Zoological Research Museum Alexander Koenig, Statistical Phylogenetics and Phylogenomics, Adenauerallee 160, D-53113 Bonn, Germany; Faculty of Mathematics and Natural Sciences, University of Bonn, D-53012 Bonn, Germany.
Aquatic Ecosystem Research, Faculty of Biology, University of Duisburg-Essen, Universitätsstr. 5, D-45141 Essen, Germany.
Mol Phylogenet Evol. 2019 Jul;136:206-214. doi: 10.1016/j.ympev.2019.04.017. Epub 2019 Apr 16.
Sea spiders (Pycnogonida) constitute a group of marine benthic arthropods that has a particularly high species diversity in the Southern Ocean. The "longitarsal" group of the sea spider family Colossendeidae is especially abundant in this region. However, this group also includes some representatives from other oceans, which raises the question where the group originates from. Therefore, we here investigated the phylogeny of the group with a hybrid enrichment approach that yielded a dataset of 1607 genes and over one million base pairs. We obtained a well-resolved phylogeny of the group, which is mostly consistent with morphological data. The data support an Antarctic origin of the longitarsal Colossendeidae and multiple dispersal events to other regions, which occurred at different timescales. This scenario is consistent with evidence found in other groups of marine invertebrates and highlights the role of the Southern Ocean as a source for non-Antarctic biota, especially of the deep sea. Our results suggest an initially slow rate of diversification followed by a more rapid radiation possibly correlated with the mid-Miocene cooling of Antarctica, similar to what is found in other taxa.
海蜘蛛（Pycnogonida）是一类生活在海洋底层的节肢动物，在南大洋中具有特别高的物种多样性。海蜘蛛科 Colossendeidae 的“长跗节”组在该地区特别丰富。然而，该组还包括来自其他海洋的一些代表，这就提出了该组起源于何处的问题。因此，我们在这里采用混合富集方法研究了该组的系统发育，该方法产生了一个包含 1607 个基因和超过 100 万个碱基对的数据集。我们得到了一个很好解决的组系统发育，它与形态学数据基本一致。这些数据支持长跗节 Colossendeidae 起源于南极，并多次向其他地区扩散，这些扩散事件发生在不同的时间尺度上。这种情况与在其他海洋无脊椎动物群中发现的证据一致，突出了南大洋作为非南极生物群，特别是深海生物群的来源的作用。我们的结果表明，最初的多样化速度较慢，随后是更快速的辐射，这可能与中中新世南极洲的冷却有关，与其他分类群的情况相似。
