The effect of heterozygous autosomal inversions on induced exchanges between the attached-X and Y chromosomes in Drosophila melanogaster females.

INCE the original observation of STURTEVANT (1919) a large body of data has accumulated substantiating the contention that, in Drosophila melanogaster females, inversion heterozygosity in one part of the genome increases the frequency of recombination in the remainder of the genome. This effect has been demonstrated for spontaneous meiotic crossing over (see, for instance, SCHULTZ and REDFIELD 1951; RAMEL 1962; SUZUKI 1963), and for spontaneous somatic crossing over (BROWN and WELSHONS 1955; RONEN 1964). COOPER (1946) studied the effects of autosomal inversions on the frequency of spontaneous exchanges between attached-X and Y chromosomes and reported that heterologous structural heterozygosity had no effect on the rate of detachment of the attachedX. The purpose of this paper is to present experimental evidence of a significant increase of induced exchanges between the attached-X and Y chromosomes when heterozygous autosomal inversions are present in the genome.