Rytas Vilgalys, PhD
Professor
Department of Biology

My research program uses the techniques of molecular biology as well as more conventional approaches (culturing, mating studies, etc.) to answer questions about the natural history of fungi. Current research is focused on three areas:

1. phylogenetic biology and systematics, especially of the Agaricales (mushrooms).
2. genetics of speciation, including patterns of morphological vs genetic divergence, and analysis of the genetic factors underlying development of intersterility between related species.
3. population biology of fungi, estimation of breeding systems and measurement of gene flow in natural populations. Fungi currently under investigation include the oyster mushroom (Pleurotus ostreatus) as well as several species of medically important fungi (Candida albicans and Cryptococcus neoformans)

Phylogeny: The major research effort in our laboratory for the last 10 years is still aimed at understanding molecular evolution of ribosomal RNA genes in fungi, and their use for estimating evolutionary relationships of the higher Basidiomycotina. We are presently surveying rDNA sequence variation from various families of the Agaricales (mushrooms) and related fungi.

Speciation: Saprobic basidiomycetes offer an excellent system for studying the meaning of "what is a species" in fungi. Our research combines the study of morphology, mating behavior, genetics and molecular systematics to try and understand how species differ and how they evolve. Mating compatibility studies have repeatedly demonstrated strong intersterility barriers among most species. Our previous studies on DNA-level variation in the mushroom Collybia dryophila revealed a surprisingly high degree of genetic divergence associated with speciation among intersterility groups. More recently, our studies of speciation in the oyster mushroom genus Pleurotus have examined the importance of biogeography as a primary factor associate with speciation.

At the molecular level, genomes of mushroom species also appear to 'turn over' more rapidly than other eukaryotes. We are currently employing molecular approaches to study genetic mechanisms which may operate during speciation. These methods include the use of DNA restriction fragment polymorphisms (RFLPs) and Amplified Fragment Length Polymorphisms (AFLP) to estimate genetic diversity and along with electrophoretic karyotyping, as well as more conventional methods based on mating compatibility studies. One of the current objectives of this research will be to develop a generalized model for genome evolution in Basidiomycotina and its role in the development of intersterility barriers (speciation).

Population Biology: Unique features of fungal life history have profound relevance for their population biology. We have been investigating the significance of mating systems and life history for determining genetic structure using molecular markers, both in wild mushroom species (Pleurotus ostreatus and Schizophyllum commune) as well as in several human pathogenic fungi (Candida albicans and Cryptococcus neoformans, in collaboration with Dr. Thomas G. Mitchell of the Duke University Medical Center). A variety of approaches and markers are being employed to addresses questions ranging from how far do spores disperse, to how much clonality vs recombination occurs in natural populations.