a floristic and zoogeographic region of land; its boundaries differ slightly for plants and animals.
Neotropical Floristic Region. The Neotropical Floristic Region is one of the principal geobotanical subdivisions. It occupies the continental part of the New World from Baja California and the southern part of the Meseta Central in the north to 40° S lat. in the south, as well as the islands near Central America. The climate is generally tropical; from 10° to 25° S lat. it is subtropical with a transition to moderate. The rich and varied flora has a prevalence of mesophyllic forest vegetation. Most common are plants of the pantropic families (spurges, laurels, madders, myrtles, melastomes, mulberries, soapberries, palms, orchids), which consist, however, primarily of neotropical genera. Also predominant are such large cosmopolitan families as the Compositae, Gramineae, Leguminosae, Labiatae. There are few endemic families, but some of them, such as bromeliads and cacti, are typical for the composition and appearance of the flora. The flora’s ties with the floras of other regions (in particular, the Paleotropical Region) and its differentiation within the Neotropical Region indicate that it developed for a long time in isolation under relatively stable environmental conditions. The closest relationships (in time) are with the floras of tropical Africa and the high mountains of the northern hemisphere.
The Neotropical Region is subdivided into six subregions. The Caribbean Subregion occupies the outermost parts of Mexico, Central America, and the Antilles, as well as the coastal regions of Colombia and Venezuela. The flora is characterized by numerous species of Myrtaceae, Palmaceae, Leguminosae, Lauraceae, Annonaceae, Piperaceae, and Orchidaceae. Treelike ferns and sago palms are widely distributed. There are a few conifers and many endemic plants in the subregion. The Orinoco Subregion of savannas is characterized by an abundance of legumes, dilleniads, malpigias, and Gramineae. There is a moderate number of endemics.
The Amazon Subregion of humid tropical forest is a vast wooded area in the Amazon Basin (between the eastern foot of the Andes and the Atlantic Ocean, from 6°-10° N lat. to 10°-15° S lat.). The flora is extremely rich and strongly differentiated despite the relative uniformity of conditions. Palms (many endemic), legumes, spurges, and madders are widespread. There are many epiphytes, including orchids, bromeliads, and arums.
The Brazilian Subregion consists of dry sparse woodlands and savannas; it occupies the Brazilian Highlands and adjacent areas north of 30° S lat., and in particular, a large part of the La Plata basin. Unique forms of silt-cotton trees, palms, spurges, and cacti are found there. In the Brazilian campos there are, in addition to arboreal species, numerous tropical species of Gramineae, Compositae, Leguminosae, and Labiatae. In southern Brazil there are unique combinations of tropical and subtropical evergreen trees and shrubs with forest-forming araucarias.
The La Plata Subregion, which consists of pampas, extends from 10° to 30° S lat. between the Andes and the Atlantic Ocean. It is characterized by specifically neotropical grasses, composites, nightshades, and vervains. Species imported from the Old World are also common.
The Andes Subregion occupies mountainous areas of South America from Colombia to central Chile. The vegetation is highly differentiated according to latitude, elevation above sea level, and exposure to prevailing winds. There is a complex combination of mesophyllic forests of different zonal types, evergreen forests, high mountain formations (puna and paramo), and deserts. There are many endemic species and genera. Genetic relationships with the mountain floras of the northern hemisphere and nontropical south can be traced. The floras of the Galápagos and Juan Fernandez islands in the Pacific Ocean occupy a special place.
REFERENCESVul’f, E. V. Istoricheskaia geografiia rastenii: Istoriia flor zemnogo shara. Moscow-Leningrad, 1944.
Alekhin, V. V., L. V. Kudriashov, and V. S. Govorukhin. Geografiia rastenii s osnovami botaniki, 2nd ed. Moscow, 1961.
Diels, L. Pflanzengeographie, 5th ed. Berlin, 1958.
Good, R. The Geography of Flowering Plants, 3rd ed. London, 1964.
Hueck, K. Die Wälder Südamerikas. Jena, 1966.
The bird fauna in the Neotropical Region is exceptionally rich. It includes rheas and the Crypturiformes, as well as numerous woodhewers, hummingbirds, parrots (including the genus Ara), shrieking Passeriformes (for example, Procnias averano and cocks-of-the-rock), the hoatzin, condors, harpy eagles, and toucans. There are more than 20 endemic families of birds in the Neotropical Region, only a few of which extend into the Holarctic Region.
The reptiles in the region include caimans, crocodiles, various side-necked turtles, snakes (rattlesnakes, boas), and lizards (especially iguanas). Typical amphibians are apodals and a large number of batrachians (tree toads, pipa frog). Widespread fish forms include the South American lungfish, the pirarucu, and the piranha (caribe).
The insect life in the Neotropical Region includes vast numbers of ants and leaf cutters, which cultivate fungi under the ground and fertilize the soil with tiny leaf parts. Large, brightly colored butterflies are common. Outstanding among the spiders is the bird spider (Avicularia avicularia), which is capable of capturing small birds. The Neotropical Region is subdivided into three subregions: the Guiana-Brazilian Subregion; the Patagonian-Andean, or Chilean-Patagonian, Subregion; and the Antilles Subregion.
Despite its prolonged isolation, the fauna of the Neotropical Region was influenced to some extent by the faunas of other regions with which there were connections either in the remote geological past or later. The most ancient fauna relationships are with the Australian and Ethiopian regions. Some scientists conjecture that the marsupials came to Australia from South America across Antarctica during the Cretaceous Period. The ancient relationship with the Ethiopian Region and Madagascar is indicated by the similarity between the solenodonts and the tenrecs, as well as the distribution of manatees (West Africa) and dipnoan fish. The Neotropical Region produced very few domesticated animals: for example, the llama and the guinea pig, the duck, and the cochineal.
REFERENCESGeptner, V. G. Obshchaia zoogeografiia. Moscow-Leningrad, 1936.
Puzanov, I. I. Zoogeografiia. Moscow, 1938.
Bobrinskii, N. A., L. A. Zenkevich, and la. A. Birshtein. Geografiia zhivotnykh. Moscow, 1946.
Darlington, F. Zoogeografiia. Moscow, 1966. (Translated from English.)
V. G. GEPTNER