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International Journal of Ecology
Volume 2012 (2012), Article ID 725487, 11 pages
http://dx.doi.org/10.1155/2012/725487
Research Article

How Facilitation May Interfere with Ecological Speciation

1Department of Biology, University of Pennsylvania, 322 Leidy Labs, Philadelphia, PA 19104, USA
2Department of Plant Ecology, University of Tübingen, Auf der Morgenstelle 3, 72072 Tübingen, Germany
3Laboratoire d'Ecologie Alpine, CNRS UMR 5553, Université de Grenoble, BP 53, 38041 Grenoble, France
4Station Alpine J. Fourier, CNRS UMS 2925, Université de Grenoble, 38041 Grenoble, France
5INRA, USC Agripop (CEBC-CNRS), 79360 Beauvoir sur Niort, France
6CEBC-CNRS (UPR 1934), 79360 Beauvoir sur Niort, France
7National Institute for Mathematical and Biological Synthesis (NIMBioS), University of Tennessee, 1534 White Avenue, Suite 400, Knoxville, TN 37996, USA

Received 13 July 2011; Revised 15 November 2011; Accepted 10 December 2011

Academic Editor: Rui Faria

Copyright © 2012 P. Liancourt et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Compared to the vast literature linking competitive interactions and speciation, attempts to understand the role of facilitation for evolutionary diversification remain scarce. Yet, community ecologists now recognize the importance of positive interactions within plant communities. Here, we examine how facilitation may interfere with the mechanisms of ecological speciation. We argue that facilitation is likely to (1) maintain gene flow among incipient species by enabling cooccurrence of adapted and maladapted forms in marginal habitats and (2) increase fitness of introgressed forms and limit reinforcement in secondary contact zones. Alternatively, we present how facilitation may favour colonization of marginal habitats and thus enhance local adaptation and ecological speciation. Therefore, facilitation may impede or pave the way for ecological speciation. Using a simple spatially and genetically explicit modelling framework, we illustrate and propose some first testable ideas about how, when, and where facilitation may act as a cohesive force for ecological speciation. These hypotheses and the modelling framework proposed should stimulate further empirical and theoretical research examining the role of both competitive and positive interactions in the formation of incipient species.