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Constraint and competition in assemblages: a cross continental and modeling approach for ants

Parr, C.L., Sinclair, B.J., Andersen, A.N., Gaston, K.J. and Chown, S.L. (2005) Constraint and competition in assemblages: a cross continental and modeling approach for ants. The American Naturalist, 165 (4). pp. 481-494. ISSN 0003-0147


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The mechanisms leading to structure in local assemblages are controversial. On the one hand, assemblage structure is thought to be the outcome of local interactions determined by the properties of species and their responses to the local environment. Alternatively, this structure has been shown to be an emergent property of assemblages of identical individuals or of random sampling of a regional assemblage.

In ants at baits, a combination of environmental stress and interspecific competition is widely held to lead to a unimodal relationship between the abundance of dominant ants and species richness. It is thought that in comparatively adverse environments, both abundance and richness are low. As habitats become more favorable, abundance increases until the abundance of dominant ants is so high that they exclude those that are subordinate and so depress richness. Here we demonstrate empirically that this relationship is remarkably similar across three continents. Using a null model approach, we then show that the ascending part of the relationship is largely constrained to take this form not simply as a consequence of stress but also as a result of the shape of abundance frequency distributions. While the form of the species-abundance frequency distribution can also produce the descending part of the relationship, interspecific competition might lead to it too. Scatter about the relationship, which is generally not discussed in the literature, may well be a consequence of resource availability and environmental patchiness. Our results draw attention to the significance of regional processes in structuring ant assemblages.

Item Type: Article
Copyright, Publisher and Additional Information: © 2005 by The University of Chicago. Reproduced in accordance with the publisher's self-archiving policy.
Keywords: abundance frequency distribution, assemblage structure, competition, dominance
Institution: The University of Sheffield
Academic Units: The University of Sheffield > Faculty of Science (Sheffield) > School of Biological Sciences (Sheffield) > Department of Animal and Plant Sciences (Sheffield)
Depositing User: Repository Assistant
Date Deposited: 17 Jul 2006
Last Modified: 28 Jul 2016 04:53
Published Version: http://www.journals.uchicago.edu/AN/journal/conten...
Status: Published
Publisher: The University of Chicago Press
Refereed: Yes
URI: http://eprints.whiterose.ac.uk/id/eprint/1442

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