Interaction frequency dataset of an EFN-mediated ant–plant network in a seasonally dry tropical forest (Caatinga, Brazil)

This dataset contains the quantitative interaction frequencies between ant species and extrafloral nectary (EFN)-bearing plant species recorded in a seasonally dry tropical forest (Caatinga) in northeastern Brazil. The data were collected over 12 non-consecutive months (seven months in 2021 and five months in 2022), encompassing three daily observation periods to capture variation in ant activity across the diel cycle. Interactions were defined as instances in which an ant’s mouthparts contacted an EFN. The dataset includes only recurrent interactions; one-time interactions (singletons) were excluded to reduce noise and focus on consistent interaction patterns. Each row represents an ant species and each column represents an EFN-bearing plant species, with cell values indicating the total frequency of observed interactions across the entire sampling period. The dataset supports analyses of ecological network structure, species roles, interaction specialisation, and trait–network relationships in facultative mutualisms. It was used to calculate network-level metrics (e.g., connectance, specialisation H2′, interaction evenness) and species-level metrics (e.g., d′, degree, interaction strength). Morphological trait data for ants and plants are available in the Supplementary Materials of the associated publication. This dataset contributes to understanding how functional traits relate to network structure without constraining partner identity in diffuse, facultative ant–plant mutualisms.