Padrões ecológicos e funcionais em diferentes tipos de interações mutualistas formiga-planta na Amazônia Brasileira

Abstract

Ant-plant mutualistic interactions are central components of the structure and functioning of tropical communities. These associations vary in specialization and frequency, ranging from generalized interactions mediated by food rewards (e.g., extrafloral nectaries) to highly specialized mutualisms, involving ant nesting in myrmecophytic plants. However, the ecological and functional drivers structuring these interactions across environmental contexts remain poorly understood. In this thesis, we investigated how environmental filtering in seasonally flooded forests and ant functional traits shape ant-plant interaction patterns in the Brazilian Amazon using ecological network and functional traits approaches. In Chapter 1, we evaluated how variation in habitat conditions between igapó forests and terra-firme forests affects the structure of ant-plant interaction networks. We tested the hypothesis that the instability of seasonally flooded forests acts as an environmental filter on ant assemblages, resulting in changes in species composition and in the architecture of interaction networks. Networks in terra-firme forests exhibited higher interaction diversity, whereas igapó forests showed higher interaction specialization. In Chapter 2, we used a comprehensive dataset of arboreal ant species from the Brazilian Amazon to test whether species associated with myrmecophytic plants and plants with extrafloral nectaries exhibit functional convergence in morphological traits related to locomotion and feeding. We use multivariate analyses and functional hypervolumes and hypothesize that more specialized mutualisms (ant-myrmecophyte associations) are linked to a narrower trait set. Results revealed strong functional convergence, particularly in locomotion traits, among ants associated with myrmecophytes, whereas extrafloral-nectary associations involved greater functional diversity. Together, these findings show that environmental filtering and mutualist specialization act complementarily in organizing ant-plant interactions in the Amazon. This thesis provides an integrated understanding of how ecological and functional processes shape tropical mutualisms, with implications for community ecology and for predicting responses to environmental change in Amazonian forests.