CHARACTERISTICS OF THE FISH-FAUNA OF THE CHARACTERISTICS OF QINGHAI-XlZANG PLATEAU AND ITS GEOLOGICAL DISTRIBUTION AND FORMATION
WU YUN-FEI TAN QI-JIA (Northwest Plateau Institute of Biology, Academia Sinica, Qinghai, Xining)
Based on a great quantity of information obtained from the author's on-the-spot investigations, the present paper advances an analyse and conclusion of the fish-fauna in QinghaiXizang Plateau, and provides a distributional list of 6 families, 26 genera and 114 species of fishes in every river system. The first part illustrates the outline of the simplicity of the fishfauna composition and the complexity of the river systems, then sets forth the relationships among the fish-fauna in Qinghai-Xizang Plateau and Xinjiang arid areas and that within the plateau. The second, by analysing distributive features, identifies the three characters of fish distributions in Qinghai-Xizang Plateau, i. e. there are distinct geographical boundaries across outflow rivers, showing the discontinuous island-like distribution in southeast external river systems, and clear zonation in the vertical height. The third, by analysing the fauna characters and integrating the relevant information of historical geography, climate and fish fossils, discusses the geologichistorical causes of the plateau fish-fauna formation. It is considered that, at early Tertiary Period, the primitive barbine fishes and nemacheiline fishes, which adapted to live in warm waters, had already widely dispersed in eastern and central Asia. The existing fish-fauna in plateau was not formed through dispersals from a original centre, but through the isolations caused by three important geological events of Himalaya Movement, which leaded to the separations of the fishes in the plateau and other areas. Respectively, the events are: 1. the second uplift of "Xikang Mountain Chain", caused by the closure of Himalaya geosyncline which resulted in the separations of the fish-fauna between Certral Asia and Eastern Asia. 2. the uplift of Himalaya Mountains brounght about the separation of the fishfauna between Central Asia and Southern Asia. 3. the second uplift of Alkin Mountain and other mountains resulted in the separation of the fish-fauna in Central Asia and finally leaded to the primary form of the particular fishfauna in Qinghai-Xizang Plateau.Besides, it is expounded that the eastern boundary of fish-fauna in Qinghai-Xizang Plateau is actually the reflection of the ancient Xikang dividing ridge. It is also been explaind why the fishes in Qinghai-Xizang Plateau dispersed to India earlier than the fishes in Yunnan and why the fish-fauna shows differentiations between the South and the North.