Structure and trophic interactions in anuran metacommunities in Midwestern Brazil

Abstract

Communities and metacommunities vary in composition over time and space. Likewise, species interactions can also vary along these dimensions. In this way, my objective in this thesis is to understand the effects of time and space in anuran metacommunities as well as in anuran-prey interactions. In the first chapter, I analyzed the structural patterns in anuran–prey antagonistic interaction networks in different parts of the world. I suggest that different processes, mediated mainly by latitude, are shaping the architecture of anuran–prey networks across the globe. In the second chapter, I examined anuran seasonal patterns of local contributions to beta diversity (LCBD) in different ecoregions of Western Brazil, and assessed their correlation with species richness and if environmental and/or spatial predictors would drive patterns of LCBD. I found that LCBD patterns were similar between seasons with sites tending to contribute in the same way for community composition uniqueness during the dry and rainy seasons. Among studied ecoregions, Cerrado showed higher LCBD values in both seasons. In addition, LCBD was negatively correlated with species richness in the dry season. We also found that LCBD variation was explained by ecoregion in the dry season, but in the rainy season, both environmental and spatial global models were non-significant. Finally, in the third chapter, I assessed the turnover of anuran-prey interactions between seasons and among four ecoregions in western Brazil. My results indicated that the variation in interaction beta diversity between seasons and among areas was generated by differences in prey availability. Interaction turnover between ecoregions and seasons was high and driven primarily by interaction rewiring. In addition, the beta diversity of species was positively related to geographical distance, but not to interaction beta diversity. I propose that fluctuations in prey abundance along with limited dispersal abilities of anurans and their prey are responsible for the temporal and spatial pattern that emerged in my anuran-prey metaweb. Thus, anuran metacommunities and interactions vary in time and space but the processes that are driving these patterns are unique and differ depending on the ecoregion.