Intraspecific variation in the morphology of plants and their fruits nutritional content may play a major role in the selection of fruits and seed dispersal by animals. Birds make hierarchical decisions in the selection of both plant species and fruit they consume on an individual plant. This paper aims to test how the variation in the individual characteristics of Henriettea succosa (Melastomataceae) influence selection by frugivorous birds, and how this relationship is expressed in the mutualistic interaction networks. We conducted focal observations at 19 individual trees in the Reserva Biológica de Una, an area of Atlantic Forest in the brazilian state of Bahia. We performed 20 hours of focal observation for each individual tree, we measured canopy height, number of fruits they produce, fruits diameter as well as their concentration of sucrose, glucose and fructose. Moreover, we recorded birds behavior during fruits consumption. We built two interaction networks between birds and individuals of H. succosa. Firstly, we used interaction force values and secondly, we built a multilayer network using types of birds behavior while feeding on fruits. Based on these networks, we measured the centrality of each tree according to three metrics: degree, closeness and betweenness.
Results/Conclusions
Out of a total of 380 hours of focal observation we recorded 271 visits of birds belonging to 22 species and 8 families. The generalized additive model between centralities and individual trees parameters pointed out that evaluated centrality values reached peaks at shorter plants, largest fruits diameter and intermediate levels of sucrose. These fruit characteristics were selected by a great variety of bird species with different feeding habits and foraging at different vegetational layers. Our results suggest that bird selection of fruit and plant characteristics may affect both ecological and evolutionary processes. For instance, seed removal and dispersion relates to the rate of consumed fruits and bird selection of fruit and plant characteristics may influence next plant generations. Therefore, variation among different individual plants of the same population affects the selection of fruits by the bird community.