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  • 1.
    de Roos, André M.
    et al.
    Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94084, 1090 GB Amsterdam, The Netherlands.
    Schellekens, Tim
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Van Kooten, Tobias
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Persson, Lennart
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Stage-specific predator species help each other to persist while competing for a single prey2008In: Proceedings from the National Academy of Science of the United States of America, ISSN 0027-8424, EISSN 1091-6490, Vol. 105, no 37, p. 13930-13935Article in journal (Refereed)
    Abstract [en]

    Prey in natural communities are usually shared by many predator species. How predators coexist while competing for the same prey is one of the fundamental questions in ecology. Here we show that competing predator species may not only coexist on a single prey but even help each other to persist, if they specialize on different life history stages of the prey. By changing the prey size distribution a predator species may in fact increase the amount of prey available for its competitor. Surprisingly, a predator may even not be able to persist at all unless its competitor is also present. The competitor thus increases significantly the range of conditions for which a particular predator can persist. This “emergent facilitation” is a long-term, population-level effect that results from asymmetric increases in the rate of prey maturation and reproduction when predation relaxes competition among prey. Emergent facilitation explains observations of correlated increases of predators on small and large conspecific prey as well as concordance in their distribution patterns. Our results suggest that emergent facilitation may promote the occurrence of complex, stable community food webs and that persistence of these communities could critically depend on diversity within predator guilds.

  • 2.
    de Roos, André M
    et al.
    Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O.Box 94084, 1090 GB Amsterdam, The Netherlands.
    Schellekens, Tim
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    van Kooten, Tobias
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    van de Wolfshaar, Karen
    Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O.Box 94084, 1090 GB Amsterdam, The Netherlands.
    Claessen, David
    Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O.Box 94084, 1090 GB Amsterdam, The Netherlands.
    Persson, Lennart
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Food-dependent growth leads to overcompensation in stage-specific biomass when mortality increases: the influence of maturation versus reproduction regulation2007In: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 170, no 3, p. E59-E76Article in journal (Refereed)
  • 3.
    De Roos, André M
    et al.
    Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O.Box 94084, 1090 GB Amsterdam, The Netherlands.
    Schellekens, Tim
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Van Kooten, Tobias
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Van De Wolfshaar, Karen
    Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O.Box 94084, 1090 GB Amsterdam, The Netherlands.
    Claessen, David
    Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O.Box 94084, 1090 GB Amsterdam, The Netherlands.
    Persson, Lennart
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Simplifying a physiologically structured population model to a stage-structured biomass model.2008In: Theoretical Population Biology, ISSN 0040-5809, E-ISSN 1096-0325, Vol. 73, no 1, p. 47-62Article in journal (Refereed)
    Abstract [en]

    We formulate and analyze an archetypal consumer-resource model in terms of ordinary differential equations that consistently translates individual life history processes, in particular food-dependent growth in body size and stage-specific differences between juveniles and adults in resource use and mortality, to the population level. This stage-structured model is derived as an approximation to a physiologically structured population model, which accounts for a complete size-distribution of the consumer population and which is based on assumptions about the energy budget and size-dependent life history of individual consumers. The approximation ensures that under equilibrium conditions predictions of both models are completely identical. In addition we find that under non-equilibrium conditions the stage-structured model gives rise to dynamics that closely approximate the dynamics exhibited by the size-structured model, as long as adult consumers are superior foragers than juveniles with a higher mass-specific ingestion rate. When the mass-specific intake rate of juvenile consumers is higher, the size-structured model exhibits single-generation cycles, in which a single cohort of consumers dominates population dynamics throughout its life time and the population composition varies over time between a dominance by juveniles and adults, respectively. The stage-structured model does not capture these dynamics because it incorporates a distributed time delay between the birth and maturation of an individual organism in contrast to the size-structured model, in which maturation is a discrete event in individual life history. We investigate model dynamics with both semi-chemostat and logistic resource growth.

  • 4. van Kooten, T
    et al.
    De Roos, A M
    Persson, L
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Local foraging and limited mobility: Dynamics of a size-structured consumer population2004In: Ecology, Vol. 85, p. 1979-1991Article in journal (Refereed)
  • 5.
    van Kooten, Tobias
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    de Roos, André M
    Persson, Lennart
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Bistability and an Allee effect as emergent consequences of stage-specific predation.2005In: J Theor Biol, ISSN 0022-5193, Vol. 237, no 1, p. 67-74Article in journal (Refereed)
  • 6.
    van Kooten, Tobias
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Persson, Lennart
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    de Roos, André M.
    Population dynamical consequences of gregariousness in a size-structured consumer–resource interaction2007In: Journal of Theoretical Biology, Vol. 254, no 4, p. 763-774Article in journal (Refereed)
    Abstract [en]

    Many animal species live in groups. Group living may increase exploitation competition within the group, and variation among groups in intra-group competition intensity could induce life-history variability among groups. Models of physiologically structured populations generally predict single generation cycles, driven by exploitation competition within and between generations. We expect that life-history variability and habitat heterogeneity induced by group living may affect such competition-driven population dynamics. In this study, we vary the gregariousness (the tendency to aggregate in groups) of a size-structured consumer population in a spatially explicit environment. The consumer has limited mobility, and moves according to a probabilistic movement process. We study the effects on the population dynamics, as mediated through the resource and the life-history of the consumer. We find that high gregariousness leads to large spatial resource variation, and highly variable individual life-history, resulting in highly stochastic population dynamics. At reduced gregariousness, life-history of consumers synchronizes, habitat heterogeneity is reduced, and single generation cycles appear. We expect this pattern to occur for any group living organism with limited mobility. Our results indicate that constraints set by population dynamical feedback may be an important aspect in understanding group living in nature.

  • 7.
    van Kooten, Tobias
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Persson, Lennart
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    de Roos, André M
    Size-Dependent Mortality Induces Life-History Changes Mediated through Population Dynamical Feedbacks2007In: American Naturalist, Vol. 170, no 2, p. 258-270Article in journal (Refereed)
    Abstract [en]

    The majority of taxa grow significantly during life history, which often leads to individuals of the same species having different ecological roles, depending on their size or life stage. One aspect of life history that changes during ontogeny is mortality. When individual growth and development are resource dependent, changes in mortality can affect the outcome of size-dependent intraspecific resource competition, in turn affecting both life history and population dynamics. We study the outcome of varying size-dependent mortality on two life-history types, one that feeds on the same resource throughout life history and another that can alternatively cannibalize smaller conspecifics. Compensatory responses in the life history dampen the effect of certain types of size-dependent mortality, while other types of mortality lead to dramatic changes in life history and population dynamics, including population (de-)stabilization, and the growth of cannibalistic giants. These responses differ strongly among the two life-history types. Our analysis provides a mechanistic understanding of the population-level effects that come about through the interaction between individual growth and size-dependent mortality, mediated by resource dependence in individual vital rates.

1 - 7 of 7
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