Extinction Dynamics in Experimental Metapopulations

Metapopulation theory provides a framework for understanding population persistence in fragmented landscapes and as such has been widely used in conservation biology to inform management of fragmented populations. However, classical metapopulation theory [Levins, R. (1970) Lect. Notes Math. 2, 75-10...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2005-03, Vol.102 (10), p.3726-3731
Main Authors: Molofsky, Jane, Ferdy, Jean-Baptiste, Levin, Simon A.
Format: Article
Language:English
Subjects:
Animal migration behavior
Biological Sciences
Cardamine pensylvanica
Demography
Depopulation
Ecology
Extinction
Metapopulation ecology
Migration
Modeling
Plant populations
Population Dynamics
Population growth
Population migration
Probability
Risk
Simulations
Species extinction
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Summary:Metapopulation theory provides a framework for understanding population persistence in fragmented landscapes and as such has been widely used in conservation biology to inform management of fragmented populations. However, classical metapopulation theory [Levins, R. (1970) Lect. Notes Math. 2, 75-107] ignores metapopulation structure and local population dynamics, both of which may affect extinction dynamics. Here, we investigate metapopulation dynamics in populations that are subject to different migration rates by using experimental metapopulations of the annual plant Cardamine pensylvanica. As predicted by classical metapopulation theory, connected populations persisted longer than did isolated populations, but the relationship between migration and persistence time was nonlinear. Extinction risk sharply increased as the distance between local populations increased above a threshold value that was consistent with stochastic simulations and calculation of metapopulation capacity [Hanski, I. & Ovaskainen, O. (2000) Nature 404, 755-758]. In addition, the most connected metapopulations did not have the highest persistence levels. Stochastic simulations indicated an increase in extinction risk with the highest migration rates. Moreover, calculation of population coherence [Earn, D. J. D., Levin, S. A. & Rohani, P. (2000) Science 290, 1360-1364], a metric that predicts synchronous cycles, indicated that continuous populations should cycle in phase, resulting in an increased extinction risk. Determining empirically the optimal migration level to improve survival chances will be challenging for any natural population. Migration rates that would not increase migration above the threshold value would be ineffectual, but migration rates that would homogenize local densities could increase the risk of coherent oscillations and enhance extinction risk.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0404576102