FACTORS CONTRIBUTING TO THE HYBRID DYSGENESIS SYNDROME IN DROSOPHILA-VIRILIS

A hybrid dysgenesis syndrome in Drosophila virilis is associated with the mobilization of at least four unrelated transposable elements desi gnated Nelena, Pal is, Penelope and Ulysses. We carried out 42 crosses between eight strains differing in transposable element copy number i n order to assess their contributions to hybrid dysgenesis. Linear reg ression and stepwise regression analysis was performed to estimate the correlation between the difference in euchromatic transposable elemen t number between the parental flies of different strains involved in t he crosses and the percentage, in the progeny of these crosses, of mal es with atrophic gonads. Male gonadal atrophy is a typical manifestati on of the D. virilis hybrid dysgenesis syndrome. About half the variab ility in the level of male gonadal atrophy can be attributed to Penelo pe and Paris/Helena. Other factors also seem to play a significant rol e in hybrid dysgenesis in D. virilis, including maternally transmitted host factors and/or uncontrolled environmental variation. In the cour se of this work a novel transposable element named Telemac was found. Telemac is also mobilized in hybrid dysgenesis but does not appear to play a major causative role.