TREE-1506; No. of Pages 2 Letter The terminology of metacommunity ecology Amanda K. Winegardner1,2,3, Brittany K. Jones1, Ingrid S.Y. Ng1, Tadeu Siqueira1,4 and Karl Cottenie1 1 Department of Integrative Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario, N1G 2W1, Canada Churchill Northern Studies Centre, Launch Road, Churchill, Manitoba, R0B 0E0, Canada 3 Department of Biology, McGill University, 1205 Avenue Docteur Penfield, Montreal, Quebec, H3A 1B1, Canada 4 Departamento de Ecologia, Universidade Estadual Paulista, Rio Claro, SP, CP 199, Brazil 2 One of the most promising theoretical frameworks for studying responses to ecological change is the metacommunity concept. Recent work by Logue et al. [1] provided the first comprehensive synthesis of empirical metacommunity research since the seminal work by Leibold et al. published in 2004 [2]. In their original work [2], Leibold et al. outlined the theoretical framework for the study of a metacommunity, a set of local communities connected by dispersing species. Logue et al. [1] point out some of the limitations of the original concept as well as more recent research. More importantly, they make three recommendations for future research in metacommunity ecology to continue to advance this field: (i) the extension of empirical approaches to different and varied metacommunity systems; (ii) the integration of established metacommunity paradigms; and (iii) work incorporating meta-ecosystem and evolutionary mechanisms. These are important recommendations, but we think that their second recommendation is a necessary condition for the other two. We propose that a revision of the terminology used by Leibold et al. [2] can already accomplish part of this integration. Leibold et al. [2] proposed four paradigms of metacommunities: (i) neutral model; (ii) patch dynamics; (iii) mass effects; and (iv) species sorting, synthesizing concepts of intra- and intercommunity dynamics [2]. These four paradigms have formed the basis for the modern metacommunity concept, and much literature has characterized metacommunities based on the degree to which the systems conform to these paradigms (e.g. [2]). What the terminology of Leibold et al. [2] does not explicitly recognize is that two of these metacommunity paradigms (mass effects and patch dynamics) are actually special cases of the species-sorting paradigm. In the patch dynamics paradigm, the interacting species differ from each other, but in a very specific way. They specialize in their abilities as either competitors or colonizers within a uniform environment. Patches of varying species composition develop as species effectively colonize a site or outcompete other species. A second, less described, type of patch dynamics starts from a species-sorting setting, with environmental heterogeneity and associated species differences. Strong priority effects in such a system caused by dispersal limitation can lead to different and stable communities [3]. For the mass effects paradigm, source– sink dynamics enable species to exist at sites normally considered marginal or outside of their environmental range because high dispersal ensures a constant supply of new Corresponding author: Winegardner, A.K. (amanda.winegardner@gmail.com). colonizers to these sites [2]. Therefore, these species have very different niche requirements, essentially a speciessorting framework, but dispersal maintains species in sites with negative growth rates. The only way to detect mass effects truly is to model or measure population growth rates of a species in an environment with and without dispersal. Thus, the distinguishing feature of a patch dynamic versus a species-sorting versus a mass effect framework is the amount of dispersal present between communities within a metacommunity: dispersal is limiting for some of the species in the patch dynamic framework, efficient for (the majority of) the species in a species-sorting framework, and high for some of the species in the mass effect framework. The terminology used by Leibold et al. [2] ensures consistency with the previous concepts in the literature. For example, terms such as ‘patch dynamics’ or ‘mass effects’ were already well documented in the literature before this work (e.g. [3–7]). Although we doubt that it was the intention of Leibold et al. [2] to suggest that these four paradigms were mutually exclusive or that each metacommunity system was uniquely associated with a single paradigm, the summary of research provided by Logue et al. [1] shows that work since 2004 has largely focused on delineating between the four paradigms (e.g. [8]). Indeed, Logue et al. [1] showed that the majority of observational metacommunity studies were aimed at testing for patch dynamics or mass effects. Thus, the terminology of the four paradigms ensures consistency over time, but continuing to use these terms while not explicitly recognizing, for instance, that patch dynamics and mass effects are special cases of the species-sorting paradigm does not address the actual relationships between the different paradigms. More importantly, these relationships illustrate the fundamental mechanistic processes responsible for metacommunities. We suggest that ecologists could move on from characterizing metacommunities as ‘species sorting’, ‘patch dynamics’, ‘mass effects’ or ‘neutral model’. Rather, they should break these paradigms down and go back to the basics of thinking about what these paradigms mean for dispersal and environmental signals in metacommunities. This avoids the issue of having four discrete paradigms, and rather puts the focus on the relationships at play in metacommunities and how the mechanisms behind the patterns that describe each of the paradigms interact in a metacommunity. We thus propose to think about metacommunities as neutral, and species sorting with limiting (patch dynamics, sensu [2]), 1 TREE-1506; No. of Pages 2 Letter efficient (species sorting, sensu [2]), and high dispersal (mass effects, sensu [2]) as these terms capture the causal mechanisms and are, thus, more explicit. Acknowledgments We thank Kyle Gillespie for comments on these early thoughts, as well as the classes of BIOL 3120– Community Ecology at the University of Guelph for showing us how to explain metacommunity ecology to a broad audience. References 1 Logue, J.B. et al. (2011) Empirical approaches to metacommunities: a review and comparison with theory. Trends Ecol. Evol. 26, 482–491 2 Leibold, M.A. et al. (2004) The metacommunity concept: a framework for multi-scale community ecology. Ecol. Lett. 7, 601–613 2 Trends in Ecology and Evolution xxx xxxx, Vol. xxx, No. x 3 Shurin, J.B. et al. (2004) Alternative stable states and regional community structure. J. Theor. Biol. 227, 359–368 4 Levins, R. and Culver, D. (1971) Regional coexistence of species and competition between rare species. Proc. Natl. Acad. Sci. U.S.A. 68, 1246– 1248 5 Brown, J.H. and Kodric-Brown, A. (1977) Turnover rates in insular biogeography: effect of immigration on extinction. Ecology 58, 445–449 6 Schmida, A. and Wilson, M.V. (1985) Biological determinants of species diversity. J. Biogeogr. 12, 1–20 7 Yu, D.W. et al. (2001) An empirical model of species coexistence in a spatially structured environment. Ecology 82, 1761–1771 8 Cottenie, K. (2005) Integrating environmental and spatial processes in ecological community dynamics. Ecol. Lett. 8, 1175–1182 0169-5347/$ – see front matter ß 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.tree.2012.01.007 Trends in Ecology and Evolution xx (2012) 1–2