地质变迁与云南白蚁的发生

EFFECT OF GEOLOGICAL VICISSITUDE ON ORIGINATION OF TERMITE FROM YUNNAN, CHINA

由不同板块相嵌构成的云贵高原,是当今世界上形成比较新、海拔比较高的高原之一。高原中的地质历史,反映在二十多亿年来完整的地层中所包含的丰富的古生物化石种类。据统计,已发现的各类化石有14个门类、650多属、2,300多种。是我国古生物类群比较集中和在进化上较完整的地区,也是研究高原的形成和生物的起源和演化历史的珍贵材料。本文就云南在地质变迁过程中所产生的某些影响,试对云南白蚁的发生做初步探讨。

Evidence is interpreted as showing that, Yunnan-Guizhou Plateau is a mosaic texture formed by different continents. It is one of the younger and heigher elevated plateaus of the world. Stereogeological landscape and more than 2,000 species of fossil biologic group has been shown that there is the complete evolutionary area of paleobiologic group. It is considered that Termite-Isoptera, is the ancient entomologic group, and it is closely related with cockroach-Blattaria genetically.The earliest fossil of termite has been found in Mesozoic Cretaceous period on earth. For this reason, some entomologists considered that the ancient termite may be originated in that geologic ages. But some one deemed in earlier Triassic period (Rots 1956) or even in earlier Carboniferous perid (Kapoor 1981). Yunnan district is one of the component part of the termite group of the world. According to the geographic location, fossil group and changing climate, the originating ages of ancient termite is probably between later Permian and earlier Triassic periods. It is based on the following arguments. 1. The most ancient cockroach fossil of China (Archimylacridae : Cubito-blatta concina Lin 1978) was found at the northeast and northwest area between Yunnan and Guizhou Provinces in later Permian period (Lin 1978). Although the ancient fossil termite still doesn't find out in Yunnan at present, but it at least has been showing that the basis of genealogical relationship of origination and evolution of termite has been provided in that period. 2. At the time of Carboniferous period, Yunnan district was located in oceanic ingression from northwest and southeast, and inundated gradually to Anning region, which is located in the central part of Yunnan. Gaoligong Mountain and Bomma Mountain just looks like two islandi appeared on the sea level. In later Permian period, after gcotccnotic movement, marshland appeared o(?) the western margin of the Dianzhong ancient land. In earlier Triassic period, west and south region of Yunnan, including Kunming district, uplifted and formed an immense land. The effect of Indo-China movement in medium and later Triassic period, and came into collision with west and east plates, and than produced a large scale epeirogenic movement. Sea receded and Yunnan district formed into land and inland lakes. Therefore, Triassic period was the significant turning epoch and transform maritime space into land, and thus it was probably provided the suitable environment for the origination and evolution of ancient termite. 3. In Permian period, a greater parts of terrestrial globe was situated in cold and dry climate conditions. A multitude of paleobiologic groups couldn't adapted the adverse circumstance and lead to extinguish gradually (Tan 1980). But Yunnan emerged different landscapes in that geologic ages.In earlier Permian period, there were under luxuriant florae and tropical rain climate conditions. Pteriodospemopsida, Tingia, Lepidodendro, tall and big Cordaites forest densely covered on swamp, hill and mountain. In later Permian period, submarine lying wall of northerna margin of Tethys swelled gradually. The sea receded westward. The swampy forest even stretched to northwest region of Tibet. In southwest China, there were still under luxuriant florae and tropical climate conditions. Up to the Triassic period,southern China of which including Yunnan district, was the tropical area of oceanic climate. Tropical flora was composed by pine and cypress forest and fruticeta, of which covered with pteriodosper-mopsida. It seemnd that under this favourable ecologic environment, the ancient termite utilized it for its origination and propagation in all probability. The climatic variations and vegetation of Yunnan belongs to vertical distribution type. In the very long courses of succession, the distribution of termite approximately differentiated into three categories: ( 1 ). Humid thermal type: The main area is deposited on the lower latitude and lower altitude thermal river valley, such as Kalotermitidae,Termitidae. ( 2