, or major habitat types, as defined by Olson & Dinerstein, et al. (2001). The biomes not present are temperate coniferous forests, taiga and boreal forest, and tundra. In
biogeography, the Neotropic or Neotropical realm is one of the eight
terrestrial realms. This realm includes South America,
Central America, the
Caribbean Islands, and southern
North America. In
Mexico, the
Yucatán Peninsula and southern lowlands, and most of the east and west coastlines, including the southern tip of the
Baja California Peninsula are Neotropical. In the
United States,
South Florida and coastal
Central Florida are considered Neotropical. The realm also includes temperate southern South America. In contrast, the Neotropical
Floristic Kingdom excludes southernmost South America, which instead is placed in the
Antarctic kingdom. The Neotropic is delimited by similarities in
fauna or
flora. Its fauna and flora are distinct from the
Nearctic realm (which includes most of North America) because of the long separation of the two continents. The formation of the
Isthmus of Panama joined the two continents two to three million years ago, precipitating the
Great American Interchange, an important
biogeographical event. The Neotropic includes more
tropical rainforest (
tropical and subtropical moist broadleaf forests) than any other realm, 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. 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 Neotropical realm is a hot political concern, and raises many arguments about development versus indigenous versus ecological rights and access to or ownership of
natural resources. == Major ecological regions ==