DataSheet_1_Unraveling the phylogeny of Chaetopteridae (Annelida) through mitochondrial genome analysis.xlsx

Mitochondrial genomes serve as valuable markers for phylogenetic and evolutionary studies across diverse invertebrate taxa, but their application within Annelida remains limited. In this study, we report the mitochondrial genomes of seven species from four genera of Chaetopteridae (Annelida), obtained by high-throughput sequencing. Phylogenetic analysis was performed using cox1, 18S, 28S and all mitochondrial genes. Our results reveal Chaetopterus and Mesochaetopterus as well-supported monophyletic sister clades, while Phyllochaetopterus and Spiochaetopterus appear paraphyletic, with species from both genera in a mixed clade sister to Chaetopterus + Mesochaetopterus. While mitochondrial gene orders remain conserved within Chaetopteridae, they appear substantially different from those of the ancestral patterns in Annelida. All 13 protein-coding genes found in Chaetopteridae evolved under strong purification selection, although Phyllochaetopterus exhibited the highest base-substitution rate for most of them, suggesting a more relaxed purified selection. Overall, our study provides molecular resources for phylogenetic studies of Chaetopteridae, highlighting the necessity for a comprehensive revision of the family, particularly dealing with the paraphyletic Phyllochaetopterus and Spiochaetopterus.

线粒体基因组（mitochondrial genomes）是多样无脊椎动物类群系统发育与进化研究的重要分子标记，但该类标记在环节动物门（Annelida）中的应用仍较为有限。本研究通过高通量测序技术，获得了环节动物门帚毛虫科（Chaetopteridae）4个属共计7个物种的线粒体基因组序列并进行了报道。本研究采用cox1基因、18S核糖体RNA基因、28S核糖体RNA基因以及全部线粒体基因开展系统发育分析。研究结果显示，帚毛虫属（Chaetopterus）与中帚毛虫属（Mesochaetopterus）为支持度较高的单系姊妹支；而叶帚毛虫属（Phyllochaetopterus）和刺帚毛虫属（Spiochaetopterus）则呈并系特征，两属物种共同构成一个混合支系，该支系与帚毛虫属+中帚毛虫属构成姊妹支关系。尽管帚毛虫科内部的线粒体基因排列较为保守，但该科的线粒体基因排列模式与环节动物门的祖先模式存在显著差异。帚毛虫科所包含的全部13个蛋白质编码基因均经历了强烈的纯化选择，但叶帚毛虫属的多数蛋白质编码基因碱基替换率最高，提示其纯化选择压力更为宽松。综上，本研究为帚毛虫科的系统发育研究提供了分子数据资源，同时强调了对该科开展全面分类修订的必要性，尤其是针对并系的叶帚毛虫属和刺帚毛虫属。