Body Size Differences Between New World and Old World, Arboreal, Tropical Vertebrates: Cause and Consequences

Abstract

An hypothesis is put forward to explain the differences in body size and dietary habits between neotropical and palaeotropical primates. Earlier explanations are shown to be unsubstantiated, and the neotropics are shown to have fewer large arboreal vertebrates than the palaeotropics. It is postulated that the more fragile vegetation of the neotropics has precluded the evolution of a large body size in primates and in other birds and mammals. Conversely, fragile vegetation might permit the proliferation of small species that can forage economically in them. Finally, a reduction in body size can have other consequences, such as an insect fauna displaying very diverse antipredator adaptations. The fragile vegetation hypothesis explains the small body size of neotropical vertebrates, the frugivore-fruit interactions found in the neotropics, and the morphological diversity of neotroDical Insecta.