| This dissertation is composed of two parts. The first part deals with the phylogenetic distributions and limits of club and coral (clavarioid) fungi in the families Clavariaceae (Chapter 1) and Pterulaceae (Chapter 2) using molecular phylogenetic methods. The second part, also composed of two chapters, focuses on the systematics and evolution of porcini mushrooms. In chapter one, at least six independent origins of clavarioid mushrooms were identified by an analysis of a large dataset (971 sequences) composed of agaricoid, corticioid, and clavarioid mushrooms. Alloclavaria Dentinger & McLaughlin, genus novum, was erected based on the phylogenetic position of Clavaria purpurea Fr. in the Hymenochaetales. Fine-scale analyses of each of the clades containing clavarioid taxa were conducted separately and are interpreted in light of the evolution of fruit body morphologies and with attention to resolving current taxonomic ambiguities. The second chapter focuses on the evolution of the Pterulaceae in the context of the attine ant-fungus mutualism. Free-living pterulaceous fungi are identified as the closest relatives to one ant cultivar lineage, contradicting an existing hypothesis that the cultivars form a clade of domesticated fungi. Moreover, the closest free-living relatives of the fungal cultivars produce sterile mushrooms, an unusual coincidence that may have coevolutionary implications. The third chapter focuses on the edible fungi known as porcini, a complex of fleshy, pored mushrooms (boletes). The hypothesis that porcini are a monophyletic group is evaluated using molecular phylogenetic analysis of multiple independent nuclear loci and explicit hypothesis testing. Although the monophyly of porcini is only weakly supported by a single-locus dataset, the hypothesis that they are monophyletic could not be rejected. The final chapter uses a subclade of iv porcini as a model to explore the evolution of specialization in ectomycorrhizal fungi. Ancestral state reconstructions using a species-level phylogeny of porcini reveals at least one well-supported derivation of a generalist from a specialist ancestor and rejects the hypothesis that specialists or generalists are evolutionary "dead-ends."... |
