Biodiversity and Conservation

, 18:3909

Richness gradients of stream invertebrates across the USA: taxonomy- and trait-based approaches

Original Paper

DOI: 10.1007/s10531-009-9688-1

Cite this article as:
Bêche, L.A. & Statzner, B. Biodivers Conserv (2009) 18: 3909. doi:10.1007/s10531-009-9688-1


Large-scale diversity patterns in relationship to environmental factors at multiple spatial scales have been well-studied for many taxonomic groups; however, freshwater ecosystems remain understudied. Biodiversity is now widely recognized to encompass many more factors than just species numbers, particularly the inclusion of functional attributes. In this study, we examined richness patterns of stream invertebrate genera and their biological traits (“functional” richness) across 364 sites in the contiguous USA. In particular, we focused on the relationship between taxonomy- and trait-based richness to test for functional redundancy in stream communities. Further, we obtained environmental data to model the relative importance of local and watershed-scale environmental factors and residual spatial (latitude, longitude) influences on taxonomy- and trait-based richness. Trait richness increased linearly with genus richness (slope ≪ 1), although this appears to be an artifact of the restricted range of genus richness in our study (32 genera maximum). Furthermore, trait richness was significantly lower than expected under random community assembly. In contrast, the Ephemeroptera, Plecoptera, and Trichoptera (EPT) genera exhibited a saturating pattern between trait and genus richness and trait richness was no different from random. Our study indicates that there is functional redundancy among stream invertebrate genera, likely as a result of harsh habitat filters limiting trait diversity. Environmental factors (including spatially structured environmental factors) were always more important than spatial factors (latitude, longitude) in structuring richness despite strong longitudinal patterns of all richness measures (these differences were only significant for EPT genera). Finally, we found no significant difference in the relative importance of local and watershed scale environmental factors for taxonomy- and trait-based richness.


Diversity–function relationship Environmental filtering Functional diversity Land-use Redundancy Variance partitioning 



Aikake’s Information Criterion


Environmental Monitoring and Assessment Program


US Environmental Protection Agency


Ephemeroptera, Plectopera, Trichoptera


Geographic Information System


Standard deviation


Standard error


United States of America


Water Survey of America

Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  1. 1.CNRS-UMR 5023 Écologie des Hydrosystèmes FluviauxUniversité de LyonVilleurbanne CedexFrance
  2. 2.CNRS—Biodiversité des Écosystemes LotiquesParcieuxFrance

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