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Diatom β‐diversity in streams increases with spatial scale and decreases with nutrient enrichment across regional to sub‐continental scales
Author(s) -
Leboucher Thibault,
Budnick William R.,
Passy Sophia I.,
Boutry Sébastien,
Jamoneau Aurélien,
Soininen Janne,
Vyverman Wim,
TisonRosebery Juliette
Publication year - 2019
Publication title -
journal of biogeography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 158
eISSN - 1365-2699
pISSN - 0305-0270
DOI - 10.1111/jbi.13517
Subject(s) - gamma diversity , ecology , beta diversity , biological dispersal , alpha diversity , nutrient , biodiversity , spatial ecology , species diversity , environmental science , diatom , species richness , diversity (politics) , spatial heterogeneity , spatial variability , biology , geography , population , statistics , anthropology , mathematics , demography , sociology
Abstract Aim To quantify the relative contributions of local community assembly processes versus γ‐diversity to β‐diversity, and to assess how spatial scale and anthropogenic disturbance ( i.e . nutrient enrichment) interact to dictate which driver dominates. Location France and the United States. Time period 1993–2011. Major taxa studied Freshwater stream diatoms. Methods β‐diversity along a nutrient enrichment gradient was examined across multiple spatial scales. β‐diversity was estimated using multi‐site Sørensen dissimilarity. We assessed the relative importance of specialists versus generalists using Friedley coefficient, and the contribution of local community assembly versus γ‐diversity to β‐diversity across spatial scales, with a null model. Finally, we estimated the response of β‐diversity to environmental and spatial factors by testing the correlations between community, environmental and geographical distance matrices with partial Mantel tests. Results β‐diversity generally increased with spatial scale but the rate of increase depended on nutrient enrichment level. β‐diversity decreased significantly with increasing nutrient enrichment level due to the loss of specialist species. Local assembly was an important driver of β‐diversity especially under low nutrient enrichment. Significant partial Mantel correlations were observed between diatom β‐diversity and pure environmental distances under these conditions, highlighting the role of species sorting in local assembly processes. Conversely, in heavily enriched sites, only spatial distances were significantly correlated with β‐diversity, which indicated a substantial role of dispersal processes. Main conclusions Nutrient concentration mediated the expected increase in β‐diversity with spatial scales. Across spatial scales, β‐diversity was more influenced by local assembly processes rather than by γ‐diversity. Nutrient enrichment was associated with an overall decline in diatom β‐diversity and a shift in assembly processes from species sorting to dispersal, notably due to the elimination of some specialists and their subsequent replacement by generalists.