Sumida Masayuki, Ueda Hiroaki, Nishioka Midori
Institute for Amphibian Biology, Graduate School of Science, Hiroshima University, Higashihiroshima, Japan.
Zoolog Sci. 2003 May;20(5):567-80. doi: 10.2108/zsj.20.567.
Crossing experiments were made among various brown frog species and populations collected from Japan, China, Russia and Taiwan. The main purpose of these experiments was to confirm the existence of reproductive isolating mechanisms among Rana pirica from Japan, R. chensinensis from China and R. chensinensis from Russia, and between these three taxa and the other brown frogs distributed in the Palearctic and Oriental regions. It was found that there was no or a slight gametic isolation among the three taxa. While there was a nearly equal number of male and female offspring in the control groups, the hybrid frogs were all males, and completely sterile upon attaining sexual maturity. Thus, each of the Japanese R. pirica and the Russian R. chensinensis is a valid species, distinct from the Chinese R. chensinensis. The phylogenetic tree based on nucleotide sequence data from the mitochondrial 12S and 16S rRNA genes of the Palearctic and Oriental brown frogs showed that the three taxa are included in a cluster together with the other species with 2n=24 chromosomes. The present crossing experiments and molecular data support the hypothesis that each of them is a separate but closely related species.
对从日本、中国、俄罗斯和台湾采集的各种棕色蛙类物种和种群进行了杂交实验。这些实验的主要目的是确认日本林蛙、中国林蛙和俄罗斯林蛙之间，以及这三个分类单元与分布在古北界和东洋界的其他棕色蛙类之间生殖隔离机制的存在。结果发现，这三个分类单元之间不存在或仅有轻微的配子隔离。对照组中雌雄后代数量几乎相等，而杂交蛙均为雄性，性成熟后完全不育。因此，日本林蛙和俄罗斯林蛙各自都是有效物种，与中国林蛙不同。基于古北界和东洋界棕色蛙线粒体12S和16S rRNA基因核苷酸序列数据构建的系统发育树表明，这三个分类单元与其他2n = 24条染色体的物种一起被归入一个类群。目前的杂交实验和分子数据支持了它们各自是独立但亲缘关系密切的物种这一假说。
