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Local and regional drivers of taxonomic homogenization in stream communities along a land use gradient.

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Budnick, William R.; Leboucher, Thibault; Belliard, Jérôme; Soininen, Janne; Lavoie, Isabelle; Pound, Katrina; Jamoneau, Aurélien; Tison‐Rosebery, Juliette; Tales, Evelyne; Pajunen, Virpi; Campeau, Stéphane; Passy, Sophia I.; Bahn, Volker (2019). Local and regional drivers of taxonomic homogenization in stream communities along a land use gradient. Global Ecology and Biogeography , vol. 28 , nº 11. p. 1597-1609. DOI: 10.1111/geb.12976.

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Résumé

Aim

The interaction of land use with local versus regional processes driving biological homogenization (β‐diversity loss) is poorly understood. We explored: (a) stream β‐diversity responses to land cover (forest versus agriculture) in terms of physicochemistry and physicochemical heterogeneity; (b) whether these responses were constrained by the regional species pool, i.e. γ‐diversity, or local assembly processes through local (α) diversity; (c) whether local assembly operated through the regional species abundance distribution (SAD) or intraspecific spatial aggregation; and (d) the dependence on body size, dispersal capacity and trophic level (producer versus consumer).

Location

USA, Canada and France.

Time period

1993–2012.

Major taxa studied

Stream diatoms, insects and fish.

Methods

We analysed six datasets totalling 1,225 stream samples. We compared diversity responses to eutrophication and physicochemical heterogeneity in forested versus agricultural streams with regression methods. Null models quantified the contribution of local assembly to β‐diversity (β‐deviance, βDEV) for both types of land covers and partitioned it into fractions explained by the regional SAD (βSAD) versus aggregation (βAGG).

Results

Eutrophication explained homogenization and more uneven regional SADs across groups, but local and regional biodiversity responses differed across taxa. The βDEV was insensitive to land use. The βSAD largely exceeded βAGG and was higher in agriculture.

Main conclusions

Eutrophication but not physicochemical heterogeneity of agricultural streams underlay β‐diversity loss in diatoms, insects and fish. Agriculture did not constrain the magnitude of local versus regional effects on β‐diversity but controlled the local assembly mechanisms. Although the SAD fraction dominated in both land covers, it increased further in agriculture at the expense of aggregation. Notably, the regional SADs were more uneven in agriculture, exhibiting excess common species or stronger dominance. Diatoms and insects diverged from fish in terms of biodiversity, SAD shape and βDEV patterns, suggesting an overriding role of body size and/or dispersal capacity compared with trophic position.

Type de document: Article
Mots-clés libres: β‐diversity; biodiversity loss; diatoms; fish; insects; land use; local assembly; spatial aggregation; species abundance distribution; taxonomic homogenization
Centre: Centre Eau Terre Environnement
Date de dépôt: 29 nov. 2019 14:06
Dernière modification: 29 nov. 2019 14:06
URI: http://espace.inrs.ca/id/eprint/9549

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