Dissimilarity of stream insect assemblages: effects of multiple scales and spatial distances
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PRIMARY RESEARCH PAPER
Dissimilarity of stream insect assemblages: effects of multiple scales and spatial distances Luiz Ubiratan Hepp • Adriano S. Melo
Received: 25 August 2011 / Revised: 27 September 2012 / Accepted: 22 October 2012 Ó Springer Science+Business Media Dordrecht 2012
Abstract In addition to the effects of environmental conditions, biotic assemblages may exhibit spatial structure depending on the scale of study. We tested whether the dissimilarity of stream insect assemblages is related to two types of spatial distances (stream corridor and overland distance), and evaluated the relative importance of diversity components at multiple spatial scales. Field data included assemblages of Ephemeroptera, Plecoptera, and Trichoptera found in 16 streams in four microbasins. We evaluated the relationship of the dissimilarity of assemblages with the distance types, using Mantel tests. In addition, we evaluated the relationships among the diversity components at multiple spatial scales, using additive
partitioning analysis. The biological dissimilarities were correlated only with the geographical distances. Additive partitioning showed that the values of richness observed in the b1 (among Surber), b2 (among riffles), b3 (among streams), and b4 (among microbasins) were higher than those expected. The highest variation of the richness was found in b3 (30.6%). We conclude that stream faunas are distributed in patches all over the studied spatial extent, causing a weak relationship of biological dissimilarity with distance but important beta components when compared to a completely homogenous distribution of the fauna. Keywords Additive partitioning Alpha diversity Beta diversity Dispersal Neotropical streams
Handling editor: Sonja Stendera L. U. Hepp A. S. Melo Programa de Po´s-Graduac¸a˜o em Ecologia, Universidade Federal do Rio Grande do Sul, Av. Bento Gonc¸alves 9500, CP 15007, Porto Alegre, RS CEP 91501-970, Brazil L. U. Hepp (&) Departamento de Cieˆncias Biolo´gicas, Universidade Regional Integrada do Alto Uruguai e das Misso˜es, Campus de Erechim, Av. Sete de Setembro, 1621, Erechim, RS CEP 99700-000, Brazil e-mail: [email protected] A. S. Melo Departamento de Ecologia, Instituto de Cieˆncias Biolo´gicas, Universidade Federal de Goia´s, CP 131, Goiaˆnia, GO CEP 74001-970, Brazil e-mail: [email protected]
Introduction Ecosystems have been studied as hierarchical systems, in which their constituting scales differ in dynamics, size, form, and successional stage (Wu & Loucks, 1995). These characteristics give ecosystems a high environmental heterogeneity on multiple spatial scales, which in turn should be reflected in their biological diversity. Small order streams are an important component of river networks (Clarke et al., 2008) and show a variety of habitats and environmental gradients, characterized by high spatial complexity (Allan, 2004). In a river
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Hydrobiologia
drainage basin, a hierarchical organization can be established from patches, to habitats, to stream segments, to micro
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