The Recent Mammals of the Neotropical Region: A Zoogeographic and Ecological Review

Abstract

The Neotropical Region, which is defined on the basis of its living mammals, is comprised of the Brazilian, Patagonian, and West Indian Subregions. The Middle American Province of the Brazilian Subregion was the primary center of origin, evolution, and dispersal for mammals now living in continental South America. The West Indies also derived its fauna from Middle America, and perhaps also from South America. Faunal interchange between these regions must have taken place since the Middle Tertiary, at the latest. By the time the Isthmian land bridge between Middle and South America was completed during the Pliocene-Pleistocene transition, nearly all modern genera of Neotropical mammals were already differentiated within their present geographic ranges. Five faunal strata of Neotropical mammals are identified on the basis of postulated centers of origin of the ancestral stock, dispersal routes of colonizers, known grades of differentiation of living descendents, and the meager fossil evidence. The living fauna is classified ecologically as sylvan, pastoral, fluviatile, and versatile. The faunas of widely separated and ecologically contrasting biotic areas are then described, and some of the biological factors controlling evolution and dispersal are briefly discussed.