title: Metacommunity ecology meets biogeography: effects of geographical region, spatial dynamics and environmental filtering on community structure in aquatic organisms.
abstract: Metacommunity patterns and underlying processes in aquatic organisms have typically been studied within a drainage basin. We examined variation in the composition of six freshwater organismal groups across various drainage basins in Finland. We first modelled spatial structures within each drainage basin using Moran eigenvector maps. Second, we partitioned variation in community structure among three groups of predictors using constrained ordination: (1) local environmental variables, (2) spatial variables, and (3) dummy variable drainage basin identity. Third, we examined turnover and nestedness components of multiple-site beta diversity, and tested the best fit patterns of our datasets using the "elements of metacommunity structure" analysis. Our results showed that basin identity and local environmental variables were significant predictors of community structure, whereas within-basin spatial effects were typically negligible. In half of the organismal groups (diatoms, bryophytes, zooplankton), basin identity was a slightly better predictor of community structure than local environmental variables, whereas the opposite was true for the remaining three organismal groups (insects, macrophytes, fish). Both pure basin and local environmental fractions were, however, significant after accounting for the effects of the other predictor variable sets. All organismal groups exhibited high levels of beta diversity, which was mostly attributable to the turnover component. Our results showed consistent Clementsian-type metacommunity structures, suggesting that subgroups of species responded similarly to environmental factors or drainage basin limits. We conclude that aquatic communities across large scales are mostly determined by environmental and basin effects, which leads to high beta diversity and prevalence of Clementsian community types.
authors.affiliation: Natural Environment Centre, Biodiversity, Finnish Environment Institute, Paavo Havaksen Tie 3, P.O. Box 413, 90014, Oulu, Finland. jani.heino@environment.fi.
authors.forename: Jani
authors.initials: J
authors.lastname: Heino
authors.affiliation: Department of Geosciences and Geography, University of Helsinki, P.O. Box 64, 00014, Helsinki, Finland.
authors.forename: Janne
authors.initials: J
authors.lastname: Soininen
authors.affiliation: Geography Research Unit, University of Oulu, P.O. Box 3000, 90014, Oulu, Finland.|Freshwater Centre, State of Surface Waters, Finnish Environment Institute, P.O. Box 413, 90014, Oulu, Finland.
authors.forename: Janne
authors.initials: J
authors.lastname: Alahuhta
authors.affiliation: Department of Environmental Sciences, University of Helsinki, P.O. Box 65, 00014, Helsinki, Finland.
authors.forename: Jyrki
authors.initials: J
authors.lastname: Lappalainen
authors.affiliation: Department of Physiological Diversity, Helmholtz Center for Environmental Research, UFZ, Permoserstr. 15, 04318, Leipzig, Germany.|German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103, Leipzig, Germany.|Department of Ecology, University of Oulu, P.O. Box 3000, 90014, Oulu, Finland.
authors.forename: Risto
authors.initials: R
authors.lastname: Virtanen
mesh_terms: D000818:Animals; D059001:Aquatic Organisms; D004463:Ecology; D017753:Ecosystem; D004777:Environment; D015048:Zooplankton
keywords: Bryophytes; Diatoms; Fish; Invertebrates; Lakes; Macrophytes; Metacommunities; Streams