Laboratory of yeast genetics, pheromones and speciation Head of laboratory: Guillaume Filion The aim of this practical course is to determine experimentally whether yeast pheromones contribute to speciation. Yeast do not have males and females, but mating types, which are called 'a' and 'alpha'. Type 'alpha' yeast produce a pheromone called the alpha peptide, which attracts type 'a' yeast. When yeast of type 'alpha' and 'a' meet, they fuse and form a diploid hybrid. It is presently unclear whether pheromones are attractive between species. To answer this question, we will use baker's yeast Saccyharomyces cerevisiae. With genetic techniques, we will replace the alpha peptide of Saccyharomyces cerevisiae by the alpha peptides from other species and test whether these transformed yeast can mate with type 'a' yeast. These results will allow us to understand if the evolution of yeast pheromones promotes speciation, or favors the formation of hybrids from distant species.