Inoue Jun G, Miya Masaki, Tsukamoto Katsumi, Nishida Mutsumi
Ocean Research Institute, University of Tokyo, 1-15-1 Minamidai, Nakano-ku, Tokyo 164-8639, Japan.
Mol Phylogenet Evol. 2004 Jul;32(1):274-86. doi: 10.1016/j.ympev.2003.11.009.
The monophyly of Elopomorpha (eels and their relatives) has long been one of the most problematic issues in systematic ichthyology. Since established the Elopomorpha based on the existence of the leaf-like larval form, termed a leptocephalus, no one has corroborated their monophyly using character matrices derived from both morphological and molecular data during the last 30 years. We investigated their monophyly and interrelationships at the ordinal level using complete mitochondrial genomic (mitogenomic) data from 33 purposefully chosen species (data for nine species being newly determined during the study) that fully represent the major teleostean and elopomorph lineages. Partitioned Bayesian analyses were conducted with the two data sets that comprised concatenated nucleotide sequences from 12 protein-coding genes (with and without third codon positions), 22 transfer RNA genes, and two ribosomal RNA genes. The resultant trees were well resolved and largely congruent, with most internal branches being supported by high statistical values. Mitogenomic data strongly supported the monophyly of Elopomorpha, indicating the validity of the leptocephalus as an elopomorph synapomorphy. The order Elopiformes occupied the most basal position in the elopomorph phylogeny, with the Albuliformes and a clade comprising the Anguilliformes and the Saccopharyngiformes forming a sister group. The most parsimonious reconstruction of the three previously recognized, distinct larval types of elopomorphs onto the molecular phylogeny revealed that one of the types (fork-tailed type) had originated as the common ancestor of the Elopomorpha, the other two (filament-tailed and round-tailed types) having diversified separately in two more derived major clades.
海鳗总目(鳗鱼及其近亲)的单系性长期以来一直是系统鱼类学中最具争议的问题之一。自从基于叶状幼体形态(称为柳叶状幼体)的存在确立了海鳗总目以来,在过去30年里,没有人利用形态学和分子数据得出的特征矩阵来证实它们的单系性。我们使用了33个特意挑选的物种的完整线粒体基因组(线粒体基因组)数据(其中9个物种的数据是在研究过程中新测定的)来研究它们在目级水平上的单系性和相互关系,这些物种充分代表了主要的硬骨鱼系和海鳗总目谱系。对两个数据集进行了分区贝叶斯分析,这两个数据集由12个蛋白质编码基因(有和没有第三密码子位置)、22个转运RNA基因和两个核糖体RNA基因的串联核苷酸序列组成。得到的树解析良好且基本一致,大多数内部分支得到了高统计值的支持。线粒体基因组数据有力地支持了海鳗总目的单系性,表明柳叶状幼体作为海鳗总目共衍征的有效性。海鳗目在海鳗总目系统发育中占据最基部的位置,北梭鱼目和一个由鳗鲡目和囊咽鱼目组成的分支形成一个姐妹群。在分子系统发育树上对三种先前公认的、不同的海鳗总目幼体类型进行的最简约重建显示,其中一种类型(叉尾型)起源于海鳗总目的共同祖先,另外两种类型(丝尾型和圆尾型)在另外两个衍生的主要分支中分别分化。