The idea that part of the genetic material, DNA, consists of tiny "parasites" is a relatively new concept. But these transposable genetic elements -- also known as jumping genes -- contribute to much of the spontaneous mutation in many organisms and have been adapted as tools for molecular biologists who use them to move genes in and out of chromosomes. Yet, many questions remain unanswered. "We don't know how they got there, how they survive, why they don't cause more damage, where they're distributed and how many there are," says UC Davis genetics professor Charles H. Langley. Accounting for 1 to 40 percent of all organisms' genomes, jumping genes seem to exist only for the purpose of reproducing themselves, which is why they are frequently described as "selfish DNA." The spread of these genetic parasites seems to be contained by mechanisms beyond simple natural selection. In studies of Drosophila, Langley has tested the predictions of several theories about the dynamics of transposable elements in natural populations. Langley will review the population genetics of Drosophila's jumping genes and compare recent results to theoretical predictions during the morning session titled "Evolutionary Genetics of Transposable Elements," Tuesday, Feb. 11, in Grand Ballroom A.