Hunt D M, Fitzgibbon J, Slobodyanyuk S J, Bowmaker J K, Dulai K S
Department of Molecular Genetics, University College London, United Kingdom.
Mol Phylogenet Evol. 1997 Dec;8(3):415-22. doi: 10.1006/mpev.1997.0428.
Lake Baikal in Eastern Siberia contains a remarkable flock of 29 species of teleost fishes of the suborder Cottoidei (sculpins, bullheads) that are endemic to the lake and its associated rivers and occupy all depth habitats down to over 1500 m. The species are divided into three families, the Cottidae with 7 species, the Abyssocottidae with 20 species, and the Comephoridae with 2 species. Nucleotide sequences of the rod opsin gene from 12 of these species, plus a non-Baikal marine species, have been used to examine the evolutionary relations and the divergence time of the flock. Phylogenetic trees, generated by neighbor-joining and maximum parsimony, indicate that the unique Comephoridae family with its viviparity and unusual appearance is closely related to the Cottidae and Abyssocottidae, whereas the genus Cottocomephorus, at present placed in the Cottidae, was the first to diverge from the ancestral species and forms a separate lineage. The major adaptation to deep water would appear to be of relatively recent origin, and there is evidence that the ancestral species occupied a shallow-water-marine or brackish habitat. Estimates of antiquity obtained from synonymous substitutions place the origin of the species flock at around 4.9 million years ago.
位于西伯利亚东部的贝加尔湖拥有一群引人注目的29种鲈形目杜父鱼亚目（杜父鱼、大头鱼）鱼类，它们是该湖及其相关河流的特有物种，占据了从浅水区到超过1500米深处的所有深度栖息地。这些物种分为三个科，杜父鱼科有7种，深海杜父鱼科有20种，贝加尔湖胎生杜父鱼科有2种。已使用其中12个物种以及一种非贝加尔湖海洋物种的视杆视蛋白基因的核苷酸序列来研究该鱼类群的进化关系和分歧时间。通过邻接法和最大简约法生成的系统发育树表明，具有胎生和独特外观的独特贝加尔湖胎生杜父鱼科与杜父鱼科和深海杜父鱼科密切相关，而目前归入杜父鱼科的贝湖杜父鱼属是最早从祖先物种分化出来的，并形成了一个单独的谱系。对深水的主要适应似乎起源相对较晚，并且有证据表明祖先物种占据了浅海或咸淡水栖息地。从同义替换获得的古老性估计表明该物种群的起源约在490万年前。
