GENE DIFFERENCES BETWEEN THE SEX RATIO AND STANDARD GENE ARRANGEMENTS OF THE X CHROMOSOME IN DROSOPHILA PERSIMILIS

David Policansky 1 and E. Zouros 2

1 Department of Biology, University of Massachusetts, Boston, Massachusetts 02125
2 Department of Biology, Dalhousie University, Halifax, Nova Scotia B3H4J1

The sibling species Drosophila pseudoobscura and D. persimilis each carry two gene arrangements in the right arm of the X chromosome; Standard (ST) and Sex Ratio (SR). The SR sequence of D. persimilis and the ST sequence of D. pseudoobscura have the same banding pattern. These cytologically identical arrangements carry different alleles at the esterase-5 (Est-5) and phosphoglucomutase-1 ( Pgm-1) loci. All the alleles on the SR arrangement of D. persimilis are also present on the ST arrangement of that species, and the same allele was most common in all cases. However, the allele frequencies at the Pgm-1 locus are significantly different between the two arrangements. Within the ST arrangement of D. persimilis, the alleles at the Est-5 and Pgm-1 loci are in linkage equilibrium.

Submitted on March 24, 1976
Revised on August 25, 1976