HYBRID DYSGENESIS DETERMINANTS IN A NATURAL DROSOPHILA POPULATION FROM ALTAI

Localization of mobile elements P and hobo in the genomes of isofemale Drosophila lines obtained from a natural population from Biisk (Altai) was analyzed using in situ hybridization. The average copy number per genome was 27.1 for P and 22.0 for hobo. The highest number of P and hobo copies was recorded in the 3R and 21 chromosomes, respectively. The X chromosome contained the lowest number of hobo copies. For P, this relationship was not shown. Both transposons had preferential localization sites, or ''hot spots'', which partly coincided with intercalary heterochromatin regions. Correlation analysis of P and hobo copy number showed independent distribution of these hybrid dysgenesis determinants. The 1A site, which is thought to be associated with the P-cytotype expression, was not labelled in any line.