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TheNeotropical realm is one of the eightbiogeographic realms constituting Earth's land surface. Physically, it includes thetropicalterrestrial ecoregions of theAmericas and the entireSouth Americantemperate zone.
Inbiogeography, the Neotropic or Neotropical realm is one of the eightterrestrial realms. This realm includes South America,Central America, theCaribbean Islands, and southernNorth America. InMexico, theYucatán Peninsula and southern lowlands, and most of the east and west coastlines, including the southern tip of theBaja California Peninsula are Neotropical. In theUnited States,South Florida and coastalCentral Florida are considered Neotropical.[2]
The realm also includes temperate southern South America. In contrast, the NeotropicalFloristic Kingdom excludes southernmost South America, which instead is placed in theAntarctic kingdom.
The Neotropic is delimited by similarities infauna orflora. Its fauna and flora are distinct from theNearctic realm (which includes most of North America) because of the long separation of the two continents. The formation of theIsthmus of Panama joined the two continents two to three million years ago, precipitating theGreat American Interchange, an importantbiogeographical event.
The Neotropic includes moretropical rainforest (tropical and subtropical moist broadleaf forests) than any other realm, extending from southern Mexico through Central America and northern South America tosouthern Brazil, including the vastAmazon rainforest. These rainforest ecoregions are one of the most important reserves ofbiodiversity on Earth. These rainforests are also home to a diverse array ofindigenous peoples, who to varying degrees persist in their autonomous and traditional cultures andsubsistence 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 ofurbanization, roads,pastoralism andforest 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 350–400indigenous languages and dialects are still living (down from an estimated 1,500 at the time offirst European contact), in about 37 distinctlanguage families and a further number ofunclassified andisolate languages. Many of these languages and their cultures are alsoendangered. 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 ofnatural resources.
TheWorld Wide Fund for Nature (WWF) subdivides the realm intobioregions, defined as "geographic clusters of ecoregions that may span several habitat types, but have strong biogeographic affinities, particularly at taxonomic levels higher than the species level (genus, family)".
Laurel forest and othercloud forest are subtropical and mild temperateforest, found in areas with high humidity and relatively stable and mild temperatures.Tropical rainforest,tropical and subtropical moist broadleaf forests are highlight[clarification needed] in Southern North America,Amazonia,Caribbean, Central America,Northern Andes and Central Andes.[citation needed]
TheAmazonia bioregion is mostly covered bytropical moist broadleaf forest, including the vastAmazon rainforest, which stretches from the Andes Mountains to theAtlantic Ocean, and the lowland forests of theGuianas. The bioregion also includestropical savanna andtropical dry forest ecoregions.[3]
The Central Andes lie between the gulfs ofGuayaquil andPenas and thus encompass southernEcuador,Chile,Peru, westernBolivia, and northwest and westernArgentina.[4]
Eastern South America includes theCaatingaxeric shrublands ofnortheastern Brazil, the broadCerrado grasslands and savannas of theBrazilian Plateau, and thePantanal andChaco grasslands. The diverseAtlantic forests of easternBrazil are separated from the forests of Amazonia by the Caatinga and Cerrado, and are home to a distinct flora and fauna.[5]
North of theGulf of Guayaquil in Ecuador andColombia, a series of accretedoceanic terranes (discreteallochthonous fragments) have developed that constitute the Baudo, or Coastal, Mountains and the Cordillera Occidental.[6]
TheOrinoco is a region of humid forestedbroadleaf forest andwetland primarily comprising thedrainage basin for the Orinoco River and other adjacent lowland forested areas. This region includes most ofVenezuela and parts of Colombia, as well asTrinidad and Tobago.
The temperate forest ecoregions of southwestern South America, including thetemperate rain forests of theValdivian temperate rain forests andMagellanic subpolar forests ecoregions, and theJuan Fernández Islands andDesventuradas Islands, are a refuge for the ancientAntarctic flora, which includes trees like thesouthern beech (Nothofagus),podocarps, thealerce (Fitzroya cupressoides), andAraucaria pines like themonkey-puzzle tree (Araucaria araucana). These rainforests are endangered by extensive logging and their replacement by fast-growing non-nativepines andeucalyptus.
South America was originally part of the supercontinent ofGondwana, which includedAfrica,Australia,India,New Zealand, andAntarctica, and the Neotropic shares many plant and animal lineages with these other continents, includingmarsupial mammals and the Antarctic flora.
After the final breakup of the Gondwana about 110 million years ago, South America was separated from Africa and drifted north and west. 66 million years ago, theCretaceous–Paleogene extinction event altered local flora and fauna.[7][8] Much later, about two to three million years ago, South America was joined with North America by the formation of theIsthmus of Panama, which allowed a biotic exchange between the two continents, theGreat American Interchange. South American species like the ancestors of theVirginia opossum (Didelphis virginiana) and thearmadillo moved into North America, and North Americans like the ancestors of South America'scamelids, including thellama (Lama glama), moved south. The long-term effect of the exchange was the extinction of many South American species, mostly by outcompetition by northern species.
The Neotropical realm has 31 endemic bird families, which is over twice the number of any other realm. They includetanagers,rheas,tinamous,curassows,antbirds,ovenbirds,toucans, andseriemas. Bird families originally unique to the Neotropics includehummingbirds (family Trochilidae) andwrens (family Troglodytidae).
Mammal groups originally unique to the Neotropics include:
The Neotropical realm has 63 endemicfish families and subfamilies, which is more than any other realm.[9]Neotropical fishes include more than 5,700 species, and represent at least 66 distinct lineages in continental freshwaters (Albert and Reis, 2011). The well-knownred-bellied piranha is endemic to the Neotropic realm, occupying a larger geographic area than any other piranha species. Some fish groups originally unique to the Neotropics include:
Examples of other animal groups that are entirely or mainly restricted to the Neotropical region include:
According to Simberloff. as of 1984 there were a total of 92,128 species offlowering plants (Angiosperms) in the Neotropics.[11]Plant families endemic and partly subendemic to the realm are, according to Takhtajan (1978),Hymenophyllopsidaceae,Marcgraviaceae,Caryocaraceae,Pellicieraceae,Quiinaceae,Peridiscaceae,Bixaceae,Cochlospermaceae,Tovariaceae, Lissocarpaceae (Lissocarpa),Brunelliaceae,Dulongiaceae,Columelliaceae,Julianiaceae,Picrodendraceae,Goupiaceae,Desfontainiaceae,Plocospermataceae,Tropaeolaceae, Dialypetalanthaceae (Dialypetalanthus), Nolanaceae (Nolana),Calyceraceae,Heliconiaceae,Cannaceae,Thurniaceae, andCyclanthaceae.[12][13]
Plant families that originated in the Neotropic includeBromeliaceae,Cannaceae andHeliconiaceae.[14]
Plant species with economic importance originally unique to the Neotropic include:[15]
The Neotropical Region is one of the major biogeographic divisions for both plants and animals on Earth. It spans from central Mexico and the Caribbean islands to southern South America. The Neotropical Region contains the largest number of mammal species in the New World, and is the region with the largest number of endemic mammal families.
