Bargelloni L, Ritchie P A, Patarnello T, Battaglia B, Lambert D M, Meyer A
Department of Ecology and Evolution, State University of New York, Stony Brook.
Mol Biol Evol. 1994 Nov;11(6):854-63. doi: 10.1093/oxfordjournals.molbev.a040168.
Most fishes of the perciform suborder Notothenioidei are endemic to the subzero marine waters of Antarctica. A number of remarkable physiological attributes allow them to inhabit this extreme environment; for example, the blood of almost all notothenioid species contains antifreeze glycopeptides. To establish a molecular phylogenetic hypothesis for these fishes, DNA sequences from two mitochondrial genes, portions of the 12S and 16S ribosomal genes (928 base pairs [bp]), were determined for 18 species. These belong to 15 genera in five families of the suborder. The DNA data suggest that two of these families are unnatural groups and consequently that the classification and phylogeny of this suborder is in need of revision. In terms of DNA variation, the Bovichtidae are a distantly related sister group to the other families of the suborder that includes the icefishes, the only vertebrates without hemoglobin. The fishes of the suborder (except the Bovichtidae) seem to have speciated rapidly, forming an adaptive radiation in the Antarctic waters. A phylogenetic analysis of published hemoglobin amino acid sequences for other notothenioid fishes supports these results from mtDNA. On the basis of molecular phylogeny, the evolution of antifreeze glycopeptides was studied. The age of the radiation of notothenioid fishes had been estimated to be at least 38 Mya. However, the level of mtDNA variation detected in notothenioid fishes appears to be too low to agree with this date of origin and might instead suggest a younger age (10-15 Mya). Alternatively, the low level of detected mtDNA variation would agree with the traditional old-age estimate if an extremely slow rate of mtDNA evolution is postulated for this group. This slow-rate hypothesis, if true, could be explained by decreased metabolic rates slowing down the tempo of molecular evolution.
鲈形亚目南极鱼亚目的大多数鱼类是南极洲亚零度海水中的特有物种。许多显著的生理特性使它们能够栖息在这种极端环境中；例如，几乎所有南极鱼亚目物种的血液中都含有抗冻糖肽。为了建立这些鱼类的分子系统发育假说，测定了18个物种的两个线粒体基因（12S和16S核糖体基因部分，共928个碱基对[bp]）的DNA序列。这些物种属于该亚目五个科的15个属。DNA数据表明，其中两个科是不自然的类群，因此该亚目的分类和系统发育需要修订。就DNA变异而言，三刺南极鱼科是与该亚目其他科关系较远的姐妹类群，其他科包括冰鱼，冰鱼是唯一没有血红蛋白的脊椎动物。该亚目的鱼类（除三刺南极鱼科外）似乎迅速分化，在南极水域形成了适应性辐射。对已发表的其他南极鱼亚目鱼类血红蛋白氨基酸序列的系统发育分析支持了线粒体DNA的这些结果。基于分子系统发育，对抗冻糖肽的进化进行了研究。南极鱼亚目鱼类辐射的时间估计至少为3800万年前。然而，在南极鱼亚目鱼类中检测到的线粒体DNA变异水平似乎过低，与这个起源时间不一致，反而可能表明时间更近（1000 - 1500万年前）。或者，如果假定该类群线粒体DNA进化速度极慢，那么检测到的低水平线粒体DNA变异就与传统的古老估计一致。如果这个慢进化速度假说成立，可以用代谢率降低减缓分子进化速度来解释。
