| Summary: | This dissertation is an investigation of the systematics, phylogeography, and ecology of a globally distributed fungal family, the Elaphomycetaceae. In Chapter 1, we assess the literature on fungal phylogeography, reviewing large-scale phylogenetics studies and performing a meta-data analysis of fungal population genetics. In particular, we examined the possible effects of asexuality, trophic niche, dispersal method, and ocean barriers on population structure. In Chapter 2, we examine the systematics and phylogeography of the Elaphomycetaceae, a family consisting of the truffle genus Elaphomyces and the stalked genus Pseudotulostoma, hypothesizing that the mammal-dispersed truffle would show evidence of dispersal limitation. Using DNA sequence data, we determined that Pseudotulostoma is derived from a lineage of Elaphomyces, indicating that Elaphomyces as currently defined is paraphyletic. The distribution of each subgenus of Elaphomyces is nearly global; representative species have been found on every continent save Africa and Antarctica. This biogeographic pattern does not follow the pattern expected by a scenario of continental vicariance. Dating analysis in BEAST confirmed that broadly distributed clades are, in most cases, too young for this pattern to be explained by continental vicariance, indicating that occasional long-distance dispersal has been a significant component in the biogeographic history of the Elaphomycetaceae. This finding contradicts our initial hypothesis that the mammal-dispersed truffles would be dispersal- limited. In Chapter 3, we investigate the role of Elaphomyces as a host for the fungal parasite Elaphocordyceps, a parasite derived from insect pathogens that attacks both insect larvae and Elaphomyces, its only fungal host. We examined the biogeography of Elaphocordyceps isolated from Elaphomyces specimens in order to test whether it, like its host, showed recent connections between the Southern and Northern Hemispheres. We also evaluated the pathogenicity of infection as determined ...
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