Effects of Radiation on Populations of Drosophila Melanogaster with Different Genetic Structures II. Temporal Changes in the Sex Ratio

Abstract

The effect of 1500 r X.rays, delivered for several generations to populations of D. melanoga8ter, on the sex ratio of the flies emerging has been examined. The results have been compared with those from similar populations living in the same environment but not given any radiation treatment. The mean values of four irradiated populations, when compared with their unirradiated counterparts, showed an initial drop in sex ratio followed by a marked recovery particularly between generations 7 and 12. When composite populations were set up, combining males from one irradiated population with females from another at each generation, this recovery in sex ratio was not observed. It was concluded that this latter result ruled out chromosomal phenomena and indicated a biometrical explanation as the most likely one for the observed rise in sex ratio with accumulated ancestral radiation in integrated gene pools