Biogeographically novel associations and host range breadth of alien fungal and fungus-like plant pathogens
A. SCHERTLER, B. LENZNER, S. DULLINGER, D. MOSER, A. GARCIA, I. GREILHUBER, H. VOGLMAYR, J. BUFFORD, A. SANTINI, L. GHELARDINI, C. CAPINHA, M. MONTEIRO, L. REINO, M.J. WINGFIELD, H. SEEBENS, M. THINES, W. DAWSON, M. VAN KLEUNEN, H. KREFT, J. PERGL, P. PYŠEK, P. WEIGELT, M. WINTER, F. ESSL
Division of BioInvasions, Global Change & Macroecology, Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, Vienna 1030, Austria

While the spread of alien fungal and fungus-like plant pathogens can have profound effects on biota, those may depend on interactions arising - ranging from co-introduction to biogeographically novel associations resulting from spill-over to native or other alien plants. Here, we investigate pathogen-plant associations globally and characterize the type of association in the pathogens’ introduced range, by utilizing global databases on regional distributions and associations. Specifically, we i) assess the frequency of novel associations in the pathogens invaded range, ii) examine the alien pathogens host species richness and phylogenetic divergence within host assemblages, and iii) investigate which alien pathogens, plants and regions are most likely to experience novel associations.

Biogeographically novel associations were common, observed in about one-third of alien plant pathogens and predominantly within their known phylogenetic host range. Novelty of associations is positively associated with globally widespread alien pathogens that show higher phylogenetic divergence in their host assemblages, and that co-occur on economically used hosts in the same region and with geographically restricted tropical woody plants without economic use. Importantly, a substantial proportion of associations could not be classified, highlighting the need to further improve our knowledge of fungal biogeography to better understand the consequences of fungal invasions.