What and When Local Predictors Drive Tadpole Diversity in Subtropical Temporary Ponds?

Abstract

We evaluated seasonal variation in taxonomic, functional and phylogenetic diversity and redundancy of tadpoles in 401 points of 10 ponds in southern Brazil. We predicted i) congruent patterns between all components of diversity and environmental descriptors; ii) stronger effects of environment in the diversity components in seasons when the water level in ponds is low; iii) diversity components to be influenced by distinct sets of environmental factors in different periods. Predictions were tested using Linear Mixed Models. We observed positive influence of water depth on taxonomic, functional and phylogenetic diversity, as well as on functional redundancy during periods when the water level in ponds is high. Phylogenetic redundancy was not explained by any of the selected environmental variables. When the water level in ponds is low none of the environmental descriptors affects any of the diversity components. Environmental filtering seems to strongly influence tadpole community structure in temporary ponds, at least in periods when water depth gradients create a variety of micro-habitats allowing diverse sets of species to settle and co-occur. These species sets are then filtered according to their swimming and foraging abilities along the depth gradient, where intermediate depths should contain the greatest tadpole diversity.