Molecular differentiation by PCR-RFLP technique shows that Antarctic fishes of the genus Notothenia, claimed to be two species, are phenotypic varieties with the same genetic pattern (Table 1)

The taxonomy of Antarctic fishes has been predominantly based on morphological characteristics rather than on genetic criteria. A typical example is the Notothenia group, which includes N. coriiceps Richardson, 1844, N. neglecta Nybelin, 1951 and N. rossii Richardson, 1844. The Polymerase Chain Reaction and Restriction Fragment Length Polymorphism (PCR-RFLP) technique was used to determine whether N. coriiceps Richardson, 1844 and N. neglecta Nybelin, 1951 are different or whether they are the same species with morphological, physiological and behavioural variability. N. rossii was used as control. Mitochondrial DNA (mtDNA) was isolated from muscle specimens of N. coriiceps Richardson, 1844, N. neglecta Nybelin, 1951 and N. rossii, which were collected in Admiralty Bay, King George Island. The DNA was used to amplify a fragment (690 base pairs) of the mitochondrial gene coding region of NADH dehydrogenase subunit 2. Further, the amplicon was digested with the following restriction enzymes: DdeI, HindIII and RsaI. The results showed a variation of the digestion pattern of the fragment amplified between N. rossii, and N. coriiceps Richardson, 1844 or N. neglecta Nybelin, 1951. However, no differences were found between N. coriiceps Richardson, 1844 and N. neglecta Nybelin, 1951, on the grounds of the same genetic pattern shown by the two fish.南极鱼类的分类学研究长期以来主要以形态学特征为依据，而非遗传学标准。典型案例为诺托滕鱼属（Notothenia）类群，该类群包含1844年Richardson命名的N. coriiceps、1951年Nybelin命名的N. neglecta以及1844年Richardson命名的N. rossii。本研究采用聚合酶链式反应-限制性片段长度多态性（PCR-RFLP）技术，旨在探究N. coriiceps与N. neglecta究竟为独立物种，还是仅存在形态、生理及行为变异的同一物种，实验以N. rossii作为对照。实验样本采自乔治王岛阿德默勒尔蒂湾的上述三种鱼类，研究人员从其肌肉组织中分离出线粒体DNA（mtDNA）。以提取的线粒体DNA为模板，扩增编码NADH脱氢酶亚基2的线粒体基因片段，扩增产物长度为690个碱基对。随后使用DdeI、HindIII及RsaI三种限制性内切酶对扩增子进行酶切处理。结果显示，N. rossii与N. coriiceps或N. neglecta的扩增片段酶切模式存在显著差异；但N. coriiceps与N. neglecta的酶切遗传模式完全一致，未检测到任何遗传差异。