A Phylogenomic Solution to the Origin of Insects by Resolving Crustacean-Hexapod Relationships
A Phylogenomic Solution to the Origin of Insects by Resolving Crustacean-Hexapod Relationships
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DOI：
10.1016/j.cub.2017.05.040
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发表时间：
2017-06-19
期刊：
影响因子：
9.2
通讯作者：
Giribet, Gonzalo
中科院分区：
文献类型：
--
作者：
Schwentner, Martin;Combosch, David J.;Giribet, Gonzalo
昆虫是生物体中最多样化的群体，它们嵌套在甲壳类动物中，甲壳类动物可以说是海洋动物中最丰富的群体。然而，到目前为止，还没有达成共识，甲壳类分类单元是最接近的亲属六足动物。大多数研究提出，鳃足类（例如，仙女虾）是六足类的姐妹类群[1-7]。然而，这些研究在很大程度上排除了两个同样重要的分类群，Remipedia和Ceatrocarida。其他研究表明Remipedia [8-11]或Remipedia+Cephalocarida[12，13]是六足动物的潜在姐妹群，但它们要么不包括Cephalocarida，要么只使用了桑格序列数据和形态[9，12]。在这里，我们提出了第一个基因组学研究，专门解决的起源，六足动物，包括转录组的两个物种，每一个Cephalocarida和Remipedia。对所选基质的系统发育分析，范围从81到1，675个正群和高达510，982个氨基酸位置，明确拒绝了六足动物和鳃足动物之间的姐妹群关系[1-7]。尽管如此，支持六足动物姐妹集团关系Remipedia或Cephalocarida-Remipedia是高度依赖于所采用的分析方法。进一步的分析评估基因进化率和有针对性的分类单元排除的影响，支持Remipedia作为唯一的姐妹分类单元的六足类，并建议，以前的分组Remipedia + Ceatrocarida是一个人工制品，可能是由于长分支的吸引力和成分的异质性。我们进一步得出结论，六足类的陆生化可能发生在寒武纪晚期到奥陶纪早期，这一估计与它们提出的姐妹群无关[4，8，12，14]。
Insects, the most diverse group of organisms, are nested within crustaceans, arguably the most abundant group of marine animals. However, to date, no consensus has been reached as to which crustacean taxon is the closest relative of hexapods. A majority of studies have proposed that Branchiopoda (e.g., fairy shrimps) is the sister group of Hexapoda [1-7]. However, these investigations largely excluded two equally important taxa, Remipedia and Cephalocarida. Other studies suggested Remipedia [8-11] or Remipedia+Cephalocarida[12, 13] aspotential sister groups of hexapods, but they either did not include Cephalocarida or used only Sanger sequence data and morphology [9, 12]. Here we present the first phylogenomic study specifically addressing the origins of hexapods, including transcriptomes for two species each of Cephalocarida and Remipedia. Phylogenetic analyses of selected matrices, ranging from 81 to 1,675 orthogroups and up to 510,982 amino acid positions, clearly reject a sister-group relationship between Hexapoda and Branchiopoda [1-7]. Nonetheless, support for a hexapod sister-group relationship to Remipedia or to Cephalocarida-Remipedia was highly dependent on the employed analytical methodology. Further analyses assessing the effects of gene evolutionary rate and targeted taxon exclusion support Remipedia as the sole sister taxon of Hexapoda and suggest that the prior grouping of Remipedia + Cephalocarida is an artifact, possibly due to long branch attraction and compositional heterogeneity. We further conclude that terrestrialization of Hexapoda probably occurred in the late Cambrian to early Ordovician, an estimate that is independent of their proposed sister group [4, 8, 12, 14].