PATTERNS OF TROPICAL VERTEBRATE FRUGIVORE DIVERSITY

Abstract

The production of fleshy fruits by angiosperms and their consumption by a diverse array of vertebrates is a quintessential tropical phenomenon. Although fleshy fruits are produced by many kinds of plants in a latitudinally wide variety of habitats, this plant-animal mutualism is most common in the tropics. From 50% to over 90% of the species of tropical shrubs and trees, depending on habitat, rely on fruit-eating vertebrates to disperse their seeds (53). In many tropical forests, the bulk of the vertebrate biomass is supported by fleshy fruits. In tropical moist forest at Cocha Cashu, Peru, for example, frugivorous species made up 80% of the mammalian and avian biomass, according to Terborgh's estimates (117). Approximately 50% of the biomass of forest birds in central Panama is supported by fruit (131). A substantial portion of the increased diversity of tropical mammalian and avian faunas (compared with their temperate counterparts) results from the evolution of fruit-eating species (27, 61, 88). In this review, we examine patterns of vertebrate frugivore diversity in the tropics and discuss the evolutionary and ecological processes that lie behind these patterns. Three basic questions serve as the focus of this review: (a) Do parallel diversity trends exist in different taxonomic groups; (b) are diversity and other ecological trends the same in the Old and New World tropics; and (c) to what extent have historical vs ecological factors influenced these patterns?