Neotropic

From Free net encyclopedia

The Neotropic ecozone is a terrestrial ecoregion which includes South America, Central America, and the Caribbean. It has distinct fauna and flora from the Nearctic because its long separation from the northern continent.

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This ecozone includes South and Central America, the Mexican lowlands, the Caribbean islands, and southern Florida, because these regions share a large number of plant and animal groups. It is sometimes used as a synonym for the tropical area of South America, although the ecozone also includes temperate southern South America.

The Neotropic includes more tropical rainforest (tropical and subtropical moist broadleaf forests) than any other ecozone, extending from southern Mexico through Central America and northern South America to southern Brazil, including the vast Amazon Rainforest. These rainforest ecoregions are one of the most important reserves of biodiversity on Earth. Extensive deforestation in the late 20th century has reduced this diversity to a degree.

These rainforests are also home to a diverse array of indigenous peoples, who to varying degrees persist in their autonomous and traditional cultures and subsistence within this environment. The number of these peoples who are as yet relatively untouched by external influences continues to decline significantly, however, along with the near-exponential expansion of urbanization, roads, pastoralism and forest industries which encroach on their customary lands and environment. Nevertheless amidst these declining circumstances this vast "reservoir" of human diversity continues to survive, albeit much depleted. In South America alone some 350-400 indigenous languages and dialects are still living (down from an estimated 1,500 at the time of first European contact), in about 37 distinct language families and a further number of unclassified and isolate languages. Many of these languages and their cultures are also endangered. Accordingly, conservation in the Neotropic zone is a hot political concern, and raises many arguments about development versus indigenous versus ecological rights and access to / ownership of natural resources.

The temperate forest ecoregions of southwestern South America, including the temperate rain forests of the Valdivian temperate rain forests and Magellanic subpolar forests ecoregions, and the Juan Fernandez Islands and Desventuradas Islands, are a refuge for the ancient Antarctic flora, which includes trees like the southern beech (Nothofagus), podocarps, the alerce (Fitzroya cupressoides), and Araucaria pines like the monkey-puzzle tree (Araucaria araucana). These magnificent rainforests are endangered by extensive logging and their replacement by fast-growing non-native pines and eucalyptus.

South America was originally part of the supercontinent of Gondwana, which included Africa, Australia, India, New Zealand, and Antarctica, and the Neotropic shares many plant and animal lineages with these other continents, including Marsupial mammals and the Antarctic flora. After the final breakup of the Gondwana, South America drifted north and west, and was later joined with North America by the formation of the Isthmus of Panama, which allowed a biotic exchange between the two continents, the Great American Interchange. South American species like the ancestors of the Virginia Opossum (Didelphis virginiana) and the armadillo moved into North America, and North Americans like the ancestors of South America's camelids, including the llama (Lama glama), moved south. The long-term effect of the exchange was the extinction of many South American species, mostly by outcompetion by northern species.