Published online by Cambridge University Press: 21 August 2009
The chapters in the preceding section have reviewed evidence that the present structure of primate communities is affected by resource abundance (Janson & Chapman, chapter 14, Peres, chapter 15), food quality and digestive strategies (Janson & Chapman), seasonality (Janson & Chapman; Tutin & White, chapter 13), disease (Tutin & White), contemporary hunting (Peres), recent land-use history (Tutin & White), climatic change in the recent past and the Pleistocene (Tutin & White; Eeley & Lawes, chapter 12), and regional species source pools (Eeley & Lawes; Peres). Despite the diversity of these themes, they fall into two broad contrasts which we shall use to review the preceding results: (1) local vs. regional explanations of primate community structure; and (2) equilibrial vs. nonequilibrial views of community structure.
LOCAL VS. REGIONAL DETERMINANTS OF PRIMATE COMMUNITY STRUCTURE
There is a tension between explanations that rely on local versus regional ecological factors to explain local site diversity. Local factors include resource abundance and quality, seasonality, competition and contemporary hunting. Regional analysis focuses on regional source pools of species – a local site cannot have a primate species that is not in the regional source pool. This distinction is essentially parallel to that between alpha-and gamma-diversity in community ecology. Alpha-diversity reflects the number of coexisting species in a single site, whereas gamma-diversity includes additional species that may replace each other in separate areas of similar habitat only because of geographical isolation. Proponents of local factors find support in the fact that primate population densities predictably increase in areas of greater soil fertility (Peres), high food quality (Janson & Chapman), and low hunting pressure (Peres).