Molecular evidence for the monophyly of flatfishes (Carangimorpharia: Pleuronectiformes)

Proliferation of phylogenetic studies based on poor taxonomic sampling or insufficient molecular evidence usually leads to conflicting results. As a consequence, advancement of systematic knowledge yields to confusion. The problem is exacerbated for taxonomic groups with historically difficult resolution of evolutionary relationships such as the flatfishes. Molecular evidence to support monophyly for this emblematic group of fishes and their interrelationships has been elusive, and a recent paper published in this journal went as far as to claim that flatfish monophyly can be rejected with molecular data, implying that the asymmetric body plan unique to these fishes had two independent origins. A reanalysis of this evidence suggests the contrary and combination of the new data with existing datasets unequivocally supports the monophyly of this group based on analyses of concatenated data as well as species tree approaches. Resolution of difficult phylogenetic problems requires analysis ...基于分类取样不足或分子证据匮乏的系统发育（phylogenetic）研究数量激增，往往会得到相互矛盾的结果。由此一来，本应取得进展的系统分类学认知反而陷入混乱。这一问题在演化关系长期难以解析的类群中尤为凸显，比目鱼（flatfishes）正是这类类群的典型代表。长期以来，支撑这类极具代表性鱼类单系（monophyly）性及其内部演化关系的分子证据始终稀缺，近期发表于本期刊的一篇论文甚至提出，可借助分子数据否定比目鱼的单系性，这意味着这类鱼类独有的不对称体型结构曾经历两次独立起源。本研究对上述证据的重新分析得出了相反结论，将新数据与现有数据集整合后，无论是基于拼接序列数据的分析还是物种树（species tree）方法，均明确支持该类群的单系性。疑难系统发育问题的解析离不开……