Differences in environmental heterogeneity promote the nestedness of Chironomidae metacommunity in Neotropical floodplain lakes

Diferenças na heterogeneidade ambiental promove o aninhamento da metacomunidade de Chironomidae em lagoas de inundação neotropicais

Abstract

Aim: Gradients of environmental heterogeneity perform a strong influence on the distribution of organisms and determine differences in composition, where more physically complex habitats harbor greater species richness than those simpler. We took as assumptions that differences in environmental requirements of taxa promote distinct distribution patterns which are carried through to community nestedness. Therefore, we hypothesized that more heterogeneous sites hold more nested, richer and abundant communities than those less heterogeneous ones.

Methods

We analyzed Chironomidae occurrence of 29 floodplain lakes, through one-year-surveys. Analyses of variance were performed to test differences among data. To test our hypothesis, we calculated correlations between the gradients of environmental heterogeneity and Chironomidae metacommunity.

Results

Highest values in all Chironomidae attributes were recorded in general to the floodplain lakes from Paraná System, mainly in September. Positive correlation between all Chironomidae attributes (i.e, richness, density, Biodiversity score and NODF index) both with PCA scores and variation coefficient values supported our initial hypothesis about the importance of environmental heterogeneity in metacommunity assembly.

Conclusions

We have demonstrated how differences in environmental heterogeneity promote the nestedness in floodplain lakes and the importance of more heterogeneous places in supporting richer and more abundant communities in species. Such results contribute to future studies on composition and richness of Chironomidae community in other kind of environments. Nested distribution suggests that, despite the existence of floodplain lakes including most of the Chironomidae richness, considering the dispersal ability of species and environmental requirements, there is a strong interaction between all environments of the area. Therefore, areas that have locations with different patterns of richness and composition are critical to maintaining the diversity of the group at the landscape level.

Keywords:
biodiversity; distribution models; floodplain; dispersion; richness