I do experiments with yeast to investigate the process of evolution and to test evolutionary theories. Baker's yeast (Saccharomyces cerevisiae) is an ideal laboratory model organism because it's a sexual eukaryote (just like us), but it reproduces and evolves very quickly, its genome is simple and well defined, and it's easy to genetically engineer. My work spans several research areas including the origin and maintenance of species, the evolution of social cooperation and conflict, sexual selection, and the evolution of sex. I'm interested in the genetics, ecology, and natural history of wild yeast populations, and I collaborate with a mechanical engineer colleague building electrospray devices for manipulating living cells. I'm also interested in the interaction between science and the arts. A long-term research goal has been to dissect out the genetic causes of sexual sterility in hybrids formed between Saccharomyces cerevisiae and other closely-related yeast species. It's important because hybrid sterility acts as a barrier, preventing different species from mixing and becoming one. I've found that the molecular basis for the species barrier in yeast is quite different from what was expected. In other experiments, I've studied the production of extracellular molecules (beneficial enzymes and harmful toxins) that allow yeast individuals to interact socially with others, in a state of either cooperation or conflict. And recently I've been looking at how yeast uses a sexy chemical signal, a pheromone, to attract mates. The sex pheromone works like a peacock's tail, and we can use it to study how such signals evolve, what information sexual signals convey to potential mates, and what the benefits and costs of signalling (and responding to signals) are.