Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520, USA.
Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK.
Mol Phylogenet Evol. 2015 Aug;89:205-18. doi: 10.1016/j.ympev.2015.04.004. Epub 2015 Apr 18.
Elopomorpha is one of the three main clades of living teleost fishes and includes a range of disparate lineages including eels, tarpons, bonefishes, and halosaurs. Elopomorphs were among the first groups of fishes investigated using Hennigian phylogenetic methods and continue to be the object of intense phylogenetic scrutiny due to their economic significance, diversity, and crucial evolutionary status as the sister group of all other teleosts. While portions of the phylogenetic backbone for Elopomorpha are consistent between studies, the relationships among Albula, Pterothrissus, Notacanthiformes, and Anguilliformes remain contentious and difficult to evaluate. This lack of phylogenetic resolution is problematic as fossil lineages are often described and placed taxonomically based on an assumed sister group relationship between Albula and Pterothrissus. In addition, phylogenetic studies using morphological data that sample elopomorph fossil lineages often do not include notacanthiform or anguilliform lineages, potentially introducing a bias toward interpreting fossils as members of the common stem of Pterothrissus and Albula. Here we provide a phylogenetic analysis of DNA sequences sampled from multiple nuclear genes that include representative taxa from Albula, Pterothrissus, Notacanthiformes and Anguilliformes. We integrate our molecular dataset with a morphological character matrix that spans both living and fossil elopomorph lineages. Our results reveal substantial uncertainty in the placement of Pterothrissus as well as all sampled fossil lineages, questioning the stability of the taxonomy of fossil Elopomorpha. However, despite topological uncertainty, our integration of fossil lineages into a Bayesian time calibrated framework provides divergence time estimates for the clade that are consistent with previously published age estimates based on the elopomorph fossil record and molecular estimates resulting from traditional node-dating methods.
鳗鲡形目是现存硬骨鱼类的三个主要分支之一，包括一系列截然不同的谱系，包括鳗鱼、海鲢、骨舌鱼和海龙目。鳗鲡形目鱼类是最早使用亨尼根系统发育方法进行研究的鱼类之一，由于其经济重要性、多样性以及作为所有其他硬骨鱼姐妹群的关键进化地位，它们仍然是系统发育研究的焦点。虽然鳗鲡形目系统发育骨干的某些部分在不同的研究中是一致的，但 Albula、Pterothrissus、Notacanthiformes 和 Anguilliformes 之间的关系仍然存在争议，难以评估。这种缺乏系统发育分辨率的问题在于，化石谱系通常是根据 Albula 和 Pterothrissus 之间假定的姐妹群关系来描述和分类的。此外，使用形态数据进行的系统发育研究，通常不包括 Notacanthiformes 或 Anguilliformes 谱系，这可能会导致将化石解释为 Pterothrissus 和 Albula 的共同祖先成员的偏见。在这里，我们提供了对从多个核基因中采样的 DNA 序列进行的系统发育分析，这些基因包括 Albula、Pterothrissus、Notacanthiformes 和 Anguilliformes 的代表类群。我们将我们的分子数据集与一个涵盖现存和化石鳗鲡形目谱系的形态特征矩阵相结合。我们的研究结果揭示了 Pterothrissus 以及所有采样的化石谱系的位置存在很大的不确定性，这对化石鳗鲡形目分类的稳定性提出了质疑。然而，尽管拓扑结构不确定，我们将化石谱系纳入贝叶斯时间校准框架为该分支提供了分歧时间估计，这些估计与基于鳗鲡形目化石记录的先前发表的年龄估计以及传统节点定年方法得出的分子估计一致。
