ALCOHOL-DEHYDROGENASE POLYMORPHISM IN POPULATIONS OF DROSOPHILA-MELANOGASTER .3. DIFFERENCES IN DEVELOPMENTAL TIMES

From the F2 ratios of crosses between Drosophila melanogaster strains homozygous for the AdhF(F) and the Adhs(S) allele it has been concluded that the developmental time of FF homozygotes is shorter than that of SS homozygotes. This difference is found to be reinforced by increasing levels of crowding. A further analysis of developmental times has been performed by the transfer of larvae to agar medium after they have stayed for periods of variable length on regular food. From the percentage of emerging adults it can be concluded that FF larvae and, to a lesser extent FS larvae, either reach their critical weights for pupation earlier than SS larvae or possess a lower critical weight. These differences in developmental time influence the course of allele frequencies. Between populations kept on a 2-week transfer schedule and on a 3-week schedule a divergence of allele frequencies is observed, in the former a decrease in S frequency occurs. The relevance of the observed differences in developmental time for the maintenance of the Adh polymorphism is discussed for laboratory populations kept on regular food and at varying densities. © 1979, Cambridge University Press. All rights reserved.