The 'Peripatos' in Eurogondwana? - Lack of evidence that south-east Asian onychophorans walked through Europe
The 'Peripatos' in Eurogondwana? - Lack of evidence that south-east Asian onychophorans walked through Europe
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DOI：
10.1071/is18007
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发表时间：
2018-01-01
影响因子：
2.2
通讯作者：
Pinto-da-Rocha, Ricardo
中科院分区：
文献类型：
--
作者：
Giribet, Gonzalo;Buckman-Young, Rebecca S.;Pinto-da-Rocha, Ricardo
绒虫是一种神秘但极具魅力的陆生无脊椎动物，经常成为有趣的生物地理学辩论的主题。尽管有很大的兴趣，但由于其广泛的地理分布，样品的缺乏和具有挑战性的分子组成，一个很好的解决和完整的类群系统发育和可靠的时间表一直难以捉摸。在这里，我们提出了一个Onychophora的分子系统发育分析，包括以前未采样和未充分采样的谱系，我们使用一系列嵌套的分类单元集来分析扩展的数据集，旨在增加特定亚支系的可用信息量。这些数据集包括一个外群数据集，一个限制于群内分类群，另外三个用于新热带围蝶科、围蝶科和新围蝶科（=新热带围蝶科）。为了探索竞争的生物地理情景，我们使用少数可用的可靠化石作为校准点，生成了一个新的爪龙时间树。将我们的结果与Cyphophthalmi的结果进行比较，我们重新考虑了天鹅绒蠕虫通过Eurogondwana到达东南亚的假设，并得出结论，更有可能的情况是它们通过Sibumasu地形漂流到达东南亚。我们的系统发育结果支持两个科的相互单系性，以及两个科的东、西冈瓦纳的早期划分，每个科在二叠纪和侏罗纪之间开始多样化。与南美南部（智利）相比，paraperipatae明显支持南非的paraphyly，并且东南亚/新几内亚的Paraperipatus与澳大利亚/新西兰分类群有姐妹群关系。后者包括一个在西澳大利亚和东澳大利亚之间的分支，以及跨塔斯曼物种的两个姐妹分支（一个是卵生的，一个是胎生的）。这一模式清楚地表明，绒虫的卵细胞是继发的。Peripatidae在东南亚的Eoperipatus和西冈瓦南分支之间发现了姐妹群关系，后者分为非洲的Mesoperipatus和Neopatida。后者显示了太平洋Oroperipatus（尽管尚不清楚它们是一个还是两个分支）和一个姊妹分支之间的分裂，该分支包括Peripatus属，Epiperipatus属，Macroperipatus属的成员以及单型属Cerradopatus， Plicatoperipatus和Principapillatus的代表。但是，Peripatus、Epiperipatus和Macroperipatus不是单系的，单系属的所有种都与地理上接近的种有亲缘关系。Macroperipatus的模式种（来自特立尼达，是其他特立尼达和多巴哥的Epiperipatus物种的姐妹群）和Epiperipatus（来自法属圭亚那，与其他圭亚那的Epiperipatus和Peripatus盾形物种有亲缘关系）也是如此。Neopatida的地理结构在很大程度上被一个未解决的主干所掩盖，但许多得到很好支持的非单系的属类实例挑战了当前的分类框架，该框架通常依赖于未经系统发育测试的解剖特征。
Onychophorans, or velvet worms, are cryptic but extremely charismatic terrestrial invertebrates that have often been the subject of interesting biogeographic debate. Despite great interest, a well resolved and complete phylogeny of the group and a reliable chronogram have been elusive due to their broad geographic distribution, paucity of samples, and challenging molecular composition. Here we present a molecular phylogenetic analysis of Onychophora that includes previously unsampled and undersampled lineages and we analyse the expanded dataset using a series of nested taxon sets designed to increase the amount of information available for particular subclades. These include a dataset with outgroups, one restricted to the ingroup taxa, and three others for Peripatopsidae, Peripatidae and Neopatida (= the Neotropical Peripatidae). To explore competing biogeographic scenarios we generate a new time tree for Onychophora using the few available reliable fossils as calibration points. Comparing our results to those of Cyphophthalmi, we reconsider the hypothesis that velvet worms reached Southeast Asia via Eurogondwana, and conclude that a more likely scenario is that they reached Southeast Asia by rafting on the Sibumasu terrane. Our phylogenetic results support the reciprocal monophyly of both families as well as an early division between East and West Gondwana, also in both families, each beginning to diversify between the Permian and the Jurassic. Peripatopsidae clearly supports paraphyly of South Africa with respect to southern South America (Chile) and a sister group relationship of the Southeast Asian/New Guinean Paraperipatus to the Australian/New Zealand taxa. The latter includes a clade that divides between Western Australia and Eastern Australia and two sister clades of trans-Tasman species (one oviparous and one viviparous). This pattern clearly shows that oviparity is secondarily derived in velvet worms. Peripatidae finds a sister group relationship between the Southeast Asian Eoperipatus and the West Gondwanan clade, which divides into the African Mesoperipatus and Neopatida. The latter shows a well supported split between the Pacific Oroperipatus (although it is unclear whether they form one or two clades) and a sister clade that includes the members of the genera Peripatus, Epiperipatus, Macroperipatus and representatives of the monotypic genera Cerradopatus, Plicatoperipatus and Principapillatus. However, Peripatus, Epiperipatus and Macroperipatus are not monophyletic, and all the species from the monotypic genera are related to geographically close species. The same goes for the type species of Macroperipatus (from Trinidad, and sister group to other Trinidad and Tobago species of Epiperipatus) and Epiperipatus (from French Guiana, and related to other Guyana shield species of Epiperipatus and Peripatus). Geographic structure within Neopatida is largely obscured by an unresolved backbone, but many well supported instances of generic non-monophyly challenge the current taxonomic framework, which has often relied on anatomical characters that are untested phylogenetically.