Metagenomic and amplicon sequencing uncover adaptation and sympatric coexistence of the alien snail Rumina decollata (Linnaeus, 1758) (Stylommatophora, Achatinidae) with native terrestrial snails in East China

Alien species expand beyond their native ranges by withstanding ecological stress and exploiting diverse resources, yet the potential contribution of the microbiome to ecological persistence in novel environments remains poorly understood. The Mediterranean snail Rumina decollata is classified as invasive in numerous foreign regions while being merely regarded as an alien species in China, where it coexists sympatrically with native Acusta ravida and Euphaedusa aculus snails across eastern China. Gut microbial samples of R. decollata were collected from urban residential quarters, a university campus, and a mountain park in Nanjing for metagenomic sequencing, and 16S rRNA and ITS amplicon sequencing were conducted on the three snail species and surrounding soils. Conserved microbial pathways suggest broad metabolic potential for diverse dietary resources. Chitin related pathways were enriched in mountain populations, while xenobiotic degradation pathways were more represented in urban individuals, indicating habitat associated functional variation. Amplicon data demonstrated that gut microbiota were distinctly separated from soil communities, indicating clear host-associated differentiation. The gut microbiome of R. decollata was more similar to that of A. ravida , potentially reflecting similarities in plant resource use. Collectively, host-associated gut microbiota differentiation and habitat-dependent functional variation are consistent with potential ecological differentiation and provide insights into the microbiome associated with the coexistence of these snail species.