Population Genetics of Transposable Elements

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9527717 CHARLESWORTH Transposable elements (TEs) are DNA sequences that are present in multiple copies in the genomes of most organisms, including humans. They can make new copies of themselves, which can insert into new places in the genome. Sometimes these insertions cause mutations of nearby genes, and a number of mutations involved in human genetic diseases have originated this way. It seems clear that TEs behave, at least in part, as parasites on the genomes of their hosts, using them as a vehicle for their own transmission. The forces responsible for controlling the abundances of TEs in the genomes of their hosts are a matter for continuing research. Understanding these forces is important for our knowledge of the factors that shape the organization of the genome, and for the origin of mutations. The fruitfly Drosophila is a useful model organism for research into these questions. The properties of TEs are similar in Drosophila and other organisms such as humans; in Drosophila the short generation time and ease of study allow genetic questions to be addressed much more efficiently than in larger organisms. The proposed research continues an investigation of the population-level properties of Drosophila TEs. A major objective is to obtain more precise estimates of the rates at which Drosophila TEs move around the genome; this information is vital for interpreting previous studies of the distribution of TEs between individuals. A second objective is to examine TEs that are inserted at a particular site in the genome in all studied individuals. These cases are exceptional, as the adverse effects of TE insertions usually mean that TE insertions are found only at low frequencies at a given location.