Determinants of Hybrid Fitness and Genome Plasticity

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This project will advance understanding of hybrid organisms, which combine genomes from two different species. Hybrids can demonstrate new and desirable traits, performing better in some environments than either of the parent species. Because of this so-called 'hybrid vigor,' hybrids are very important in agriculture, and hybrid yeast specifically carry out many industrially important fermentation processes. Better understanding of hybrids will allow more effective breeding and engineering of improved crops and fermentation microorganisms. Despite this importance, hybrid genomes are not well understood, so this project has the potential to have high impact. In addition to its scientific impact, the project presents numerous training opportunities. A diverse team of undergraduate researchers will perform a significant portion of the experiments, and a postdoctoral fellow and graduate student will be trained in cutting edge genomics techniques. Outreach to the public will include education on yeast biology, fermentation and genome evolution, and the project will engage hobbyist and professional brewers in yeast genetics by enlisting their help to discover new hybrid yeasts.This project will explore a number of open questions in hybrid genomics. It will discover how hybrids are able to adapt to new environments and develop new traits via three potential mechanisms: eliminating genetic conflicts, leveraging genetic variation, and taking advantage of transposon invasion. Studying these hypotheses using naturally derived hybrids can be difficult because their history of growth environments is largely unknown. This project will apply a yeast experimental evolution approach to explore and understand these questions. Hybrids will be created in the lab and evolved under new environments. By sequencing the 'evolved' genomes, new mutations will be identified that have arisen in the population and achieved high frequency. Experiments will determine the relative contribution of genome rearrangements, point mutations, and transpositions to hybrid adaptation. Comparison will then be undertaken with hybrids isolated from industrial and natural fermentations, some of which will be collected by brewers as part of this project. All together, the project will lead to better understanding of the molecular mechanisms important for hybrid vigor and adaptation.This award is supported jointly by the Genetic Mechanisms program in the Division of Molecular and Cellular Biosciences and by the Environmental Sustainability program in the Division of Chemical, Bioengineering, Environmental and Transport Systems.