[Genetic tolerance to alcohol in Drosophila: comparison of the effects of selection in D. melanogaster and D. simulans].

A strain of D. simulans and 3 strains of D. melanogaster having different initial levels of alcohol tolerance were submitted to increasing selection for at least 30 generations. In melanogaster, the relative efficiency of selection was inversely related to the initial level. In simulans, whose natural tolerance is particularly low, only a small increase was obtained. In all cases, tolerance increased progressively and could be considered as a quantitative character. These results are probably due to modifier genes of the alcohol dehydrogenase locus.