生物
谱系(遗传)
姐妹团
进化生物学
系统发育学
分类单元
系统基因组学
门
背景(考古学)
双壳类
系统发育树
古生物学
生物多样性
动物
分子钟
软体动物
生态学
克莱德
遗传学
基因
细菌
作者
Hao Song,Y. P. Wang,Haojing Shao,Zhuoqing Li,Pan Hu,Meghan K. Yap-Chiongco,Ping Shi,Tao Zhang,Cui Li,Yiguan Wang,Peizhen Ma,Jakob Vinther,Haiyan Wang,Kevin M. Kocot
标识
DOI:10.1073/pnas.2302361120
摘要
The almost simultaneous emergence of major animal phyla during the early Cambrian shaped modern animal biodiversity. Reconstructing evolutionary relationships among such closely spaced branches in the animal tree of life has proven to be a major challenge, hindering understanding of early animal evolution and the fossil record. This is particularly true in the species-rich and highly varied Mollusca where dramatic inconsistency among paleontological, morphological, and molecular evidence has led to a long-standing debate about the group’s phylogeny and the nature of dozens of enigmatic fossil taxa. A critical step needed to overcome this issue is to supplement available genomic data, which is plentiful for well-studied lineages, with genomes from rare but key lineages, such as Scaphopoda. Here, by presenting chromosome-level genomes from both extant scaphopod orders and leveraging complete genomes spanning Mollusca, we provide strong support for Scaphopoda as the sister taxon of Bivalvia, revitalizing the morphology-based Diasoma hypothesis originally proposed 50 years ago. Our molecular clock analysis confidently dates the split between Bivalvia and Scaphopoda at ~520 Ma, prompting a reinterpretation of controversial laterally compressed Early Cambrian fossils, including Anabarella , Watsonella, and Mellopegma, as stem diasomes. Moreover, we show that incongruence in the phylogenetic placement of Scaphopoda in previous phylogenomic studies was due to ancient incomplete lineage sorting (ILS) that occurred during the rapid radiation of Conchifera. Our findings highlight the need to consider ILS as a potential source of error in deep phylogeny reconstruction, especially in the context of the unique nature of the Cambrian Explosion.
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