Genetically Engineering Yeast to Understand Molecular Modes of Speciation

An understanding of the molecular mechanisms of speciation (reproductive isolation) is potentially very powerful as it should help us appreciate the processes that differentiate closely related organisms such as humans and chimpanzees. Currently, however, our understanding of such mechanisms is far from complete. The closely related yeast, Saccharomyces cerevisiae and Saccharomyces mikatae, represent ideal species to use to study molecular modes of speciation as the genomes of these of organisms have been sequenced [1] and are readily genetically manipulated. S. cerevisiae and S. mikatae are capable of mating, but the resulting hybrids are almost always sterile. Three molecular models often used to explain reproductive isolation include chromosomal rearrangements, simple sequence divergence upon which the mismatch repair system acts, and genetic incompatibility. In this proposal an outline of a genetic engineering based approach to characterize the roles of these mechanisms in the reproductive isolation of S. cerevisiae and S. mikatae is presented.