成。在去除不可重复的序列区域和高度重排的基因组后，我们使用13个蛋白质编码基因的核苷酸和推断的氨基酸序列来重建泛甲壳纲主要谱系之间的系统发育关系。用贝叶斯推断进行分析，并且对于氨基酸序列，开发了一种新的Pancrustacea特异性氨基酸置换矩阵并用于本研究。从核苷酸和氨基酸数据集的分析中获得了两个大部分一致的树。特别是，基于新的氨基酸置换矩阵（MtPan）获得的最佳树优于使用先前可用的矩阵（MtArt和MtRev）获得的最佳树，因为其可能性得分较高。最显著的结果是六足动物和甲壳动物的相互并系，甲壳动物的某些谱系（即软甲纲、鲸类和可能的鳃足动物）与昆虫纲的关系更密切。（外颚类）比两个目的基础六足动物，弹尾目和双尾目。我们的研究结果证实，线粒体基因组，不像基于形态学数据或核基因的分析，一贯支持非单系的六足动物。六足动物和甲壳动物的相互并系的发现表明了一种进化情景，在这种情景中，六足动物条件的获得可能在从不同的甲壳类祖先下降的谱系中独立地发生了几次，这可能是陆地化过程的结果。如果这一假设得到证实，我们应该重新思考我们对节肢动物进化的解释，其中陆生化可能导致通过趋同获得相似的解剖特征。与此同时，尽管使用了更大的数据集和更强大的分析方法，但基于形态学、核和线粒体数据集的重建之间的分歧似乎仍然存在。
The phylogeny of Arthropoda is still a matter of harsh debate among systematists, and significant disagreement exists between morphological and molecular studies. In particular, while the taxon joining hexapods and crustaceans (the Pancrustacea) is now widely accepted among zoologists, the relationships among its basal lineages, and particularly the supposed reciprocal paraphyly of Crustacea and Hexapoda, continues to represent a challenge. Several genes, as well as different molecular markers, have been used to tackle this problem in molecular phylogenetic studies, with the mitochondrial DNA being one of the molecules of choice. In this study, we have assembled the largest data set available so far for Pancrustacea, consisting of 100 complete (or almost complete) sequences of mitochondrial genomes. After removal of unalignable sequence regions and highly rearranged genomes, we used nucleotide and inferred amino acid sequences of the 13 protein coding genes to reconstruct the phylogenetic relationships among major lineages of Pancrustacea. The analysis was performed with Bayesian inference, and for the amino acid sequences a new, Pancrustacea-specific, matrix of amino acid replacement was developed and used in this study. Two largely congruent trees were obtained from the analysis of nucleotide and amino acid datasets. In particular, the best tree obtained based on the new matrix of amino acid replacement (MtPan) was preferred over those obtained using previously available matrices (MtArt and MtRev) because of its higher likelihood score. The most remarkable result is the reciprocal paraphyly of Hexapoda and Crustacea, with some lineages of crustaceans (namely the Malacostraca, Cephalocarida and, possibly, the Branchiopoda) being more closely related to the Insecta s.s. (Ectognatha) than two orders of basal hexapods, Collembola and Diplura. Our results confirm that the mitochondrial genome, unlike analyses based on morphological data or nuclear genes, consistently supports the non monophyly of Hexapoda. The finding of the reciprocal paraphyly of Hexapoda and Crustacea suggests an evolutionary scenario in which the acquisition of the hexapod condition may have occurred several times independently in lineages descending from different crustacean-like ancestors, possibly as a consequence of the process of terrestrialization. If this hypothesis was confirmed, we should therefore re-think our interpretation of the evolution of the Arthropoda, where terrestrialization may have led to the acquisition of similar anatomical features by convergence. At the same time, the disagreement between reconstructions based on morphological, nuclear and mitochondrial data sets seems to remain, despite the use of larger data sets and more powerful analytical methods.