Multiple environmental filters and competition affect the spatial co-occurrence of pond-breeding anurans at both local and landscape scales in the Brazilian Cerrado

Abstract

Environmental filtering and limiting similarity have both been hypothesized to influence patterns of species co-occurrence, but in contrasting ways. While environmental filtering results in a greater similarity of functional traits among co-occurring species, limiting similarity predicts that only species with different functional traits can co-occur. We evaluated the roles of environmental filtering versus competition in shaping patterns of species co-occurrence in terrestrial versus arboreal species of pond-breeding anurans, and also the influence of local and landscape environmental factors on those patterns, in the Brazilian Cerrado. We surveyed anurans within 85 ponds and adopted trait-based approaches to investigate patterns of co-occurrence within terrestrial and arboreal species groups. Local-scale environmental filters related to hydroperiod were more important than landscape factors. Habitat split was an important landscape filter, as was the amount of forest relative to pasture cover for arboreal species and the number of water bodies for terrestrial species. Habitat filtering was trait-mediated for arboreal species within ponds of similar size, hydroperiod, and degree of habitat split. Competition was weaker than environmental filters and led to a checkerboard distribution in arboreal species, whereas terrestrial species exhibited limiting similarity within small ponds. The processes that shape species co-occurrence patterns are dependent on spatial scale, degree of habitat degradation, and relative habitat use of species (terrestrial vs. arboreal), such that environmental changes as a result of land-use intensification have the potential to profoundly alter the structure and dynamics of pond-breeding anuran communities in the Cerrado.