Neotropical realm

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.

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.

North of the Gulf of Guayaquil in Ecuador and Colombia, a series of accreted oceanic terranes (discrete allochthonous fragments) have developed that constitute the Baudo, or Coastal, Mountains and the Cordillera Occidental.

After the final breakup of the Gondwana about 110 million years ago, South America was separated from Africa and drifted north and west.

[6] Neotropical fishes include more than 5,700 species, and represent at least 66 distinct lineages in continental freshwaters (Albert and Reis, 2011).

[8] 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 and Cyclanthaceae.