Living in a changing world: effects of roads and Pinus monocultures on an anuran metacommunity in southern Brazil

Abstract

Amphibians are undergoing global-scale declines due to the increased incidence of anthropogenic stressors. The loss of species with unique evolutionary histories and functional traits poses a serious risk to the maintenance of ecosystem functions in aquatic environments, already directly affected by several anthropogenic land-use changes. Here, we investigated the influence of anthropogenic stressors (roads and Pinus monocultures) on functional, phylogenetic and taxonomic composition and functional dispersion of an anuran metacommunity of 33 ponds in southern Brazil. We expected for the relative influence of anthropogenic stressors to vary according to the compositional facet, with a greater influence of these stressors on the functional and phylogenetic than on the taxonomic facet. We also expected traits related to habitat exploration (head shape and eye size and position) to be more influenced by Pinus monocultures, while the traits related to the dispersion and the physiological control of individuals (limb length and body mass) to be similarly influenced by roads and Pinus. To evaluate this, we used PERMANOVA analyses for each of the compositional facets and anthropogenic stressor, and path models to verify all possible relationships between patterns of functional dispersion and anthropogenic stressors. We found that, while the distance from ponds to Pinus monocultures influences the phylogenetic composition, distance to roads influences the functional composition; distance to roads affects mostly the functional dispersion of the communities. These anthropogenic stressors affect the structure of anuran communities, even those formed by generalist species in terms of habitat use. There is a decline in diversity in communities located close to Pinus and roads, leading to losses in the evolutionary history accumulated in these communities. The control of vehicle traffic during reproduction periods and the maintenance of areas with natural vegetation, particularly around ponds, may help mitigate the negative effects of anthropogenic stressors on anuran communities.