Reconceptualising the beta diversity-environmental heterogeneity relationship in running water systems
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Data
2014-11-11
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Resumo
Beta diversity modelling has received increased interest recently. There are multiple definitions of
beta diversity, but here, we focus on variability in species composition among sampling units within
a given area. This facet can be described using various approaches. Some approaches ignore the spatial
scale of the area considered (i.e. region limits), while some consider different region limits as a
starting point for the analysis of beta diversity.
2. We focused specifically on the beta diversity–environmental heterogeneity relationship in running
waters. First, we present two conceptual models, which assume either (1) strong environmental control
among localities (riffle sites in our case) within each region unit (a region unit encompasses a
species pool and can be a stream or a basin or an ecoregion) or (2) that the spatial level of a region
unit affects the relative importance of mechanisms affecting variability in species composition among
localities (i.e. among riffle sites) within each region unit. Second, we compared three recent studies
that used similar methods to examine the beta diversity–environmental heterogeneity relationship,
but which were based on different region units, comprising sets of streams or sets of basins or sets of
ecoregions.
3. Our conceptual framework assumes that environmental control is not likely to be the sole mechanism
affecting variability in community composition among localities within each region unit, but it
is likely to be most important when dispersal rates are intermediate (i.e. among localities within a
basin). In contrast, if dispersal rates are very high (i.e. among localities within a stream) or very low
(i.e. among localities within an ecoregion), environmental control is in part masked by high dispersal
rates or is prevented from occurring because not all species can reach all localities, respectively. Such
scale dependency in the relative strength of environmental control might therefore transcend spatial
scales from individual region units to the strength of the beta diversity–environmental heterogeneity
relationship. We emphasise that the beta diversity–environmental heterogeneity relationship can only
be tested across multiple region units. The results of three case studies are consistent with these predictions.
Specifically, the beta diversity–environmental heterogeneity regression was highly significant
across multiple basins, but not across multiple streams or across multiple ecoregions.
4. We suggest that researchers take spatial scale and region unit level explicitly into account when
inferring the mechanisms structuring ecological communities and mapping variation in beta diversity.
We also propose a unified terminology for studies examining the beta diversity–environmental
heterogeneity relationship in running waters because inconsistent terminology is likely to hamper
the progress of our science.
Descrição
v. 60, p. 223-235, 2015.
Palavras-chave
Average distance to centroid, Dispersal, Spatial scale, Species sorting, Terminology
Citação
HEINO, Jani; MELO, Adriano S.; BINI, Luis M. Reconceptualising the beta diversity-environmental heterogeneity relationship in running water systems. Freshwater Biology, v. 60, p. 223-235, 2015. Disponível em: < http://onlinelibrary.wiley.com/doi/10.1111/fwb.12502/epdf>.