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Interactions among mutualism, competition, and predation foster species coexistence in diverse communities

Theoretical Ecology volume 8, pages 297–312 (2015)Cite this article

Abstract

In natural systems, organisms are simultaneously engaged in mutualistic, competitive, and predatory interactions. Theory predicts that species persistence and community stability are feasible when the beneficial effects of mutualisms are balanced by density-dependent negative feedbacks. Enemy-mediated negative feedbacks can foster plant species coexistence in diverse communities, but empirical evidence remains mixed. Disparity between theoretical expectations and empirical results may arise from the effects of mutualistic mycorrhizal fungi. Here, we build a multiprey species/predator model combined with a bidirectional resource exchange system, which simulates mutualistic interactions between plants and fungi. To reach population persistence, (1) the per capita rate of increase of all plant population must exceed the sum of the negative per capita effects of predation, interspecific competition, and costs of mycorrhizal association, and (2) the per capita numerical response of enemies to mycorrhizal plants must exceed the magnitude of the per capita enemy rate of mortality. These conditions reflect the balance between regulation and facilitation in the system. Interactions between plant natural enemies and mycorrhizal fungi lead to shifts in the strength and direction of net mycorrhizal effects on plants over time, with common plant species deriving greater benefits from mycorrhizal associations than rare plant species.

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Acknowledgments

Benedicte Bachelot was partially supported with funds from National Science Foundation DEB-524989 to MU. We are grateful to Dr. Agnes Bachelot, Dr. Alain Bachelot, Dr. Duncan Menge, Dr. Jason Hoeksema, Dr. Stefano Allesina, Dr. Samir Suweis, Dr. Charlotte Lee, Rachael Eaton, Benton Taylor, Bob Muscarella, Naomi Schwartz, and anonymous reviewers for useful comments on the manuscript. In particular, we are grateful to Axios Review that greatly helped us improve our manuscript.

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  1. Department of Ecology, Evolution and Environmental Biology, Columbia University, 1200 Amsterdam Avenue, New York, NY, 10027, USA

    Benedicte Bachelot & María Uriarte

  2. Department of Biology, Barnard College, Columbia University, New York, NY, 10027, USA

    Krista McGuire

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  1. Benedicte Bachelot
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  2. María Uriarte
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Correspondence to Benedicte Bachelot.

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Bachelot, B., Uriarte, M. & McGuire, K. Interactions among mutualism, competition, and predation foster species coexistence in diverse communities. Theor Ecol 8, 297–312 (2015). https://doi.org/10.1007/s12080-015-0251-2

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Keywords

  • Prey–predator model
  • Food web dynamics
  • Mutualism
  • Janzen-Connell
  • Mycorrhizal associations