Hayashi J I, Yonekawa H, Gotoh O, Tagashira Y, Moriwaki K, Yosida T H
Biochim Biophys Acta. 1979 Sep 27;564(2):202-11. doi: 10.1016/0005-2787(79)90219-3.
Mitochondrial DNA's (mtDNAs) were prepared from various kinds of individual Norway rats, Rattus norvegicus, and from three types of individual black rats, Rattus rattus, (Asian type, Ceylon type, and Oceanian type). Intra- and interspecies divergence of their mtDNA sequences were calculated based on changes in restriction endonuclease cleavage sites. The extent of intraspecies divergence of black rats (about 8%) is much larger than that of Norway rats (1%) and the mtDNA of Asian-type black rats resembles the mtDNA of Norway rats more closely than it resembles the mtDNA of other types of black rats. These results strongly suggest that during the course of intraspecies differentiation of black rats, probably long after the separation of the three types of black rats, some Asian-type black rats were isolated sexually and formed a new species, Norway rats. On the basis of our observations we propose a hypothetical process to explain the evolution of animal mtDNA.
线粒体DNA（mtDNA）取自各种挪威大鼠（褐家鼠）个体以及三种类型的黑鼠（黑家鼠）个体（亚洲型、锡兰型和大洋洲型）。基于限制性内切酶切割位点的变化，计算了它们mtDNA序列的种内和种间差异。黑鼠的种内差异程度（约8%）远大于挪威大鼠（1%），并且亚洲型黑鼠的mtDNA与挪威大鼠的mtDNA更为相似，而与其他类型黑鼠的mtDNA差异较大。这些结果有力地表明，在黑鼠的种内分化过程中，可能在三种类型的黑鼠分离很久之后，一些亚洲型黑鼠在生殖上被隔离并形成了一个新物种——挪威大鼠。基于我们的观察结果，我们提出了一个假设过程来解释动物mtDNA的进化。
