中国林蛙Rana chensinensis系统发育及物种形成和分化的研究

ON THE PHYLOGENETIC RELATIONSHIP AND SPECIATION OF RANA CHENSINENSIS

运用分支分类法,通过形态、染色体和同工酶性状分析寻找出姐妹群,建立中国林蛙各亚种系统发育分支图。并根据地理分布、古地理和古气候特点,认为中国林蛙起源于西伯利亚勒拿河以东。讨论了中国林蛙的分化及与其近缘种的亲缘关系。根据形态推测起源中心时,应考虑环境变化因素,当分布区环境不变或呈单向性变化时,保留祖征最多的亚种所在地就是该物种的起源中心。

11 characters of the four subspec;es of Rana chensincnsis, including morphology, chromosome and LDH isoenzyme, have been analysed with the method of cladistics. The phylogenetic cladogram of the subspecies is presented (Fig. 1).According to the analysis of the characters, ancient geography and climate, it seems reasonable to propose that the east of Lena River in Siberia may probably be the place where Rana chensinensis might have its origin. The glacial epoch of the fourth period forced Rana chensis-ensis move to the south of Asia and it adaptd to new environment and speciated.According to the degree of similarity of the present and original living environments, it is worthy of note that initially speciating subspecies may have more plesiomorphies or more ap-omorphies.Traditionally speaking, there are two theories about the original place, one is that the form of a low level of development in the process of evolution as a more or less reliable indicator of the dispersal center of the taxon, i, e, the nearer the species is to its original center, he lower it is at the level of development; the other is that the form of a comparatively lower level are all excluded to the peripheral region of the distributional range of the taxon. But our study shows that the changed factors of the environment should be considered in determination of the origin center on tht basis of morphology. While the environment did not change or changed the same way all over the distribution, the distributional area of the form with the most plesiomorphies might be the original center of the taxon.