ADVANCE Fellows Award: Exploring Genome Plasticity During Speciation in Hybrid Yeasts

Stanford University, Stanford CA

Investigators

Abstract

Genome rearrangements have been implicated as a driving mechanism in the speciation of many organisms. Using microarray-based Comparative Genomic Hybridization (array-CGH), this investigator will track, on a whole-genome scale, the chromosomal rearrangements that occur during each step of de novo speciation in hybrid yeasts formed between Saccharomyces cerevisiae and each of the four other sequenced Saccharomyces species. Array-CGH techniques will also be used to similarly investigate whether the nascent hybrid yeast species, when grown in chemostats under differing conditions, exhibit characteristic sets of genome rearrangements that can be correlated with specific environmental pressures, and to determine the stability of these genome rearrangements during long-term growth. Finally, a "genomic survey" of industrial yeast strains (such as beer, wine, and baking yeasts) will be performed, using array-CGH to inventory strain-specific chromosomal composition and genomic rearrangements. These studies will represent the first genome-wide assessment of the extent and types of genome rearrangements that occur during real-time speciation and adaptation. They will allow elucidation of not only potential mechanisms of genome rearrangement, but also potential mechanisms of speciation. By establishing whether specific large-scale genome rearrangements are associated with specific selective pressures, the role that genome plasticity plays in adaptive evolution can be assessed. Finally, by retrospectively examining the genomes of contemporary industrial yeast strains and comparing the results to those obtained from the lab studies described above, it may be possible to identify the historical events, in the form of selective pressures or hybrid formation, that led to particular genome structures for particular industrial uses.