MOBILE ELEMENTS AND SPECIATION

A new system of hybrid dysgenesis in Drosophila virilis is described. Dysgenic crosses in this species result in mobilization of several fam ilies of mobile elements (ME): Ulysses, Penelope, Helena, and Paris, c ausing hybrid sterility, mutations, and other disorders. The distribut ion of ME in different geographic populations of D. virilis and other species of the virilis group was studied. It was found that, contrary to other ME, the Penelope capable of inducing the hybrid dysgenesis sy ndrome is not present in all populations of D. virilis. Basing on thes e data and on the results of chromosomal localization of Penelope and other ME, we conclude that the D. virilis genome is now being invaded by Penelope. The sites of chromosomal localization of ME coincide ofte n with the inversion breakpoints described for the virilis group speci es. Hence, dysgenesis may play the key role in mobilization of ME and in induction of chromosomal rearrangements at the early phase of speci ation process.