Abstract
Within a metacommunity, both environmental and spatial processes regulate variation in local community structure. The strength of these processes may vary depending on species traits (e.g., dispersal mode) or the characteristics of the regions studied (e.g., spatial extent, environmental heterogeneity). We studied the metacommunity structuring of three groups of stream macroinvertebrates differing in their overland dispersal mode (passive dispersers with aquatic adults; passive dispersers with terrestrial adults; active dispersers with terrestrial adults). We predicted that environmental structuring should be more important for active dispersers, because of their better ability to track environmental variability, and that spatial structuring should be more important for species with aquatic adults, because of stronger dispersal limitation. We sampled a total of 70 stream riffle sites in three drainage basins. Environmental heterogeneity was unrelated to spatial extent among our study regions, allowing us to examine the effects of these two factors on metacommunity structuring. We used partial redundancy analysis and Moran's eigenvector maps based on overland and watercourse distances to study the relative importance of environmental control and spatial structuring. We found that, compared with environmental control, spatial structuring was generally negligible, and it did not vary according to our predictions. In general, active dispersers with terrestrial adults showed stronger environmental control than the two passively dispersing groups, suggesting that the species dispersing actively are better able to track environmental variability. There were no clear differences in the results based on watercourse and overland distances. The variability in metacommunity structuring among basins was not related to the differences in the environmental heterogeneity and spatial extent. Our study emphasized that (1) environmental control is prevailing in stream metacommunities, (2) dispersal mode may have an important effect on metacommunity structuring, and (3) some factors other than spatial extent or environmental heterogeneity contributed to the differences among the basins.
Highlights
The metacommunity concept has been increasingly applied when studying patterns of biodiversity
Ecology and Evolution published by John Wiley & Sons Ltd
We found some variability in the processes structuring metacommunities of the dispersal mode groups among the basins, which were evidenced by redundancy analysis (RDA), principal coordinate analysis (PCoA), PERMANOVA, and PERMDISP, this variability was not related to the differences in environmental heterogeneity and spatial extent of the regions
Summary
The metacommunity concept has been increasingly applied when studying patterns of biodiversity. This concept is based on the notion that both local-scale factors (e.g., local abiotic conditions and interspecific interactions) and large-scale factors (e.g., dispersal and regional climatic conditions) contribute to spatial variation in community structure (Leibold et al 2004; Holyoak et al 2005). In the seminal paper by Leibold et al (2004), four a 2013 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. Ecology and Evolution published by John Wiley & Sons Ltd
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