Evol Ecol Res 1: 1-1 (1999)     Full PDF if your library subscribes.

Has the ghost of competition passed?

Douglas W. Morris

Department of Biology and Faculty of Forestry and the Forest Environment, Lakehead University, Thunder Bay, Ontario P7B 5E1, Canada

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Theories of density-dependent habitat selection suggest that habitat-selecting competitors may stably co-exist in separate habitats with no competition (the ghost of competition past). The habitat distribution, and hence the value of the non-linear competition coefficients, depends on the joint densities of the competing species. I extend the theories to illustrate how non-linear effects arise from constant habitat-dependent competition. The habitat effect is easily estimated from census data by the use of habitat isodars (lines along which expected fitness is identical in both habitats). The isodar solutions not only reveal the ghost of competition, they can be used as a convenient assay for conditions of stable competitive co-existence and they allow calculation of the actual competition coefficients. The shapes of empirical isoclines are in general agreement with the theoretical predictions.

Keywords: co-existence, competition, ghost of competition, habitat selection, isocline, isodar, isoleg.

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        © 1999 Douglas W. Morris. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.

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