Fine spatial grain, large spatial extent and biogeography of macrophyte‐associated cladoceran communities across Neotropical floodplains

• Published in: Freshwater biology Vol. 62; no. 3; pp. 559 - 569
• Main Authors: Rocha, Mariana P., Heino, Jani, Machado‐Velho, Luiz F., Lansac‐Tôha, Fernando M., Lansac‐Tôha, Fábio A.
• Format: Journal Article
• Language: English
• Published: Oxford Wiley Subscription Services, Inc 01-03-2017
• Subjects: beta diversity; Brazil; Cladocera; Freshwater; spatial dynamics; species sorting; variation partitioning
• ISSN: 0046-5070; 1365-2427
• DOI: 10.1111/fwb.12885

Summary
Metacommunity structure may be strongly influenced by spatial dynamics and environmental factors, as well as biogeographic effects. Here, we examined variation in lake cladoceran communities associated with floating macrophytes in the four major Brazilian floodplain systems (Amazônia, Araguaia, Pantanal and Paraná) in relation to local environmental factors, spatial components, climate variables and basin identity.
Moran's eigenvector maps were used as a proxy to examine spatial structures within each drainage basin. The final sets of local environmental, climate and spatial variables were selected for constrained ordination models, using a forward selection method. We used variation partitioning to decompose variation in cladoceran community composition in relation to the four sets of predictor variables. Beta‐diversity indices were calculated to quantify the contributions of turnover and nestedness components to total beta diversity of cladocerans within each basin and across the basins.
Variation partitioning showed that the pure fractions were relatively small, ranging from around zero for spatial and basin identity variables to 2% for climate variables and 4% for local environmental variables. The shared effect of local environmental, climate and basin identity was considerable, accounting for 17% of the total variance. Furthermore, the shared effect of climate and basin identity was also considerable (6%). In total, 32% of variation in cladoceran community structure could be explained by our predictor variables. Cladoceran metacommunities showed high levels of beta diversity attributed to the turnover component, within each floodplain and across all four floodplains.
Our finding showed that species sorting was likely to be the main agent structuring cladoceran communities. Spatial processes were not important at very large spatial scales, contrary to what has been found in previous studies. This finding was most likely due to the inclusion of climatic variables in our analysis, combined with the high dispersal ability of cladocerans.