Poster #3

Can mushroom toxins enable a biological invasion? Testing enemy release and novel weapons hypotheses with invasive death caps
C.K. STOKES, S. C. PARK, Z. ZARETZKE, N. P. KELLER, M. J. JUSINO, AND A. PRINGLE.
University of Wisconsin-Madison, Department of Botany, 430 Lincoln Drive, Madison, WI 53706

Amanita phalloides (the death cap) is a deadly and invasive ectomycorrhizal mushroom. After being introduced to the United States from Europe, A. phalloides became widespread in California, and the fungus is now abundant in endemic coastal live oak woodlands. Death caps produce diverse secondary metabolites, including amatoxins responsible for killing humans, but why toxins are produced in nature remains unanswered, and whether they play a role in invasions is unknown. Building on long-standing claims from literature, we hypothesize the toxins play an essential role in death cap ecology, acting as a defense against invertebrates. In 2023 we collected cap tissues from A. phalloides and other Amanita growing in both native and invaded ranges. After documenting the chemistry in each mushroom, we are characterizing the invertebrate communities using metabarcoding of the mitochondrial cytochrome oxidase subunit 1 region. We are using multivariate hypothesis testing to statistically compare differences in community composition among mushrooms, between the invaded and native ranges, and across toxin levels. Investigating differences in invertebrate communities in mushrooms from both ranges allows us to test both the enemy release and novel weapons hypotheses. Discovering the role of the death cap’s toxins is integral to understanding the mechanisms behind its invasion.