GENE CONVERSION IS INVOLVED IN THE TRANSFER OF GENETIC INFORMATION BETWEEN NATURALLY-OCCURRING INVERSIONS OF DROSOPHILA

The DNA sequences of the ribosomal protein 49 (rp49) region were deter mined for 34 isochromosomal strains of Drosophila subobscura represent ing two chromosomal arrangements, the O-ST and the O-3+4 gene arrangem ents, which differ by two overlapping inversions. The data reveal that gene conversion is a mechanism responsible for the transfer of geneti c information between naturally occurring inversions of Drosophila. Th e estimated rate of gene transfer by gene conversion at this region, w hich is close to an inversion breakpoint, is lower than previous estim ates obtained experimentally at the rosy (ry) gene in Drosophila melan ogaster. Our data indicate that gene arrangements O-ST and O-3+4 are m onophyletic and rather old (0.58 and 0.73 million years old, respectiv ely).