My research has been in three areas. 1. Taxonomy and evolutionary systematics. My specialty is ascomycetes, especially the discomycetes (cup fungi). Most specifically, I continue to study the Sclerotiniaceae, a family showing a fascinating array of trophic relationships with plants, some of which are insect-mediated. I use both molecular and morpho-taxonomic approaches. 2. Population processes of fungi associated with agricultural (crops and weeds) or wild plants. I am interested in both population structure and the underlying genetic and phenotypic features of populations. For example, we have identified the emergence of high temperature competence in clonal lineages of a plant parasite after successive years of elevated temperatures and drought. Work in my lab can be either retrospective or experimental. The retrospective studies are based on our sampling from the field from which we infer historic or contemporary relationships that test a hypothesis.Work with the samples starts with multi-locus gene genealogies based on DNA sequences, adds fingerprint and microsatellite data, and explores statistically a wide variety of associations of genotypes,e.g., with geography at scales ranging from global to local, with host or host symptoms, and with genome size. We do a range of experimental studies, from testing phenotype – genotype associations to experimental evolution in which we evolve populations under selection and observe the emergence and increase in frequency of adaptive mutations in real time.