Australasia ecozone

The Australasian ecozone includes Australia, the island of New Guinea (including Papua New Guinea and the Indonesian province of Papua), and the eastern part of the Indonesian archipelago, including the island of Sulawesi, the Moluccan islands (the Indonesian provinces of Maluku and North Maluku) and islands of Lombok, Sumbawa, Sumba, Flores, and Timor, often known as the Lesser Sundas. The rest of Indonesia is part of the Indomalayan ecozone. The Australasia ecozone also includes several Pacific island groups, including the Bismarck Archipelago, Vanuatu, the Solomon Islands, and New Caledonia. New Zealand and its surrounding islands are a distinctive sub-region of Australasian ecozone.

Related Topics:
Australia - New Guinea - Papua New Guinea - Indonesia - Papua - Sulawesi - Maluku - North Maluku - Lombok - Sumbawa - Sumba - Flores - Timor - Indomalaya - Bismarck Archipelago - Vanuatu - Solomon Islands - New Caledonia - New Zealand

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From a biological point of view, Australasia is a distinct region with a common evolutionary history and a great many unique plants and animals, some of them common to the entire area, others specific to particular parts but sharing a common ancestry. The long isolation of Australasia from other continents allowed it to evolve relatively independently, and makes it home to many unique families of plants and animals.

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Australia and New Guinea are distinguished by their large population of Marsupial mammals, including kangaroos, possums, and wombats. The last remaining Monotreme mammals, the echidnas and the platypus, are endemic to Australasia. Prior to the arrival of humans about 50,000 years ago, only about one-third of Australasian mammal species were placental.

Related Topics:
Marsupial - Mammals - Kangaroos - Possums - Wombats - Monotreme - Echidna - Platypus - Endemic - Placental

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The boundary between Australasia and Indomalaya follows the Wallace Line, named after the naturalist Alfred Russel Wallace who noted the differences in mammal and bird fauna between the islands either side of the line. The Islands to the west of the line, including Java, Bali, Borneo, and the Philippines share a similar fauna with East Asia, including tigers, rhinoceros, and apes. During the ice ages, sea levels were lower, exposing the continental shelf that links these islands to one another and to Asia, and allowed Asian land animals to inhabit these islands. Similarly, Australia and New Guinea are linked by a shallow continental shelf, and were linked by a land bridge during the ice ages. A group of Australasian islands east of the Wallace line, including Sulawesi, Halmahera, Lombok, Flores, Sumba, Sumbawa, and Timor, is separated by deep water from both the southeast Asian continental shelf and the Australia-New Guinea continental shelf. These islands are called Wallacea, and contain relatively few Australian or Asian mammals. While most land mammals found it difficult to cross the Wallace Line, many plant, bird, and reptile species were better able to make the crossing.

Related Topics:
Wallace Line - Alfred Russel Wallace - Java - Bali - Borneo - Philippines - Tiger - Rhinoceros - Ape - Ice age - Wallacea

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Australia, New Zealand, and New Caledonia are all portions of the ancient supercontinent of Gondwana, which started to break into smaller continents in the Cretaceous era, 130-65 million years ago. New Zealand broke away first, more than 80 million years ago, and Australia finally broke free from Antarctica about 45 million years ago. All the Australasian lands are home to the Antarctic flora, descended from the flora of southern Gondwana, including the coniferous podocarps and Araucaria pines, and the broadleafed southern beech (Nothofagus), and proteas (Proteaceae).

Related Topics:
Gondwana - Cretaceous - Antarctica - Antarctic flora - Coniferous - Podocarps - Araucaria - Southern beech - Proteaceae

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As Australia moved north into the desert latitudes, the continent became hotter and drier, and the soils poorer and leached of nutrients, causing the old Antarctic flora to retreat to the humid corners of the continent in favor new drought and fire tolerant flora, dominated by the Eucalyptus, Casuarina, and Acacia trees, and by grasses and scrub where the rainfall was too scarce to support trees. Presently Australia is the smallest continent, and also the driest continent and the flattest (lowest in elevation) continent.

Related Topics:
Eucalyptus - Casuarina - Acacia

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