AN INTEGRATIVE FRAMEWORK OF COEXISTENCE MECHANISMS IN COMPETITIVE METACOMMUNITIES
Fournier, B.,Mouquet, N., Leibold, M.A., Gravel, D.(2017).
Key message : We present a new model of metacommunity dynamics that simultaneously considers these four possible mechanisms over spatially explicit landscapes and propose a statistical approach to partition their contribution to species distribution. We find that landscape configuration can induce dispersal limitations that have negative consequences for local species richness. This result was more pronounced with neutral dynamics and mass effect than with species sorting or patch dynamics. We also find that the relative importance of the four mechanisms varies not only among landscape configurations, but also among species, with some species being mostly constrained by dispersal and/or drift and others by sorting. Changes in landscape properties might lead to a shift in coexistence mechanisms and, by extension, to a change in community composition. This confirms the importance of considering landscape properties for conservation and management.
Simplified description of the model. (a) Hypothetical landscape composed by four patches and including environmental heterogeneity. Kij is a dispersal kernel based on the distance among sites. Two patches are considered connected when Kij is lower than a threshold Euclidean distance of r. The lower panel shows the connectivity among sites as an adjacency matrix where 1 indicates connected sites and 0 un-connected ones. (b) Competitive ability (Cix), propagule production (Fix) and extinction probability (Wix) as a function of environmental conditions for species A (solid black line) and species B (dashed grey line). In our example, species A and B have equal maximal performance and niche breadth for competitive ability and propagule production, but have different environmental optima. As a result, species A is a better competitor in sites 1 and 3 (green dot) whereas species B outcompetes species A in sites 2 and 4 (orange dot). (c) Local dynamic in the case of an empty site and in the case of a site already occupied by species A. The probability that species A can colonize an empty site depends on its recruitment probability (Iix) and the probability that a superior competitor colonizes the empty patch (Rix). When species A is present at a site, it can die depending on its extinction probability (Wix) leaving the site empty or be replaced by a superior competitor (as a function of Rix).
OTHER TOPICS: Aesthetics of Biodiversity, Biodiversity & Ecosystem Functioning, Biogeography, Macroecology & Ecophylogenetics, Experimental Evolution,
Functional Biogeography, Functional Rarity, Metacommunities, Metaecosystems, Reviews and Synthesis, Trophic Biogeography & Metaweb