Fragmentation promotes the role of dispersal in determining 10 intermittent headwater stream metacommunities

Dispersal, defined as the movement of individuals among local communities in a landscape, is a central regional determinant of metacommunity dynamics in ecosystems. Whereas both natural and anthropogenic ecosystem fragmentations can limit dispersal, previous attempts to measure such limitations have...

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Vydáno v:	Freshwater biology Ročník 65; číslo 12; s. 2169 - 2185
Hlavní autoři:	Gauthier, Maïlys, Launay, Bertrand, Le Goff, Guillaume, Pella, Herve, Douady, Christophe J., Datry, Thibault
Médium:	Journal Article
Jazyk:	angličtina
Vydáno:	Oxford Wiley Subscription Services, Inc 01.12.2020 Wiley
Témata:	Anthropogenic factors Aquatic ecosystems Biodiversity Biodiversity and Ecology Community Creeks & streams Dispersal Dispersion distance decays Drying Dynamics Ecosystem services Ecosystems Environmental Sciences extinction Filtration Fragmentation Freshwater Freshwater ecosystems global change Headwaters Inland water environment Intermittent streams Invertebrates landscapes Local communities man‐made structure nestedness Network topologies River networks Rivers species diversity Strategic planning streams β‐diversity beta-diversity distance decays man-made structure drying invertebrates
ISSN:	0046-5070, 1365-2427
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Shrnutí:	Dispersal, defined as the movement of individuals among local communities in a landscape, is a central regional determinant of metacommunity dynamics in ecosystems. Whereas both natural and anthropogenic ecosystem fragmentations can limit dispersal, previous attempts to measure such limitations have faced considerable context dependency, due to a combination of spatial extent and associated environmental variability, the wide range of dispersal modes, and abilities of organisms or variation in network topologies. Therefore, the role dispersal plays compared to local environmental filtering in explaining metacommunity dynamics remains unclear in fragmented dendritic ecosystems. We quantified α‐ and β‐diversity components of invertebrate metacommunities across 10 fragmented headwater stream networks and tested the hypothesis that dispersal is the primary determinant of biodiversity organisation in these dynamic and spatially constrained ecosystems. Alpha‐diversity was much lower in intermittent than perennial reaches, even long after rewetting, indicating an overwhelming effect of drying including a legacy effect on local communities. Beta‐diversity was never correlated with environmental distances but predominantly explained by spatial distances accounting for river network fragmentation. The nestedness proportion of β‐diversity was considerable and reflected compositional differences where communities from intermittent reaches were subsets of perennial reaches. Altogether, these results indicate dispersal as the primary process shaping metacommunity dynamics in these 10 headwater stream networks, where local communities recurrently undergo extinction and recolonisation events. This challenges previous conceptual views that local environment filtering is the main driver of headwater stream metacommunities. As river networks become increasingly fragmented due to global change, our results suggest that some freshwater ecosystems currently driven by local environment filtering could gradually become dispersal‐limited. In this perspective, shifts from perennial to intermittent flow regimes represent ecological thresholds that should not be crossed to avoid jeopardising river biodiversity, functional integrity, and the ecosystem services they provide to society.
Bibliografie:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 content type line 23
ISSN:	0046-5070 1365-2427
DOI:	10.1111/fwb.13611