A test of the enemy release hypothesis for plants in the Ecological-Botanical Gardens, Bayreuth, using data on plant parasitic microfungi
Kruse, Julia; Pautasso, Marco; Aas, Gregor
Obligatory plant parasitic micromycetes (Chromista, Fungi) are fungi that subsist and grow on living plant tissues. These fungi comprise a considerable portion of global biodiversity and fulfill important ecological functions. Many species and their host spectra are known only insufficiently. Botanic gardens are particularly well suited for studying these fungi due to the variety of potential hosts and the likely fungal introductions via the exchange of plant material between gardens. The enemy-release hypothesis (ERH), which predicts that exotic species tend to be successful in their introduced range because they leave behind their natural enemies, is particularly relevant for botanic gardens, given their cultivation of many neophytes. This study examined whether the neophytes of three selected plant families (Asteraceae, Betulaceae and Rosaceae) in the Ecological-Botanical Gardens (EBG), Bayreuth, Germany, are less frequently infected by parasitic micromycetes than native plant species of the same family. Native plant species of all three families were significantly more often infected by micromycetes than neophytes, strongly supporting the ERH. Remarkably, neophytes were more frequently infected by native micromycetes than by neomycetes. To the best of our knowledge, this is the first study on micromycetes in a botanical garden to examine the ERH. Botanic gardens provide a test for ecological theory that deserves more research also by mycologists and invasion biologists.