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The fauna of Indonesia is characterised by high levels of biodiversity and endemicity due to its distribution over a vast tropical archipelago. Indonesia divides into two ecological regions; western Indonesia which is more influenced by Asian fauna, and the east which is more influenced by Australasian species. The Wallace Line, around which lies the Wallacea transitional region, notionally divides the two regions. There is diverse range of ecosystems, including beaches, sand dunes, estuaries, mangroves, coral reefs, sea grass beds, coastal mudflats, tidal flats, algal beds, and small island ecosystems. Environmental issues due to Indonesia's rapid industrialisation process and high population growth, have seen lower priority given to preserving ecosystems. Issues include illegal logging, with resulting deforestation, and a high level of urbanisation, air pollution, garbage management and waste water services also contributing to the forest deterioration. ==Origin of Indonesian fauna== The origin of fauna in Indonesia was determined by geographical and geological events on the Asian continental landmass and the Australasian continental landmass (now Australia). The island of New Guinea is connected with the present Australian continent, formerly as part of the southern supercontinent Gondwana. This supercontinent began to break up 140 million years ago, and the new Australia-New Guinea continent (previously known as Sahul) moved towards the equator. During this period, animals from New Guinea travelled to Australia and vice versa, creating many different species living in different ecosystems. The influence of the Asian continental landmass, on the other hand, was the result of the reformation of the Laurasian supercontinent, which existed after the break-up of Rodinia around 1 billion years ago. Around 200 million years ago, Laurasia split up, forming the continents of Laurentia (now North America) and Eurasia. Due to fluctuating sea levels, mainland Eurasia was not separated completely from the western part of the Indonesian archipelago, allowing animals from the Eurasian mainland passage to the archipelago, and new species evolved. In the nineteenth century, Alfred Russel Wallace proposed the idea of the Wallace Line, a notional line following deep water straits dividing the Indonesian archipelago into two regions, the mainland Asian zoogeographical region (Sundaland) and the Australasian-influenced zoogeographical region (Wallacea). The line runs between Borneo and Sulawesi; and between Bali and Lombok. Although the distance from Bali to Lombok is a relatively short 35 kilometres, the fauna distribution is affected by the line. For example, a group of birds would refuse to cross even the smallest stretches of open water.〔 A second line, lying east, known as Weber's Line, has also been proposed to separate between "transition species" and species of predominant Australian origin. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Fauna of Indonesia」の詳細全文を読む スポンサード リンク
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