A STUDY OF FREQUENCY-DEPENDENT SELECTION OBSERVED IN THE ESTERASE-6 LOCUS OF <i>DROSOPHILA MELANOGASTER</i> USING A CONDITIONED MEDIA METHOD

Abstract

an earlier paper, which had not changed genotype frequencies at several loci for more than 45 generations. Furthermore, the intensity of selection appeared to depend upon the degree of deviation from the equilibrium gene frequency. The greater the deviation, the more intense was the selection pressure toward the equilibrium frequency. A similar but more carefully designed experiment, using Drosophila melanogaster's alcohol dehydrogenase ( A D H ) locus with two alleles, showed a similar result for viability as those of the Est-6 experiment cited above (KOJIMA and TOBARI 1969a). This mode of selection was called frequency-dependent selection by these authors. In this paper, alleles esterase-6F and -6s are abbreviated as F and S, respectively.