Phylogenetic trait conservatism predicts patterns of plant-soil feedback

Plant-soil feedbacks (PSFs) are important drivers of plant community structure and diversity, with species varying in the way they both condition soils and respond to them. While plant phylogenetic relationships alone can predict this variation in some instances, trait conservatism across phylogenies may provide more reliable predictions. Using integrated common garden and glasshouse inoculation experiments including 13 Eucalyptus species across two subgenera, we specifically investigated soil microbial conditioning and root chemical traits as underlying drivers of phylogenetic differences in PSF. We found that eucalypt species responded variably to soils conditioned by closely related species, depending on their phylogenetic lineage, which was further related to root terpene concentrations and the presence/absence of specific fungal taxa in conditioned soils. Overall, these findings show that trait conservatism in root chemical traits and the subsequent conditioning of soil microbial communities can explain whether or not plants show phylogenetic patterns in PSF.