Data from: 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 of larger datasets with adequate taxonomic coverage and sound hypothesis-testing procedures. Proliferation of partial studies claiming extraordinary results should be avoided in order to advance the field of molecular phylogenetics.基于欠充分分类采样或分子证据不足的系统发育研究日益增多，往往会得出相互矛盾的结果。在此情况下，系统分类学知识的进步反而陷入混乱。对于进化关系长期难以厘清的类群——比如比目鱼（flatfishes）——这一问题尤为突出。支持这类标志性鱼类单系群（monophyly）及其内部亲缘关系的分子证据始终难以获取，近期发表于该期刊的一篇论文甚至提出，可利用分子数据否定比目鱼的单系性，这意味着这类鱼类特有的不对称体型结构曾独立起源两次。对该证据的重新分析则得出相反结论：将新数据与现有数据集整合后，无论是基于串联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。解决复杂的系统发育难题，需要采用具备充足分类覆盖度的大规模数据集，并辅以严谨的假说检验流程。为推动分子系统发育学领域的发展，应避免涌现大量仅依据局部研究便宣称突破性结论的成果。