Despite significant advances in invertebrate phylogenomics over the past decade, the higher-level phylogeny of Pycnogonida (sea spiders) remains elusive. Due to the inaccessibility of some small-bodied lineages, few phylogenetic studies have sampled all sea spider families. Previous efforts based on a handful of genes have yielded unstable tree topologies. Here, we inferred the relationships of 89 sea spider species using targeted capture of the mitochondrial genome, 56 conserved exons, 101 ultraconserved elements, and three nuclear ribosomal genes. We inferred molecular divergence times by integrating morphological data for fossil species to calibrate 15 nodes in the arthropod tree of life. This integration of data classes resolved the basal topology of sea spiders with high support. The enigmatic family Austrodecidae was resolved as the sister group to the remaining Pycnogonida and the small-bodied family Rhynchothoracidae as the sister group of the robust-bodied family Pycnogonidae. Molecular divergence time estimation recovered a basal divergence of crown group sea spiders in the Ordovician. Comparison of diversification dynamics with other marine invertebrate taxa that originated in the Paleozoic suggests that sea spiders and some crustacean groups exhibit resilience to mass extinction episodes, relative to mollusk and echinoderm lineages.

中文翻译：

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通过整合多个数据类来解决海蜘蛛多样化的系统基因组学问题。


尽管过去十年无脊椎动物系统发育学取得了重大进展，但海蜘蛛的高级系统发育仍然难以捉摸。由于一些体型较小的谱系难以接近，很少有系统发育研究对所有海蜘蛛科进行了采样。之前基于少数基因的努力已经产生了不稳定的树拓扑。在这里，我们通过靶向捕获线粒体基因组、56 个保守外显子、101 个超保守元件和 3 个核核糖体基因，推断了 89 个海蜘蛛物种的关系。我们通过整合化石物种的形态数据来校准节肢动物生命树中的 15 个节点，从而推断出分子分歧时间。这种数据类的集成解决了具有高支持度的海蜘蛛的基础拓扑。神秘的Austrodecidae科被确定为其余Pycnogonidae科的姐妹群，而体型较小的Rhynchothoracidae科则被确定为体型健壮的Pycnogonidae科的姐妹群。分子分歧时间估计恢复了奥陶纪冠群海蜘蛛的基本分歧。与起源于古生代的其他海洋无脊椎动物类群的多样化动态比较表明，相对于软体动物和棘皮动物谱系，海蜘蛛和一些甲壳类动物表现出对大规模灭绝事件的恢复能力。