The river-refuge hypothesis and other contributions of Marcio Ayres to conservation science

Abstract

Abstract:For more than a century, biogeographers have sought to explain the large number of species found in Amazonian forests. The role of rivers as barriers to dispersal was recognized early on and this was the first evolutionary hypothesis to explain Amazonian diversity. Most of the recent debate on speciation in the Amazon has focused on the role of Pleistocene refugia. The methods of refuge biogeography helped shape early conservation priorities in Amazonia, although actual plans did not directly depend on the conceptual strengths or weaknesses of refugia biogeography.These approaches viewed people mostly as threats, though not always explicitly. Based on his work on primate distribution Marcio Ayres formulated a synthetic speciation theory, the riverrefuge hypothesis. The river-refuge model successfully resolved some of the historical and technical challenges of the earlier hypotheses. His work in varzea conservation, informed by this conceptual brealthrough, recognized that the maintenance of processes is at least as important as species numbers in prioritizing action. The work of Marcio Ayres broadened the scope of conservation in Amazonia by moving beyond the model of people-as-threats, and this as great a conceptual contribution to conservation as anyone could make.