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Preemption of space can lead to intransitive coexistence of competitors

Authors

  • Kyle F. Edwards,

    1. Dept of Evolution and Ecology and Center for Population Biology, Univ. of California Davis, One Shields Ave., Davis, CA 95616, USA
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  • Sebastian J. Schreiber

    1. Dept of Evolution and Ecology and Center for Population Biology, Univ. of California Davis, One Shields Ave., Davis, CA 95616, USA
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K. F. Edwards, Dept of Evolution and Ecology and Center for Population Biology, Univ. of California Davis, One Shields Ave., Davis, CA 95616, USA. E-mail: kedwards@ucdavis.edu

Abstract

Intransitive competition has the potential to be a powerful contributor to species coexistence, but there are few proposed biological mechanisms that could create intransitivities in natural communities. Using a three-species model of competition for space, we demonstrate a mechanism for coexistence that combines a colonization–competition tradeoff between two species with the ability of a third species to preempt space from the other competitors. The combination of differential abilities to colonize, preempt, and overtake space creates a community where no single species can exclude both of its competitors. The dynamics of this kind of community are analogous to rock-paper-scissors competition, and the three-species community can persist even though not all pairs of species can coexist in isolation. In distinction to prior results, this is a mechanism of intransitivity that does not require nonhierarchical local interference competition. We present parameter estimates from a subtidal marine community illustrating how documented competitive traits can lead to preemption-based intransitivities in natural communities, and we describe methods for an empirical test of the occurrence of this mechanism.

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