Habitat-shaped microbial life-history strategies and host niche specialization govern soil ARG transfer potential

Antibiotic resistance genes (ARGs) have been extensively studied in terms of their environmental sources and anthropogenic drivers. However, the ecological mechanisms by which soil microbiomes mediate ARG persistence and transfer remain poorly understood, even though microorganisms are the primary hosts, vectors, and regulators of resistance traits. We compared alpine plateaus and lowland plains, two habitats with contrasting ecological and anthropogenic conditions, to investigate how habitat-driven microbiome processes affect ARG transmission. We found that plateau soils harbored lower ARG abundance (6.2%∼86.3%) and reduced horizontal transfer capacity (94.12%) compared to plain soils. This difference was primarily driven by distinct microbial traits shaped by habitat differences. Plateau microbiomes were dominated by k-strategist taxa characterized by slower growth rates and reduced connectivity in co-occurrence networks, thereby limiting opportunities for ARG exchange. In addition, ARG-carrying hosts in plateau soils exhibited broader ecological niches and a higher proportion of generalist taxa (48.2%), which exerted stronger negative interactions on specialists, thereby constraining the spread of resistance traits. These findings highlight how habitat-shaped microbial traits restrict ARG transmission and offer new insights into the ecological containment of antibiotic resistance in agroecosystems.