Structure and dynamics of an amphibian metacommunity in two regions.

1. The concept of metacommunity is based on the hypothesis that species occurrence depends on species dynamics and interactions on local and regional scales via the movements of individuals between localities. Metacommunity approaches are currently being applied to pond breeding taxa such as amphibians. 2. Given that animal movement is also influenced by the physical quality of the matrix to be crossed to reach a breeding habitat and by the affinity of the species for specific terrestrial habitats, matrix characteristics may enhance or hinder dispersal success. These characteristics would, in turn, affect the composition of larval assemblages at local level and, consequently, determine metacommunity structure and dynamics. 3. Here we compared the structures and dynamics of two metacommunities with the same pool of anurans along similar freshwater gradients in two regions that are well differentiated in terms of their respective terrestrial matrix. 4. Abundance of tadpole species and species assemblage in the two regions were determined principally by local processes (at pond level); however, the structure and dynamics of the communities differed. In one region species abundance was explained in part by landscape factors and consequently showed lower co-occurrence and lower colonization rates (species sorting models) indicating that terrestrial habitat could restrict animal movements, whereas in the other region higher co-occurrence and higher colonization rates (mass effect models) indicated low dispersal limitations.