AICME II abstracts

Behaviour-mediated population dynamics

Behaviour-mediated population dynamics

AICME II abstracts

References Evolution restricts the coexistence of specialists and generalists - the role of trade- off structure

[1] Wilson, D.S. & J. Yoshimura. 1994. On the coexistence of specialists and generalists. American Naturalist 144: 692-707.

Martijn Egas1 , Ulf Dieckmann2 and Maurice W. Sabelis3 . In a seminal paper, Wilson and Yoshimura (1994) discussed simulations showing that temporal variability in the environment and adaptive foraging behavior allow for coexistence of specialists and generalists under a wide range of conditions. Here, we challenge this widely cited conclusion by extending the original analysis in three directions. First, we reformulate the model to remove a structural instability, emerging from assumptions on foraging behavior. Second, we consider a wider range of trade- offs for exploiting the two habitats in the model. Third, we address evolutionary attainability and stability of the coexistence of specialists and generalists. Our analysis shows that the potential for coexistence of specialists and generalists is much more restricted than originally thought. Under the original trade-off structure, affecting the carrying capacities, the evolutionarily stable coexistence is non-attainable in most cases. Moreover, the ecological conditions for coexistence become more restricted when the trade-off acts on habitat-specific growth rate rather than on carrying capacity. We conclude that an evolutionarily stable community of specialists and generalists can only be created through migration or mutations of large effect. Our results highlight that trade-offs in fitness-determining traits may have counterintuitive effects on the evolution of specialization when they do not map linearly onto a trade-off in fitness itself. 1 Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94084, 1090 GB, Amsterdam, The Netherlands. Adaptive Dynamics Network, International Institute for Applied Systems Analysis, Schlossplatz 1, 2361 Laxenburg, Austria (e-mail: ). 2 Adaptive Dynamics Network, International Institute for Applied Systems Analysis, Schlossplatz 1, 2361 Laxenburg, Austria. (e-mail: ). 3 Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94084, 1090 GB, Amsterdam, The Netherlands (e-mail: ).

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