Disturbance-driven trait shifts in croplands alter the trophic structure of tropical ant assemblages.

Understanding how croplands can support food production while maintaining ecosystems functionality is a major challenge in the Anthropocene. This requires a functional approach to understand how different farming systems reshape species occurrence and functional roles, and how they affect species trophic structure in human-modified ecosystems. We investigated how different cropland types influence trait selection, trophic position, and food chain length of ant assemblages in a tropical region severely threatened by agricultural expansion. We used ants as a model group because of their sensitivity to environmental changes and functional diverse. Samples occurred in 22 sites in the Brazilian Cerrado, encompassing different cropland types (large-scale soybean monocultures, pastures and organic farms) and three natural vegetation types (grasslands, savannas, and forests). Species were assigned to functional groups, and stable isotope analysis (δ13C, δ15N) was used to assess niche shifts, trophic structure, and food web length across habitat types. Intensive agriculture, particularly soybean crops, reduced taxonomic diversity, favored generalist species, and affected the occurrence of traits related to body size, foraging behavior, and sensory capacity. These changes altered food chains and homogenized functional roles compared to natural habitats. Organic farming showed intermediate impacts, mitigating some biodiversity and functional losses. Natural habitats complemented each other in maintaining broader trophic roles and high functional diversity. Resource availability and disturbance intensity jointly drive trait-based selection, shaping the trophic structure of ant assemblages. Agricultural intensification simplifies ant-mediated ecosystem functions, while diversified farming practices and the preservation of native vegetation can buffer against biotic homogenization and maintain ecological complexity.