Biological drivers of individual-based anuran-parasite networks under contrasting environmental conditions.

Understanding the mechanisms driving host-parasite interactions has important ecological and epidemiological implications. Traditionally, most studies dealing with host-parasite interaction networks have focused on species relationship patterns, and intra-population variation in such networks has been widely overlooked. In this study, we tested whether the composition of parasite communities of five anuran species (Leptodactylus chaquensis, Leptodactylus fuscus, Leptodactylus podicipinus, Pseudis paradoxa and Pithecopus azureus) vary across a pasture pond and a natural reserve site in south-eastern Pantanal, Brazil. We analysed the structure of individual-based networks of these five anuran species, assessed the species roles in the networks and the contribution of host species and body size to interaction strength in the networks, and tested if network ecological attributes varied between the two sites. We observed a total of 17 parasite morphospecies in 151 individual anurans and found that the abundance of parasite species tends to vary, with host species being the main filter driving parasite community structure. The composition of core parasite species remained similar between study sites, and network structure (i.e. parasite richness, interaction diversity, specialization, nestedness and modularity) did not change between pasture and natural reserve. Individual traits of hosts influenced network descriptors since larger hosts presented greater interaction strength independent of the study site. In short, we found that the occurrence of highly connected parasite taxa in both the pasture and the reserve sites may have promoted similarity in network structures, and host body size was the best predictor of associations with parasites in both study sites.