Ant Diversity of the Xisha Islands: Community Structure, Exotic Species Colonization, and Ecological Functions in a Tropical Coral Archipelago

ABSTRACT The Xisha Islands in the South China Sea are a typical tropical coral archipelago at the forefront of global climate change and anthropogenic disturbance, yet their ant diversity and ecological functions remain uncharacterized. In this study, we systematically surveyed ants across seven islands, integrating morphological identification with molecular species delimitation (based on COI barcodes, with ABGD, ASAP, and bPTP methods) to compile the species inventory, and analyzed the effects of island geographic traits, anthropogenic disturbance, and vegetation type on ant communities. We recorded 21 species from 17 genera and 5 subfamilies, comprising 70% native and 30% exotic species. Species richness showed marginally nonsignificant positive correlations with island area and the nearest neighbor distance, whereas anthropogenic disturbance emerged as the key driver of exotic ant colonization. No environmental factors significantly explained community composition. Most species were ground‐dwelling omnivores; 75% formed mutualisms with hemipterans, and some exhibited potential pollination and seed dispersal functions. This first comprehensive ant inventory for the Xisha Islands fills a critical knowledge gap in the South China Sea myrmecofauna and provides a scientific baseline for biodiversity conservation and invasive species management in coral island ecosystems.