STUDIES ON THE POSITION OF THE QINGHAI-XIZANG PLATEAU REGION IN ZOOGEOGRAPHIC DIVISIONS AND ITS EASTERN DEMARCATION LINE

In this paper, from a historically temporal and spatial piont of view, we analysed the process and the uniqueness of the ichthyo-fauna differentiation in Qinghai-Xizang plateau from Tertiary to present, and suggested that the ichthyo-fauna differentiation due to the uplift of the Qinghai-Xizang plateau might have been reflected in zoogeographic divisions (i. e.the Qinghai-xizang plateau should be considered as an independent unit). The formation of a certain zoogeographical division unit is surely related to a definite event in a given geological period, and the division of Holarctic Region and the Oriental Region is related to the temperature decrease that occurred in the middle stage of Tertiary period. The formation of the Qinghai-Xizang plateau region is surely related to the uplift of the Qinghai-Xizang plateau. The upheavae of the plateau and the global temperature decrease occurred almost at the same period and might have made certain influences. These hictorical events jointly urged the differentiation of the Eurasia ichthyo-fauna, which led to the division among the Holarctic Region, the Oriental Region and the Qinghai-Xizang Plateau Region. As a Region reflection of those events that happened at the same period, the Holarctic Region, the Oriental Region and the Qinghai-Xizang Plateau Region must have equal positions in zoogeographic divisions. The natural distribution boundary of plateau fishes (i.e.the subfamily Schizothroacinae and the genus Triplophysa) formed the demarcation line of the Qinghai-Xizang plateau region. In the eastern part of the plateau region, concerning the cutting of the same river into two parts, the range of the plateau region was also limited in area where Eastern Asiatic or river-plain fishes can not reach.