Community evolution in forest habitats

Abstract

Hominoid primates have had a mainly tropical forest distribution throughout their history. At present, the forest habitats occupied by apes include a variety of vegetation types, for example lowland evergreen tropical forest, montane evergreen forests, medium altitude semi-deciduous forests, and even deciduous forest-scrub. A similar spectrum of vegetation types appears to have been occupied by Eocene and Oligocene primates, as well as at least some of the Miocene apes in Africa. The nature of these habitats is investigated both by reviewing the adaptations of the mammals in relation to the floral composition and by investigating the community structure of the mammalian faunas. Community structure is measured by body size spectra, dietary guilds, trophic patterns and diversity indices, both analysed separately and in combination using multivariate techniques. Comparisons are made between the Eocene and Present in order to document the changes in community structure which occurred during this time, with special attention being given to primates. Taxonomic shifts that have occurred in the East African mammalian faunas between Miocene and Present have produced little change in the community structure, indicating that Miocene forest habitats were structurally similar to those of today, whereas the differences observed in the Eocene faunas represent both a taxonomic and an ecologic change. Between the late Eocene and early Miocene there was a reorganization of mammalian community structure for which an explanation must be sought, either in changes in the relationships between mammals and plants between the Eocene and Present or in ecological changes in forest habitats during this time.