Granivory in the southern South American deserts: conceptual issues and current evidence

Abstract

Ecologists have abandoned attempts to develop a simple, unifying theory to account for community patterns (Lawton 1999). Instead, to explain such patterns, they rely on local ecological processes as well as on more contingent historical processes acting at large temporal and spatial scales (e.g., unique historical events controlling speciation and biogeographic interchanges). This mixed approach should lead to a more realistic idea of the real world, but it deserves careful epistemological consideration. Although historical hypotheses may account for a substantial part of community patterns, they impose limits to theory development because they deal with contingent events that may often be theoretically intractable. An ecological system may be unique, but this does not necessarily imply that it is lawless in the ontological sense. Consequently, the methodological problem remains of distinguishing its general properties from its idiosyncratic properties (Mahner and Bunge 1997). Historical explanations also impose limits to hypothesis testing because they often do not make predictions and can be elucidated solely by historical reconstruction (Schluter and Ricklefs 1993).