OOS 46-8 - Well-connected but empty on the inside: Active dispersal can reduce the species richness of accessible habitat patches

Friday, August 7, 2009: 10:30 AM
Blrm B, Albuquerque Convention Center
Gareth J. Russell , Federated Department of Biological Sciences, New Jersey Institute of Technology and Rutgers University, Newark, NJ
James I. Watling , Ft Lauderdale Research and Education Center, University of Florida, Ft Lauderdale, FL
Tomás Santos , Departamento de Zoología y Antropología Física, Universidad Complutense, Madrid, Spain
José Luis Tellería , Departamento de Zoología y Antropología Física, Universidad Complutense, Madrid, Spain
Karina Aliaga , Mathematical Sciences, New Jersey Institute of Technology, Newark, NJ
Temipote Brotherson , Mathematical Sciences, New Jersey Institute of Technology, Newark, NJ
Background/Question/Methods We modify MacArthur and Wilson's theory of island biogeography, which implicitly assumes ‘passive' dispersal and population dynamics, by adding choice-based immigration and emigration functions that both vary with isolation. We fit the models to a large number of existing biogeographic datasets. Results/Conclusions We show that in many cases, the modified models are preferable to the original model even given their increased complexity. For many datasets involving birds, there is evidence for a strong tendency to leave those patches that are closest to larger patches — a tendency that overwhelms the original model's assumption of a higher (passive) colonization rate and results in expectedly impoverished species richness. If real, this phenomenon has disturbing implications for conservation-oriented landscape planning. Habitat corridors, in particular, might in some circumstances have the opposite effect from the one intended, leaving connected fragments worse off than before.
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