title: A comparative analysis of metacommunity types in the freshwater realm.
abstract: Most metacommunity studies have taken a direct mechanistic approach, aiming to model the effects of local and regional processes on local communities within a metacommunity. An alternative approach is to focus on emergent patterns at the metacommunity level through applying the elements of metacommunity structure (EMS; Oikos, 97, 2002, 237) analysis. The EMS approach has very rarely been applied in the context of a comparative analysis of metacommunity types of main microbial, plant, and animal groups. Furthermore, to our knowledge, no study has associated metacommunity types with their potential ecological correlates in the freshwater realm. We assembled data for 45 freshwater metacommunities, incorporating biologically highly disparate organismal groups (i.e., bacteria, algae, macrophytes, invertebrates, and fish). We first examined ecological correlates (e.g., matrix properties, beta diversity, and average characteristics of a metacommunity, including body size, trophic group, ecosystem type, life form, and dispersal mode) of the three elements of metacommunity structure (i.e., coherence, turnover, and boundary clumping). Second, based on those three elements, we determined which metacommunity types prevailed in freshwater systems and which ecological correlates best discriminated among the observed metacommunity types. We found that the three elements of metacommunity structure were not strongly related to the ecological correlates, except that turnover was positively related to beta diversity. We observed six metacommunity types. The most common were Clementsian and quasi-nested metacommunity types, whereas Random, quasi-Clementsian, Gleasonian, and quasi-Gleasonian types were less common. These six metacommunity types were best discriminated by beta diversity and the first axis of metacommunity ecological traits, ranging from metacommunities of producer organisms occurring in streams to those of large predatory organisms occurring in lakes. Our results showed that focusing on the emergent properties of multiple metacommunities provides information additional to that obtained in studies examining variation in local community structure within a metacommunity.
authors.affiliation: Biodiversity, Finnish Environment Institute, Natural Environment Centre P.O. Box 413, FI-90014, Oulu, Finland.
authors.forename: Jani
authors.initials: J
authors.lastname: Heino
authors.affiliation: Department of Geosciences and Geography, University of Helsinki P.O. Box 64, FI-00014, Helsinki, Finland.
authors.forename: Janne
authors.initials: J
authors.lastname: Soininen
authors.affiliation: Department of Geography, University of Oulu P.O. Box 3000, FI-90014, Oulu, Finland ; Finnish Environment Institute, Freshwater Centre, State of Surface Waters P.O. Box 413, FI-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, FI-00014, Helsinki, Finland.
authors.forename: Jyrki
authors.initials: J
authors.lastname: Lappalainen
authors.affiliation: Department of Biology, University of Oulu, Botanical Museum P.O. Box 3000, FI-90014, Oulu, Finland.
authors.forename: Risto
authors.initials: R
authors.lastname: Virtanen
keywords: Algae; invertebrates; lakes; macrophytes; metacommunity; multigroup analysis; streams