AN ANALYSIS OF MALE-RECOMBINATION ELEMENTS IN A NATURAL POPULATION OF DROSOPHILA MELANOGASTER IN SOUTH TEXAS

Genomes from a group of Drosophila melanogmter collected from a natural population at San Benito, South Texas, in March of 1975 were analyzed for the presence of male-recombination elements. All three autosomes and both sex chromosomes were examined, with emphasis placed on the two major autosomes, the second and third chromosomes. In samples of 16 second and 16 third chromosomes, at least half, but not all, of each were found to carry male-recombination elements. It is suggested, although the data are not conclusive, that some of the fourth, X, and Y chromosomes might also be associated with male-recombination elements.—When a male-recombination element, or elements, was located in the second chromosome, relatively more male recombination was induced in the second than in the third chromosome. This situation was reversed when the element(s) was located in the third chromosome.—Distortion of transmission frequency, one of the characteristics of previously studied second chromosome lines associated with male recombination, was confirmed for these second chromosomes that carried male-recombination elements. Similar, but less pronounced, distortion was observed for the third chromosome lines that carried male-recombination elements.