Hanna, J.W., Klopfenstein, N.B., Kim, M.-S., McDonald, G.I., and Moore, J.A. 2004. Phylogeography of Armillaria ostoyae in the western United States. Annual meeting of the American Phytopathological Society, 31 July to 4 August 2004, Anaheim, CA. poster paper. Phytopathology 94:S38 (Offered poster paper by Hanna)

Using a direct-PCR method, sequences of the nuclear ribosomal DNA (i.e., large subunit, internal transcribed spacer, 5.8S, and intergenic spacer) were obtained from Armillaria ostoyae genets collected from the western United States. Phylogenetic analyses using Bayesian methods defined several groups of A. ostoyae. Analysis of A. ostoyae from outside the western United States indicates the presence of a circumboreal group of A. ostoyae that also occurs in Utah. Phylogeographically unique groups were also present in the Rocky Mountain and Pacific Northwest regions. Other Armillaria species were used as outgroups to examine evolutionary relationships among the groups of A. ostoyae. The occurrence of these groups allows inferences about paleogeographic and paleoclimatic influences on phylogeography of A. ostoyae. Additionally, hybridization has occurred among groups that may have been previously isolated for millions of years. Hybridization has potential implications on species evolution and could contribute to variation in pathogenicity and virulence