PARENT SESSION
Oral Session 4: Biodiversity I: Communities and Function.
Presiding: C Holzapfel and D Ellsworth
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room B 110.
Meta-analysis of metacommunities.
Cottenie, Karl 1, 1 National Center for Ecological Analysis and Synthesis, UC Santa Barbara, Santa Barbara, CA
ABSTRACT- The relative influence of local environmental and regional, dispersal associated, variables on community structure is an important research topic in ecology. A new frame work uses the metacommunity concept to determine the importance of dispersal in community dynamics. A recent synthesis of metacommunity dynamics delineated two models of metacommunities that include environmental variability: species sorting and mass effect model. The main objective of this study was to 1) find empirical evidence for both models, 2) relate importance of dispersal to a) the spatial scale of the study, b) size of the organisms, c) habitat of the organisms. I collected 72 data sets with spatially explicit species and environmental data available. These data sets described a wide variety of habitats , taxonomic groups, and spatial scales. I decomposed the variation in the species composition data into variation explained by environmental, spatial, interaction between environmental and spatial, and both environmental and spatial variables following the procedure of Borcard et al. (1995). Environmental and spatial variables together explained on average 40 % of the species composition data. Pure environmental and spatial variables explained approximately 20 and 15 % respectively, indicating the presence of both species sorting and mass effect dynamics in these empirical metacommunities. Moreover, the relationship between the ratio of variance explained by pure environment on pure space and the spatial scale was significant, suggesting that increasing spatial scale will result in increased importance of species sorting due to a combined effect of more dispersal limitation and bigger environmental gradients. There were no effects of habit type or taxonomic groups on this relationship. These results both validate the importance and consolidate the theoretical concepts of metacommunity dynamics in real ecosystems.
Key words: meta-analysis, community structure, metacommunity dynamics, spatial scale