When Fungal Blind Spots Spill Over: How Knowledge Gaps Undermine Invasion Science and Conservation

Knowledge gaps in fungal biodiversity not only limit conservation efforts but also progress in other research fields, including invasion science. Biological invasions of fungi and fungus-like organisms can strongly impact native biota and human livelihoods. Non-native pathogens may encounter naïve hosts, potentially causing significant declines in native species and altering communities. Examples include ash dieback in Europe, myrtle rust in the Southern Hemisphere, and chytridiomycosis impacting amphibians worldwide. Co-introduced ectomycorrhizal fungi can facilitate plant invasions, as shown for pines in the Southern Hemisphere, while saprobes influence nutrient cycles. Yet the consequences of fungal invasions for native fungal communities and the ecosystem functions and services they underpin remain largely unexplored.

Invasion science historically focused on plants and vertebrates, and despite fungi increasingly gaining attention, major knowledge shortfalls in species diversity, geographic ranges and hosts hamper this progress. Non-native species checklists are biased towards plant pathogens. Ectomycorrhizal fungi, which, due to their close host association, are expected to have similar introduction pathways, are much less well represented. A global quantification of non-native plant pathogen-host associations indicates that over half of all recorded associations in the pathogens’ non-native ranges involve novel associations with native plants or co-xenic associations with non-native plants that do not co-occur in the pathogen’s native ranges. Strikingly, over 40% of records could not be confidently classified due to insufficient information on pathogen biogeography, also highlighting knowledge gaps regarding hosts in the pathogens’ native range. These may bias estimates of host breadth and host shifts, weaken risk assessments, and propagate into conservation decisions that rely on robust distribution and interaction data.

These examples highlight how missing knowledge on fungal diversity and distribution not only constrains conservation efforts but also the capacity to anticipate and manage biological invasions. Addressing gaps through coordinated monitoring following best practices and standards resulting in interoperable, curated datasets that link occurrence, host associations and biogeographic status metadata will enhance the ability to detect, understand, and mitigate the consequences of fungal invasions. Ultimately, a holistic approach to fungal biodiversity recognizes that conservation and invasion science are mutually dependent: advancing one relies on advancing the other.