The Ediacaran origin of Ecdysozoa: integrating fossil and phylogenomic data
The Ediacaran origin of Ecdysozoa: integrating fossil and phylogenomic data
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DOI：
10.1144/jgs2021-107
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发表时间：
2022-03-10
影响因子：
2.7
通讯作者：
Pisani, Davide
中科院分区：
文献类型：
--
作者：
Howard, Richard J.;Giacomelli, Mattia;Pisani, Davide
蜕皮动物（节肢动物门，Kinorhyncha，Loricifera，Nematoda，Nematomorpha，Onychophora，Priapulida，Tardigrada）是无脊椎动物，具有坚韧的，定期蜕皮的角质层，使其易于保存。在早寒武世至中寒武世，蜕皮动物占主导地位，是最古老的异常保存的两侧对称动物。520-508 Ma），最晚埃迪卡拉纪（< 556 Ma）可能有遗迹化石。蜕皮动物的化石记录是主要动物分支中最好的理解之一，并被认为很好地记录了它们的起源和进化历史。然而，引人注目的是，分子钟分析暗示了蜕皮动物的前寒武纪起源要深得多，比它们最早的化石要古老得多。在这里，使用一组改进的化石校准，我们进行贝叶斯分析，估计进化时间树蜕皮动物，采样所有八门的第一次。我们的研究结果恢复Scalidophora的姐妹组Nematoida + Panarthropoda（= Cryptovermes nov.）并表明，埃迪卡拉纪的蜕皮动物的分歧发生在第一个潜在的蜕皮动物遗迹化石之前至少2300万年。这一发现是不受影响的使用所有合理的遗传学，化石先验分布，进化速率模型和矩阵分区策略。节肢动物表现出更高的精度和更少的不一致性之间的化石和时钟为基础的估计比其他蜕皮动物门的分支年龄。补充材料：所使用的全部方法和化石校准点的附录可在http：//www.example.com上查阅。专题收藏：本文是寒武纪爆炸进展收藏的一部分，可在https://www.lyellcollection.org/cc/advances-cambrian-explosion上查阅。doi.org/10.6084/m9.figshare.c.5811381
Ecdysozoans (Phyla Arthropoda, Kinorhyncha, Loricifera, Nematoda, Nematomorpha, Onychophora, Priapulida, Tardigrada) are invertebrates bearing a tough, periodically moulted cuticle that predisposes them to exceptional preservation. Ecdysozoans dominate the oldest exceptionally preserved bilaterian animal biotas in the early to mid-Cambrian (c. 520-508 Ma), with possible trace fossils in the latest Ediacaran (< 556 Ma). The fossil record of Ecdysozoa is among the best understood of major animal clades and is believed to document their origins and evolutionary history well. Strikingly, however, molecular clock analyses have implied a considerably deeper Precambrian origin for Ecdysozoa, much older than their earliest fossils. Here, using an improved set of fossil calibrations, we performed Bayesian analyses to estimate an evolutionary time-tree for Ecdysozoa, sampling all eight phyla for the first time. Our results recover Scalidophora as the sister group to Nematoida + Panarthropoda (= Cryptovermes nov.) and suggest that the Ediacaran divergence of Ecdysozoa occurred at least 23 myr before the first potential ecdysozoan trace fossils. This finding is impervious to the use of all plausible phylogenies, fossil prior distributions, evolutionary rate models and matrix partitioning strategies. Arthropods exhibit more precision and less incongruence between fossil- and clock-based estimates of clade ages than other ecdysozoan phyla. Supplementary material: Full methodologies used and an appendix of fossil calibration points are available athttps://doi.org/10.6084/m9.figshare.c.5811381 Thematic collection: This article is part of the Advances in the Cambrian Explosion collection available at:https://www.lyellcollection.org/cc/advances-cambrian-explosion.