# Spatial coexistence of invasive ants in fragmented urban habitats of their native range

## TL;DR

This study explores how multiple invasive ant species coexist in fragmented urban habitats, revealing that their interactions depend on local conditions rather than fixed dominance.

## Contribution

The study provides a system-specific understanding of invasive ant coexistence in urban environments through context-dependent competitive interactions.

## Key findings

- Ant assemblages varied significantly among urban habitat patches in richness, diversity, and composition.
- No single invasive ant species consistently dominated across patches, indicating context-dependent interactions.
- Nylanderia fulva showed the highest numerical abundance and food discovery efficiency, while Solenopsis invicta was rare and subordinate.

## Abstract

Urban landscapes are increasingly recognized as key arenas for biological invasions, yet the mechanisms enabling the local coexistence of multiple highly invasive species remain poorly understood. Urban habitat fragmentation generates mosaics of habitat patches that differ in size, isolation, and microhabitat complexity, shaping ant community structure and competitive interactions.

Here, we investigated ant assemblages across a mosaic of urban habitat patches within a university campus in Buenos Aires, Argentina, focusing on four globally invasive ant species (Wasmannia auropunctata, Linepithema humile, Nylanderia fulva, and Solenopsis invicta) near the southern limit of their native ranges. We quantified species richness, abundance and composition using pitfall traps and evaluated species-specific indicators of food discovery, recruitment, and dominance using standardized bait experiments.

Ant assemblages differed significantly among habitat patches, with marked spatial variation in richness, diversity, and species composition. Contrary to expectations of rigid dominance hierarchies, no single species consistently dominated across patches. Nylanderia fulva showed the highest numerical abundance and discovery efficiency, L. humile exhibited the strongest recruitment ability, and W. auropunctata displayed localized dominance near nesting areas, while S. invicta was rare and competitively subordinate. Ordination and multivariate analyses indicated strong spatial structuring of assemblages, consistent with the influence of urban fragmentation and patch-level heterogeneity.

Overall, our results support a metacommunity perspective in which invasive ant coexistence in urban systems is mediated by context-dependent competitive interactions rather than fixed dominance hierarchies. By emphasizing the role of fine-scale spatial structure, this study provides a nuanced, system-specific contribution to understanding invasive ant dynamics in urban environments.