Mineral substrates as evolutionary drivers of soil microbial diversity through the rare biosphere

Even under nutrient-rich conditions, non-nutritive and chemically inert minerals, exemplified by quartz, actively reshape microbial community assembly. Through controlled serial-passage experiments, we show that distinct substrates selectively enrich rare biosphere members that expand functional potential and seed adaptation, while dominant taxa sustain core processes. These results reveal that mineral surface properties and physical interfaces, rather than nutrient supply, govern microbial diversification and evolutionary trajectories. Accordingly, the mineralosphere emerges as a dynamic microhabitat where abiotic complexity regulates biodiversity, metabolism, and long-term community succession. This reframes minerals and rocks as active ecological and evolutionary agents, bridging geomicrobiology and evolutionary ecology, with implications for soil health, biogeochemical cycling, and the origin and maintenance of microbial diversity.