Invasive Buffelgrass, Cenchrus ciliaris, Balances Opportunistic Acquisition of Foliar fungi With Host and Environmental Filtering in Its Introduced Range.

Plants host diverse assemblages of fungi on their foliar tissues, both in internal compartments and on exterior surfaces. When plant distributions shift, they can move with their fungal associates (i.e., co-introduction) or acquire new associates present in the novel environment (host-jumping). The fungal communities that plants acquire influence a plant's ability to establish and spread in this new environment. Here, we aimed to assess whether invasive C. ciliaris hosts similar groups of fungi in its native and introduced ranges and to evaluate community overlap of fungi associated with foliar tissue of C. ciliaris and native and non-native plants within the introduced range. In the introduced range, the majority of OTUs associated with C. ciliaris were not found in its native range, although 3.2% of OTUs were common to both ranges. Of these shared OTU, 77.6% were found on co-occurring natives and non-natives in the introduced range, whereas 22.4% were unique to C. ciliaris indicating a possible co-introduction. Fungal communities within the introduced range contained a higher proportion of generalist symbionts and increased heterogeneity of foliar communities than in its native range. Within the introduced range, host phylogenetic distance explained more variation than native status. Our findings provide evidence that non-natives acquire fungi opportunistically from their environment, although host and environmental filtering is present suggesting that successful invasive plants may be able to limit the effect of poor symbionts and select for better ones. Future experimental work will be needed to confirm the occurrence of host selection and identify its mechanisms.