The Origin and Evolution of Ant Fauna of The Tropical Rain Forest in Xishuangbanna,China

From early Cambrian to early Jurassic,Xishuangbanna Oldland and Burma Oldland formed a whole oldland,and had the same history of species origin and evolution.But Xishuangbanna Oldland sank under the sea twice in late Carboniferous and middle and late Jurassic,all achievements in species origin and evolution were spoiled.The ants originated in middle and late Cretaceous or even earlier,and differentiated greatly in Palaeogene.To early Cretaceous,Xishuangbanna Oldland connected with Burma and China Oldlands,and never sank again from then on.So the species of Xishuangbanna Oldland were immigrated from Burma and China Oldlands since that time.To the initial stage of Himalayan Movement in Palaeogene,the northwest to southeast trend Western Yunnan Basin disappeared.Southwestern,southern and central China formed a uniform continent with similar landforms,and this provided a convenient condition for the interflow of species in west-east and north-south directions.At the same period,the India subcontinent jointed to the Asian continent,species of the two continents began to exchange extensively.To the later stage of Himalayan Movement in early Pleistocene of Quaternary,the continent north of Simao raised up distinctly,and species of Xishuangbanna divided from the fauna of China,but maintained close interflow in the west,south and east directions.To the middle and late Pleistocene of Quaternary,along with the formation of the Hengduanshan Mountains,Xishuangbanna area was correspondingly weakly raised up,and the complicated and varied landforms and climates in this area were gradually formed.The change of environment led to differentiation of species,and Xishuangbanna area became a distinct center for species differentiation.