Inoue Jun G, Kumazawa Yoshinori, Miya Masaki, Nishida Mutsumi
Ocean Research Institute, University of Tokyo, Tokyo, Japan.
Mol Phylogenet Evol. 2009 Jun;51(3):486-99. doi: 10.1016/j.ympev.2009.01.020.
The continental distributions of freshwater fishes in the family Notopteridae (Osteoglossomorpha) across Africa, India, and Southeast Asia constitute a long standing and enigmatic problem of freshwater biogeography. The migrational pathway of the Asian notopterids has been discussed in light of two competing schemes: the first posits recent transcontinental dispersal while the second relies on distributions being shaped by ancient vicariance associated with plate-tectonic events. In this study, we determined complete mitochondrial DNA sequences from 10 osteoglossomorph fishes to estimate phylogenetic relationships using partitioned Bayesian and maximum likelihood methods and divergence dates of the family Notopteridae with a partitioned Bayesian approach. We used six species representing the major lineages of the Notopteridae and seven species from the remaining osteoglossomorph families. Fourteen more-derived teleosts, nine basal actinopterygians, two coelacanths, and one shark were used as outgroups. Phylogenetic analyses indicated that the African and Asian notopterids formed a sister group to each other and that these notopterids were a sister to a clade comprising two African families (Mormyridae and Gymnarchidae). Estimated divergence time between the African and Asian notopterids dated back to the early Cretaceous when India-Madagascar separated from the African part of Gondwanaland. Thus, estimated time of divergence based on the molecular evidence is at odds with the recent dispersal model. It can be reconciled with the geological and paleontological evidence to support the vicariance model in which the Asian notopterids diverged from the African notopterids in Gondwanaland and migrated into Eurasia on the Indian subcontinent from the Cretaceous to the Tertiary. However, we could not exclude an alternative explanation that the African and Asian notopterids diverged in Pangea before its complete separation into Laurasia and Gondwanaland, to which these two lineages were later confined, respectively.
骨舌鱼目弓背鱼科淡水鱼在非洲、印度和东南亚的大陆分布，构成了淡水生物地理学中一个长期存在且令人费解的问题。亚洲弓背鱼科鱼类的迁移路径一直根据两种相互竞争的模式进行讨论：第一种模式假定是近期的跨大陆扩散，而第二种模式则认为其分布是由与板块构造事件相关的古代地理隔离所塑造的。在本研究中，我们测定了10种骨舌鱼目的完整线粒体DNA序列，使用分区贝叶斯法和最大似然法来估计系统发育关系，并采用分区贝叶斯方法确定弓背鱼科的分歧时间。我们使用了代表弓背鱼科主要谱系的6个物种，以及来自其余骨舌鱼目科的7个物种。另外还使用了14种更进化的硬骨鱼、9种基干辐鳍鱼、2种腔棘鱼和1种鲨鱼作为外类群。系统发育分析表明，非洲和亚洲的弓背鱼科鱼类彼此形成姐妹群，并且这些弓背鱼科鱼类是一个包含两个非洲科（长颌鱼科和裸臀鱼科）的进化枝的姐妹。非洲和亚洲弓背鱼科鱼类之间的估计分歧时间可追溯到早白垩世，当时印度 - 马达加斯加从冈瓦纳大陆的非洲部分分离出来。因此，基于分子证据估计的分歧时间与近期扩散模型不一致。它可以与地质和古生物学证据相协调，以支持地理隔离模型，即亚洲弓背鱼科鱼类在冈瓦纳大陆与非洲弓背鱼科鱼类分歧，并在白垩纪至第三纪期间从印度次大陆迁移到欧亚大陆。然而，我们不能排除另一种解释，即非洲和亚洲弓背鱼科鱼类在泛大陆完全分裂为劳亚大陆和冈瓦纳大陆之前就已经分歧，这两个谱系后来分别局限于这两个大陆。
