Neotropical realm

Neotropical realm is the biogeographic region encompassing most of South America, Central America, the Caribbean Sea islands and southern parts of Mexico. It contains globally significant ecosystems such as the Amazon rainforest, the Cerrado, the Pantanal and the Andes montane belts. The realm is a focus of international conservation efforts involving organizations like World Wildlife Fund, Conservation International, The Nature Conservancy and treaties such as the Convention on Biological Diversity and the Ramsar Convention.

Geography and boundaries

The realm covers the tropical and subtropical Americas from southern Mexico through the Caribbean Sea to the southern cone of South America, bounded by the Nearctic realm transition across the Isthmus of Tehuantepec and the Bering Strait-separated Pacific influences; maritime boundaries include the Caribbean Sea and the South Atlantic Ocean. Major physiographic features include the Amazon Basin, the Orinoco River drainage, the La Plata Basin, the Guiana Shield, the Brazilian Shield, and island systems such as the Greater Antilles and the Lesser Antilles. Prominent mountain chains and plateaus are the Andes, the Sierra Madre del Sur, the Guiana Highlands, and the Puna de Atacama, while coastal plains include the Llanos and the Patagonian steppe fringes.

Climate and biomes

Climates range from equatorial tropical rainforest regimes in the Amazon Basin and Darien Gap to monsoonal patterns in the Atlantic Forest and seasonally dry patterns in the Caatinga and Gran Chaco. High-elevation climates appear along the Andes with puna, páramo and montane forest belts, while temperate climates occur in parts of Argentina and Chile influenced by the Humboldt Current and Falkland Current. Major biomes include the Amazon rainforest, Atlantic Forest, Cerrado savanna, Caatinga xeric shrublands, Chaco dry forest, Pantanal wetlands, Patagonian steppe, and various island biotas of the Caribbean Sea and Galápagos Islands.

Flora and fauna

Floral diversity includes hyperdominant tree genera of the Amazon rainforest such as Protium, Aniba, and Bertholletia, vast palm lineages across the Neotropics and endemics in the Madrean pine–oak woodlands and Valdivian temperate rainforests. Faunal assemblages feature iconic groups: sloths, anteaters, armadillos (xenarthrans), Neotropical bats including families such as Phyllostomidae, diverse primates like howler monkeys and spider monkeys, and carnivores including jaguar, ocelot, and cougar. Avian diversity is exceptional, with radiations of toucans, hummingbirds, tanagers, macaws and antbirds; freshwater fishes include diverse Characiformes, Siluriformes catfishes and the iconic piranha. Amphibian richness is represented by families such as Hylidae and Dendrobatidae while reptiles include boas, caimans and endemic lizard clades in the Galápagos Islands. Economically and culturally important species include Hevea brasiliensis (rubber tree), Ilex paraguariensis (yerba mate), and crop wild relatives of Solanum and Capsicum.

Biogeographic history and evolution

The biogeographic history involves Gondwanan legacies, Andean uplift, and the formation of the Isthmus of Panama during the Pliocene, which precipitated the Great American Biotic Interchange between North America and South America. Paleoecological records from sites like the La Brea Tar Pits (for late Pleistocene comparisons) and Lake Titicaca cores inform Quaternary dynamics that influenced megafaunal extinctions exemplified by genera such as Megatherium and Glyptodon. Major evolutionary drivers include vicariance across the Amazon River and dispersal linked to El Niño–Southern Oscillation variability, with adaptive radiations in clades such as Neotropical hummingbirds, passerines (e.g., tanagers), and Neotropical orchids involving mutualists like leafcutter ants and pollinators such as euglossine bees.

Conservation and threats

Conservation challenges include deforestation in the Amazon rainforest driven by agriculture and logging linked to commodity chains involving soybean and beef exports, habitat conversion in the Cerrado for biofuel crops, wetland drainage in the Pantanal, and coral reef degradation in the Mesoamerican Barrier Reef System. Climate change impacts interact with land use, influencing fire regimes in the Atlantic Forest and drought frequency in the Gran Chaco and Caatinga. Conservation initiatives operate through protected areas such as Serra do Divisor National Park, Yasuní National Park, Manú National Park, and multinational corridors promoted by entities like the Amazon Cooperation Treaty Organization and the Inter-American Development Bank. Threats from invasive species include introductions of tilapia and Africanized bees, while illegal wildlife trade affects taxa such as macaws and golden lion tamarins. Restoration and policy tools include payment for ecosystem services schemes tested in Costa Rica, Indigenous stewardship exemplified by Kayapó and Yanomami territories, and scientific monitoring by institutions like the Smithsonian Tropical Research Institute and the International Union for Conservation of Nature.

Category:Biogeographic realms