Background/Question/Methods: The biogeographic patterns associated with the autecologies of fungi are poorly understood. Using both historical records and molecular data, we have established the fungus Amanita phalloides as an introduction currently expanding its range on the West Coast of North America. The species is native to Europe. Although is has also been introduced to the East Coast of North America, on the East Coast A. phalloides grows as isolated populations and is not spreading. We collected mapped populations of fungi from California, Europe, and the Northeast U.S., and used AFLP protocols to create genetic fingerprints of each mushroom.
Results/Conclusions: Most mushrooms in a habitat are unique genetic individuals. Data suggest that genets of A. phalloides are typically less than 1 m in diameter, and the pattern holds across California, Europe, and the Northeast, and is the same for sites where populations are assumed to be young, and sites where A. phalloides has been collected for over 30 years. There appears to be no correlation between body size and the geographic origin or age of a population. In contrast, although the mushrooms of A. phalloides appear at specific times of year in Europe and on the East Coast, in California mushrooms can form at any time of year. Moreover, mushrooms are twice as large in California, as compared to mushrooms on the East Coast or in Europe.