Satoh Takashi P, Miya Masaki, Endo Hiromitsu, Nishida Mutsumi
Ocean Research Institute, The University of Tokyo, 1-15-1 Minamidai, Nakano-ku, Tokyo 164-8639, Japan.
Mol Phylogenet Evol. 2006 Jul;40(1):129-38. doi: 10.1016/j.ympev.2006.02.014. Epub 2006 Apr 5.
The gene order of mitochondrial genomes (mitogenomes) has been employed as a useful phylogenetic marker in various metazoan animals, because it may represent uniquely derived characters shared by members of monophyletic groups. During the course of molecular phylogenetic studies of the order Gadiformes (cods and their relatives) based on whole mitogenome sequences, we found that two deep-sea grenadiers (Squalogadus modificatus and Trachyrincus murrayi: family Macrouridae) revealed a unusually identical gene order (translocation of the tRNA(Leu (UUR))). Both are members of the same family, although their external morphologies differed so greatly (e.g., round vs. pointed head) that they have been placed in different subfamilies Macrouroidinae and Trachyrincinae, respectively. Additionally, we determined the whole mitogenome sequences of two other species, Bathygadus antrodes and Ventrifossa garmani, representing a total of four subfamilies currently recognized within Macrouridae. The latter two species also exhibited gene rearrangements, resulting in a total of three different patterns of unique gene order being observed in the four subfamilies. Partitioned Bayesian analysis was conducted using available whole mitogenome sequences from five macrourids plus five outgroups. The resultant trees clearly indicated that S. modificatus and T. murrayi formed a monophyletic group, having a sister relationship to other macrourids. Thus, monophyly of the two species with disparate head morphologies was corroborated by two different lines of evidence (nucleotide sequences and gene order). The overall topology of the present tree differed from any of the previously proposed, morphology-based phylogenetic hypotheses.
线粒体基因组（线粒体基因组）的基因顺序已被用作各种后生动物中一种有用的系统发育标记，因为它可能代表单系类群成员共有的独特衍生特征。在基于完整线粒体基因组序列对鳕形目（鳕鱼及其近亲）进行分子系统发育研究的过程中，我们发现两种深海鼠尾鳕（改良鼠尾鳕和默氏长吻鼠尾鳕：鼠尾鳕科）显示出异常相同的基因顺序（tRNA（Leu（UUR））的易位）。尽管它们的外部形态差异很大（例如，圆头与尖头），以至于它们分别被归入不同的亚科，即鼠尾鳕亚科和长吻鼠尾鳕亚科，但它们都是同一科的成员。此外，我们还测定了另外两个物种，即深海鳕和加氏腹凹鳕的完整线粒体基因组序列，这两个物种代表了目前在鼠尾鳕科中公认的四个亚科。后两个物种也表现出基因重排，导致在这四个亚科中总共观察到三种不同的独特基因顺序模式。使用来自五种鼠尾鳕加上五种外类群的可用完整线粒体基因组序列进行了分区贝叶斯分析。所得的树清楚地表明，改良鼠尾鳕和默氏长吻鼠尾鳕形成了一个单系类群，与其他鼠尾鳕具有姐妹关系。因此，通过两种不同的证据线（核苷酸序列和基因顺序）证实了这两种头部形态不同的物种的单系性。当前树的总体拓扑结构与任何先前提出的基于形态学的系统发育假设都不同。
