Deciphering the rhizosphere microbial and faunal diversity and ecological interactions of Rubus niveus: The top invasive plant threat in Galápagos

Invasive plant species represent a serious threat to native plants and fauna, particularly on isolated islands such as the Galápagos Archipelago (Ecuador). Here, we characterised rhizosphere communities associated with the invasive Rubus niveus (blackberry) across contrasting habitats. We sampled the rhizosphere of R. niveus at three locations on Santa Cruz Island (Galápagos) that differ in climate, vegetation, and edaphic conditions. We characterised rhizosphere chemical properties and used environmental DNA metabarcoding to profile bacterial, fungal, and soil faunal communities. Chemical characteristics of the rhizosphere differed significantly among sites, along with the bacterial, fungal, and faunal communities. Biomarker analysis identified distinct taxa associated with each site (52 site-specific taxa), indicating strong habitat-driven differentiation. Co-occurrence networks showed site-specific ecological associations, with only 2 of 3,266 associations shared across all three networks. Despite this site-specificity, a shared core rhizobiome, comprising bacteria, fungi, and soil fauna, was consistently associated with R. niveus across all three habitats. These taxa may contribute to nutrient cycling, pathogen suppression, and pollination. Together, these results suggest that despite the differences, R. niveus can integrate effectively into novel habitats while maintaining a conserved core rhizobiome. This strategy may help explain the ecological success of R. niveus across contrasting habitats and highlights the importance of considering below-ground soil–plant interactions in studies of biological invasions.