Neotropical realm

Definition

One of eight terrestrial biogeographic realms, encompassing the tropical and subtropical landmasses of the Americas from southern Florida and Mexico through Central and South America, plus the temperate zones of South America. It is bounded by the Nearctic realm to the north and separated from the Afrotropical and Australasian realms by ocean barriers. The realm harbors exceptional arthropod endemism, including entire families of insects (e.g., Heliconiinae butterflies, many lineages of stingless bees in the tribe Meliponini) and arachnids (e.g., several endemic families of harvestmen, Opiliones) shaped by long isolation and diverse Neotropical ecosystems such as Amazonian rainforest, Andean cloud forests, and the cerrado-savanna mosaic.

Etymology

Neo- (Greek neos, 'new') + tropical, reflecting its distinction from the Old World tropics; 'realm' denotes a major biogeographic unit.

Example

The glasswing butterfly Greta oto and the bullet ant Paraponera clavata are iconic Neotropical realm endemics whose distributions are bounded by the realm's biogeographic limits.

Synonyms

• Neotropical region
• Neotropics

Related Terms

• Nearctic realm
• biogeographic realm
• Neotropics
• Endemism
• Amazonia
• Andean zone
• Panama Isthmus
• Great American Biotic Interchange

Usage Notes

Often shortened to 'the Neotropics' in informal usage, though 'Neotropical realm' specifies the biogeographic unit rather than the climatic zone alone. Contrasts with 'Neotropical region' in some older literature, where the latter sometimes excluded temperate South America; modern usage includes the entire continent south of the Nearctic boundary. The realm's northern limit runs roughly along the Mexican transition zone (around 25°N), not at the political border. Specialists distinguish between the realm (historical biogeography) and the Neotropical ecozone/ecoregion concepts (ecological classification).