Ecological specificity explains infection parameters of anuran parasites at different scales

Understanding the determinants of parasite infection in different hosts is one of the main goals of disease ecology. Evaluating the relationship between parasite–host specificity and infection parameters within host communities and populations may contribute to this understanding. Here we propose two measures of specificity that encompasses phylogenetic and ecological relatedness among hosts and investigated how such metrics explain parasite infection prevalence and mean infection intensity (MII). We analysed the parasites associated with an anuran community in an area of Atlantic Forest and used the number of infected hosts and the net relatedness index to calculate the phylogenetic and ecological specificities of the parasites. These specificity measures were related to infection metrics (prevalence and MII) with generalized linear mixed models at community (all hosts) and population (infected host species) scales. Parasite prevalence was correlated with the number of infected hosts and, when considering only multi-host parasites, was positively related to parasite ecological specificity at community and population scales. Thus, parasite species have similar prevalences in ecologically closer hosts. No relationship was found for parasite MII. Incorporating ecological characteristics of hosts in parasite specificity analyses improves the detection of patterns of specificity across scales.

The roles of anurans in antagonistic networks are explained by life-habit and body-size

Interactions among living beings are the structuring basis of ecosystems, and studies of networks allow us to identify the patterns and consistency of such interactions. Antagonistic networks reflect the energy flow of communities, and identifying network structure and the biological aspects that influence its stability is crucial to understanding ecosystem functioning. We used antagonistic anuran interactions-predator-prey and host-parasite-to assess structural patterns and to identify the key anuran species structuring these networks. We tested whether anuran body-size and life-habit are related to their roles in these networks. We collected individuals of 9 species of anurans from an area of the Atlantic Forest in Brazil and identified their prey and helminth parasites. We used network (modularity, specialization, and nestedness) and centrality metrics (degree, closeness, and betweenness) to identify the role of anuran species in both networks. We then evaluated whether anuran body-size or life-habit were related to anuran centrality using generalized linear mixed models. The networks formed specialized interactions in compartments composed by key species from different habits. In our networks, anurans with rheophilic and cryptozoic habit are central in predator-prey networks, and those with larger body size and arboreal and cryptozoic habit in the host-parasite network. This study represents a step towards a better understanding of the influential factors that affect the structure of anuran antagonist networks, as well as to recognize the functioning roles of anuran species.

Anuran's habitat use drives the functional diversity of nematode parasite communities

Understanding the processes responsible for structuring communities has been a challenge in ecology, and parasite communities are an excellent system to address this issue. The use of different diversity metrics can help us to understand the determinants of the structure of parasite communities, and in this sense, functional diversity indexes make it possible to measure the variability of organism traits in communities. In this study, we investigate how host body size and habitat use influence the functional diversity of nematode parasite infracommunities. We collected and examined 213 individuals of 11 species of anurans in an area of the Brazilian Atlantic Forest, calculated Rao's quadratic entropy as a measure of functional diversity of parasite infracommunities, and tested if this index was related to host body size and habitat use with an analysis of covariance (ANCOVA). Anuran species varied in body size (from 1.80 to 10.35 cm) and habit use (arboreal, terrestrial, and semiaquatic), and in the functional diversity of parasite infracommunities (Rao's quadratic entropy ranged from 0 to 0.196). We observed that anurans with larger body size and terrestrial habit showed significantly greater functional diversity of parasites. We conclude that anuran characteristics drive the functional diversity of nematode parasite communities, and highlight the importance of using different diversity metrics to understand the determinants in the host-parasite interaction.