Spatial and phylogenetic structure drive frugivory in Tyrannidae birds across the range of Brazilian Araucaria forests

We aimed to verify if frugivory in Tyrannidae birds (tyrants flycatchers) is influenced by environmental conditions, spatial filters, phylogenetic structure and food availability in Brazilian Araucaria forests. We used range maps to describe Tyrannidae species composition of 33 cells (0.25 degrees x 0.25 degrees) distributed along the Araucaria forest distribution range. Araucaria forests occur in southern and southeastern Brazil and northeastern Argentina, from 30 degrees S to 20 degrees S and at elevations above 500 m a.s.l. We compiled the feeding habits of each species from literature to calculate the proportion of frugivorous Tyrannidae in each cell. After that, we evaluated separately the influence of environmental descriptors, spatial filters (PCNM), phylogenetic structure (PCPS) and resource availability (proportion of zoochorous species) on the proportion of frugivorous birds using model selection based on AIC. Then we built a path model to evaluate the direct and indirect influences of different set of variables on frugivory. The path model showed that phylogenetic structure and spatial filters were the main factors determining the variation in frugivory in Araucaria forest sites. The environmental variable had no direct effect on frugivory, but presented an indirect effect via phylogenetic structure. Furthermore, zoochory was not selected as an important variable determining any other and was not included in the model. Our results showed that the influence of environment on frugivory by Tyrannidae birds was indirect via spatial and phylogenetic structure, that zoochory was not an important factor determining frugivory and that phylogenetic niche conservatism in feeding habits plays a role in determining the structure of Tyrannidae bird communities in Brazilian Araucaria forests.