Embracing the good and escaping the bad? Eco-evolutionary shifts in fungal interactions associated with a cosmopolitan weed
Y. LEKBERG , M. SHENG, C. ROSCHE
MPG Ranch & University of Montana, 1001 S. Higgins Ave, Suite A3, Missoula, MT 59801

Prominent hypotheses in invasion biology, such as the Enemy Release and the Enhanced Mutualism Hypotheses, are based on biogeographical shifts in biotic interactions. Fungi can both suppress and enhance plant growth, yet careful surveys of plant-fungal associations across ranges are rare. We surveyed fungal communities interacting with a global invader, Conyza canadensis , across ranges spanning similar climate and soil fertility gradients. We paired field surveys with a plant-soil-feedback (PSF) experiment where Conyza populations were grown in soil from the native range. In the field, non-native Conyza were larger, more fecund, and associated with a richer community of arbuscular mycorrhizal (AM) fungi. Non-native Conyz a also interacted with different putative pathogens than native Conyza–a pre-requisite for enemy release–and pathogens tended to be more abundant in the rhizosphere than roots. In the PSF experiment, native and non-native populations amplified different fungal communities, which coincided with less negative PSF responses in non-native Conyza populations. Our findings indicate rapid evolutionary shifts in plant-fungal associations that may promote invasiveness whereby non-native Conyza promotes better mutualists and more benign pathogens than native Conyza . We will relate findings to other studies, discuss potential underlying drivers that may trigger evolutionary shifts, and propose future research.