The studies of primate communities that have compared primate species' ecological characteristics have found major differences among Africa, the Neotropics, Asia, and Madagascar (Raemaekers et al., 1980; Bourlière, 1985; Terborgh & van Schaik, 1987; Gautier-Hion, 1988; Ganzhorn, 1988, 1992; this volume; Terborgh, 1990; Fleagle & Reed, 1996; Kappeler & Heymann, 1996; McGraw, 1998). These studies have also shown ecological patterns within the same continental areas. However, most of these previous studies compare ecological differences among primate communities on different continents with attributes of individual species, i.e., contrasts in size, diet, and locomotor adaptations among individual species within communities. The unit of analysis is the species. Using these data, Fleagle & Reed (1996) showed that overall ecological space represented by ecological data occupied by primate species in communities were quite similar within continental areas, and were different between them. Thus, each primate species within each community held a particular position in ecological space (Hutchinson, 1978).
However, primates, for the most part, do not live individually. The density of primates, as well as diversity, presumably affects the size and shape of the ecological space that each community holds. For example, mammalian population density has been directly related to the size of an animal such that as animals get larger their population densities usually decrease (Fa & Purvis, 1997). It has been suggested that the scaling of this phenomenon is approximately the same for all mammalian herbivores (Damuth, 1981). Peters (1983) proposes that one of the most important reasons that population density falls with increasing body size is the constraint of food supply.