Selection acting upon slow-migrating ADH alleles differing in enzyme activity.

Relative egg to adult viability was compared in three stocks of Drosophila melanogaster differing in alcohol dehydrogenase (ADH) activity. Two of these, Grell's standard ADHS and a mutant ADHS strain producing half the normal number of ADH molecules, had the same electrophoretic mobility. The experiment demonstrated a correlation between survival in alcohol-supplemented media and enzyme activity. This supports the hypothesis that enzyme activity per se, rather than some other attribute of allelic differences, may be responsible for the previously observed selective advantage of high activity alleles on alcohol media.