A TRANSPOSABLE ELEMENT CAN DRIVE THE CONCERTED EVOLUTION OF TANDEMLY REPETITIOUS DNA

Recombination and conversion have been proposed to drive the concerted evolution of tandemly repeated DNA sequences. However, specific corre ction events within the repeated genes of multicellular organisms have not been observed directly, so their nature has remained speculative. We investigated whether the excision of transposable P elements from tandemly repeated sequences would induce unequal gene conversion. Gene tically marked elements located in a subtelomeric repeat were mobilize d, and the structure of the region was analyzed in progeny. We observe d that the number of repeats was frequently altered. Decreases were mo re common than increases, and this bias probably resulted from intrins ic mechanisms governing P element-induced double-strand break repair. Our results suggest that transposable elements play an important role in the evolution of repetitious DNA.