Soil biota and chemical interactions promote co-existence in co-evolved grassland communities

1. Plant populations can exhibit local adaptation to their abiotic environment, such as climate and soil properties, as well as biotic components such as the chemical signatures of dominant plant species and mutualistic and pathogenic microbial populations. While patterns of local adaptation in individual species are widely recorded, the importance of microevolutionary processes for plant community assembly and function is poorly understood.
2. Here we examined how a history of long-term co-existence, and thus potential for local co-adaptation, influenced the process of plant community assembly. Soil inocula and seeds of eight plant species were collected from three calcareous grasslands with a long history of grazing within a single geographical region. Mesocosm communities were established using local genotypes from a single site or an artificial mixture of genotypes from two different sites. To investigate the role of root exudates and local (“home”) and non-local (“away”) soil biot...