Positive Relation Between Abundance of Pericarpial Nectaries and Ant Richness in Tocoyena formosa (Rubiaceae)

Abstract

Ants can interact with plants in several ways, being one of the most common visitors of extrafloral nectaries (EFNs). However, pericarpial nectars (PNs) may represent to the ant community a similar resource as EFN would do. Here, we investigate how an ant community interacts with PNs by an individual-based network, using Tocoyena formosa as a model. We hypothesized that plants with more PN’s would present a higher ant richness in comparison to plants with less PNs and will occupy a central position in the network interaction. We observed 36 individuals of T. formosa in November of 2016. We recorded both the ant species and abundances on each plant, as well as the number of active PNs. To test our hypothesis, we performed a linear regression between PNs and ant richness. We performed a bipartite network analysis to obtain both the specialization and centrality metrics of each plant, and we also conducted linear regressions between the number of PNs and both the specialization and centrality. We confirmed our hypothesis, in which the ant community was more rich in individuals of T. formosa with more active PNs, and these individuals were more central, being important for the maintenance of the interactions with ants. We believe that coexistence between ants foraging is possible in T. formosa due to the seasonality and short time prevalence of the PNs, whose dominant ants do not have able time to master the resource and exclude the others, allowing different species to use the same plant.