The form of species-abundance distributions |
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Authors: | RD Routledge |
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Institution: | Department of Mathematics, University of Alberta, Edmonton, Alberta, T6G 2G1, Canada |
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Abstract: | Small, isolated communities in harsh environments are sometimes found to contain many, very rare species together with a few, extremely abundant ones. The species-abundance distribution (frequencies of species vs. abundance levels) drops rapidly from an initial peak to an elongated tail. A distribution with similar form is also predicted by a model of resource apportioning. This concurrence has been viewed by some as evidence of the accuracy of the model. However, it is shown here that such a form is to be expected whenever species abundances are not influenced greatly by either immigration or density-dependent regulation.The species-abundance distribution in larger communities is often found to increase initially to a mode, and then decrease to an elongated tail. This form is also to be expected whenever each species in the larger “community” consists of a substantial number of roughly independent populations. |
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