ADAPTIVE TRANSPOSITIONS OF RETROTRANSPOSO NS ACCOMPANIED BY FITNESS CHANGES IN THE DROSOPHILA-MELANOGASTER GENOME

Two cases of spontaneous transpositions of MDG1, MDG3, and copia retro transposons were detected in Drosophila melanogaster lines derived fro m the nonadaptive NA line and marked by recessive visible mutations. T he transpositions were accompanied by a dramatic increase in individua l fitness (competitive success). In independent instances of MDG1 tran spositions, the location patterns of new sites were similar. These res ults confirm the existence of adaptive transpositions that were demons trated earlier for the NA line that carried no visible markers.