A influência das características funcionais nas propriedades estruturais das redes de interações entre abelhas e plantas e na especialização das espécies

Abstract

Interaction networks are regulated by several factors, including functional traits, which one can predict network structural properties and also define the interaction partners pairs. The present study aims to evaluate the influence of functional traits on the structural properties of plant-bee networks and species specialization in forest areas of the eastern Amazon. Interaction data were collected at 14 sampling sites in the Carajás National Forest (Pará; Amazon biome). We used the metrics Interaction Diversity (ID) and Interaction Evenness (IE) to describe the network topological structure. The specialization metric d' was used to determine whether species were generalists or specialists. The functional diversity was represented by the following metrics: Functional Dispersion (FDis) and Functional Evenness (FEve). Z-score analyses were performed to assess whether there were differences in the ID and IE metrics considering the 14 networks analyzed. To assess whether and which bee and plant functional traits are associated with specialization, we used linear models for numerical traits and ANOVA for categorical traits. For the assessment of the relationship between ID and IE with functional diversity, we made a selection of linear models corrected for network size, with network metrics as response variables and functional metrics as predictors. We recorded a total of 60 bee species visiting 74 plant species. Our results showed that there was no significant difference in the ID and IE metrics between the sampling sites. This indicates that the diversity and evenness of interactions did not vary between sampling sites. The species Borreria ocymifolia (Roem. & Schult.) Bacigalupo & E.L.Cabral has on average low values of specialization d'. It is also the most common plant, occurring in 11 of the 14 sampled sites. Another six more common plant species that were identified also have on average low values of specialization d', which may be an indication of opportunistic partner selection in comparison to other species in the networks. The species Trigona guianae Cockerell, 1910 has an average value of specialization d'. It is also the most common bee, occurring at all sampled sites. Functional traits were not related to the specialization d' of either plants or bees. Functional dispersal of plants was positively related to interaction diversity in this study, suggesting that plant communities are functionally more unique. Network size was also positively related to interaction diversity. In conclusion, it is important to consider the diversity and species functions of bee-plant interaction networks to understand the ecology of these relationships.