THE ROLE OF ECOLOGICAL KNOWLEDGE IN EXPLAINING BIOGEOGRAPHY AND BIODIVERSITY IN AMAZONIA

Biogeographical studies in Amazonia have commonly taken a historical, rather than an ecological approach. General patterns have been sought in the distribution maps of different species, and these have been exp lained in terms of past or present distribution barriers, especially p ast climates and large rivers. Implicitly, and often also explicitly, it is assumed that Amazonia is ecologically so uniform that present-da y ecological conditions are rather insignificant in determining specie s distribution patterns and speciation. However, this assumption is mo re based on the lack of relevant data than on actual observations of e nvironmental uniformity or ecological unspecialization of the species. Recent studies have indeed documented ecological heterogeneity and fl oristic differences among sites that were previously thought similar. In the absence of direct knowledge of the past, more complete ecologic al and environmental understanding of the present-day Amazonia are nee ded for evaluating the relative roles of historical and ecological fac tors in Amazonian biogeography and biodiversity.