Evol Ecol Res 16: 445-460 (2014) Full PDF
Robustness of the spatial insurance effects of biodiversity to habitat loss
Patrick L. Thompson*, Bronwyn Rayfield* and Andrew Gonzalez
Department of Biology, McGill University, Montreal, Quebec, Canada
Correspondence: A. Gonzalez, Department of Biology, McGill University, Stewart Biology Building N3/2, Montreal, Quebec H3A 1B1, Canada.
Definitions: Spatial insurance: Improvement of maintenance of species diversity and ecosystem functioning in heterogeneous environments because species can track their optimal environments by dispersing between habitat patches. Betweenness centrality: Value of an individual habitat patch in adding to the connectivity of the metacommunity by being a stepping-stone for dispersing individuals. Robustness: The proportion of patches that must be removed to change each response variable beyond a given threshold.
Question: In fragmented landscapes, how do spatial patterns of habitat loss affect the robustness of the insurance effects on biodiversity? Does the underlying pattern of habitat connectivity in metacommunities play a role in maintaining biodiversity and ecosystem function in the face of habitat loss?
Mathematical method: Using a spatially explicit version of a resource competition metacommunity model, we simulated habitat loss in metacommunity networks composed of habitat patches connected by links for dispersal.
Key assumptions: Species differ in their environmental preferences. Local environmental conditions fluctuate asynchronously so that species must disperse in order to persist and maintain productivity. Habitat patches are lost sequentially, resulting in gradual fragmentation of the metacommunity.
Results: Habitat loss reduces the amount of spatial insurance conferred by the habitat structure on biodiversity by preventing species from dispersing to environmentally suitable areas. The robustness of metacommunities to habitat loss decreases dramatically when the patches with high betweenness centrality are lost. Metacommunities are generally most robust when the pattern of habitat connectivity is random and when the habitat patches that are lost have low betweenness centrality.
Keywords: centrality, connectivity, dispersal, ecosystem function, environmental change, extinction, habitat fragmentation, metacommunity, network, stability.
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