Transposable elements are stretches of DNA with the ability to insert themselves, or copies of themselves, into new sites in the genomes of their hosts. This project will study how the force of natural selection affects the maintenance and distribution of these elements. These questions will be addressed by examining DNA sequences of the transposable element Ty3 in natural isolates of two yeast species: Saccharomyces cerevisiae (the common brewers' and bakers' yeast) and its close relative Saccharomyces paradoxus. The amount and type of variation in Ty3 DNA sequences will be analyzed to reveal how natural selection is acting on Ty3 elements in these populations.
Transposable elements have been discovered in virtually every organism with a well-characterized genome, including the human genome. The movement and replication of these elements is a major source of harmful genetic mutations, and this observation has led to the theory that transposable elements are DNA parasites. This "selfish DNA" hypothesis remains to be tested rigorously in diverse natural populations of organisms. The project described in this proposal focuses on the primary organism studied in modern genomic research (yeast) and integrates genomic and molecular methods with evolutionary approaches to further our understanding of the biological significance of transposable elements.
