The molluscan order Neogastropoda encompasses over 15,000 almost exclusively marine species playing important roles in benthic communities and in the economies of coastal countries. Neogastropoda underwent intensive cladogenesis in early stages of diversification, generating a ‘bush’ at the base of their evolutionary tree, that has been hard to resolve even with high throughput molecular data. In the present study to resolve the bush, we use a variety of phylogenetic inference methods and a comprehensive exon capture dataset of 1,817 loci (79.6% data occupancy) comprising 112 taxa of 48 out of 60 Neogastropoda families. Our results show consistent topologies and high support in all analyses at (super)family level, supporting monophyly of Muricoidea, Mitroidea, Conoidea, and, with some reservations, Olivoidea and Buccinoidea. Volutoidea and Turbinelloidea as currently circumscribed are clearly paraphyletic. Despite our analyses consistently resolving most backbone nodes, three prove problematic: First, uncertain placement of Cancellariidae, as the sister group to either a Ficoidea-Tonnoidea clade, or to the rest of Neogastropoda, leaves monophyly of Neogastropoda unresolved. Second, relationships are contradictory at the base of the major ‘core Neogastropoda’ grouping. Third, coalescence-based analyses reject monophyly of the Buccinoidea in relation to Vasidae. We analysed phylogenetic signal of targeted loci in relation to potential biases, and we propose most probable resolutions in the latter two recalcitrant nodes. The uncertain placement of Cancellariidae may be explained by orthology violations due to differential paralog loss shortly after the whole genome duplication, which should be resolved with a curated set of longer loci.

中文翻译：

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新腹足动物的系统发育学：隐藏在灌木丛中的骨干


新腹足纲软体动物目包含超过 15,000 种几乎完全是海洋物种，它们在底栖群落和沿海国家的经济中发挥着重要作用。新腹足纲在多样化的早期阶段经历了密集的分支形成，在其进化树的底部产生了一个“灌木丛”，即使使用高通量的分子数据也很难解决这一问题。在本研究中，为了解决灌木丛问题，我们使用了多种系统发育推断方法和包含 1,817 个位点（79.6% 数据占用率）的综合外显子捕获数据集，其中包括 60 个新腹足纲科中的 48 个科的 112 个分类单元。我们的结果显示在（超）科水平的所有分析中具有一致的拓扑和高度支持，支持 Muricoidea、Mitroidea、Conoidea 的单系性，以及（有一些保留）Olivoidea 和 Buccinoidea 的单系性。目前所界定的Volutoidea 和Turbinelloidea 显然是并系的。尽管我们的分析一致地解决了大多数骨干节点，但三个问题被证明是有问题的：首先，Cancellariidae作为Ficoidea-Tonnoidea分支或新腹足纲其余部分的姐妹群的位置不确定，导致新腹足纲的单系性未得到解决。其次，在主要的“核心新腹足纲”群体的基础上，关系是矛盾的。第三，基于合并的分析拒绝了 Buccinoidea 与 Vasidae 相关的单系。我们分析了与潜在偏差相关的目标位点的系统发育信号，并在后两个顽固节点中提出了最可能的解决方案。 Cancellariidae 的不确定位置可能是由于全基因组复制后不久，由于不同的旁系同源丢失而导致直系同源违规，这应该通过一组更长的基因座来解决。