94th ESA Annual Meeting (August 2 -- 7, 2009)

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. Russell1, James I. Watling2, Tomás Santos3, José Luis Tellería3, Karina Aliaga4 and Temipote Brotherson4, (1)Federated Department of Biological Sciences, New Jersey Institute of Technology and Rutgers University, Newark, NJ, (2)Fort Lauderdale Research and Education Center, University of Florida, Fort Lauderdale, FL, (3)Departamento de Zoología y Antropología Física, Universidad Complutense, Madrid, Spain, (4)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.