AMF, phylogeny, and succession: specificity of response to mycorrhizal fungi increases for late-successional plants

Arbuscular mycorrhizal (AM) fungal communities are important to plant community productivity and diversity; however, the importance of AM fungal composition to community dynamics remains largely unknown. Specificity of plant response to different AM fungal species is a prerequisite for AM fungal composition to have an effect on plant community dynamics. We test determinants of specificity of plant response to AM fungi across six early-and six late-successional tallgrass prairie plants by growing them with one of seven different AM fungal species and a non-inoculated control. We found that late-successional species were more responsive, and demonstrated greater specificity, toward individual AM fungal taxa than early-successional species. There was no phylogenetic signal for plant responsiveness or specificity of plant response. Phylogenetic multiple regressions indicated that successional stage, plant growth rate, and overall responsiveness were significant predictors of fungal specificity independent of shared phylogeny. These results suggest that plant response to mycorrhizal fungi is evolutionarily labile and coevolves with plant life history. Our results also suggest that AM fungal community dynamics can be particularly important for the establishment and subsequent dynamics of late-successional plants.