The phylogenetic relationships within the molluscan class Polyplacophora (chitons) have been studied using morphology, traditional Sanger markers and mitogenomics, but, to date, no analysis has been carried out using transcriptomic and genome-wide data. Here, we leverage the power of transcriptomes to investigate the chiton phylogeny to test current classification schemes and the position of Callochitonidae, a family whose phylogenetic position and taxonomic assignation are uncertain because of conflicting results from past studies. Using multiple data matrices with different taxon occupancy thresholds and inference methods, including both concatenated and coalescence-based approaches, we find a consistent resolution of the chiton phylogeny. Our results support a system with the orders Lepidopleurida, Chitonida and Callochitonida, with the latter two as sister groups. This resolution is compatible with recent mitogenomic results and rejects the position of Callochiton as a member of Chitonina.

中文翻译：

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收紧腰带：Polyplacophora的植物转录组学

已经使用形态学、传统的 Sanger 标记和有丝分裂基因组学研究了软体动物类 Polyplacophora (chitons) 内的系统发育关系，但迄今为止，尚未使用转录组学和全基因组数据进行分析。在这里，我们利用转录组的力量来研究石鳖系统发育，以测试当前的分类方案和 Callochitonidae 的位置，由于过去研究的结果相互矛盾，该科的系统发育位置和分类学分配尚不确定。使用具有不同分类单元占用阈值和推理方法的多个数据矩阵，包括连接和基于合并的方法，我们发现石鳖系统发育的一致分辨率。我们的结果支持具有鳞翅目、奇多尼达和 Callochitonida 目的系统，与后两者为姊妹组。该决议与最近的有丝分裂基因组结果兼容，并拒绝 Callochiton 作为 Chitonina 成员的立场。