Fitness components at the octanol dehydrogenase locus in Drosophila melanogaster.

Experiments were performed to study the fitness at the Odh locus in Drosophila melanogaster. Populations previously treated with alcohol (5% in the medium) were transferred to media containing more (10%) or no alcohol. Odh genotype frequencies of second instar larvae and mature adults were determined in each generation. Selection appeared at a significant level in both experimental populations. Net fitness and larva-to-adult survival were investigated. To interpret our results the constant and frequency-dependent models of selection were tested. Both larva-to-adult survival and net fitness were found to be significantly correlated with genotype frequencies. Thus the frequency-dependence of net fitness was due to the larva-to-adult survival.