An Ecological Study of the Alcohol Dehydrogenase (Adh) Polymorphism of Drosophila Melanogaster.

Abstract

Fluctuations in the numbers of adults of Drosophila melanogaster Mg. in the cellar of a vineyard in Victoria, Australia, were monitored for 5 years. Numbers fluctuated cyclically, from 50 at the end of winter to 100 000 immediately after harvest. Movement within the cellar system was restricted, especially in winter, leading to subpopulations being formed. Overwintering individuals were in a non-breeding quiescent state. These ecological conditions provide considerable potential for random processes. However, such effects did not seem of importance in the maintenance of the Adh polymorphism since concurrent samples in different areas of the cellar had similar gene frequencies, and similar genotypic distributions were observed from year to year in the cellar system as a whole. The relevance of ecological data in distinguishing between random and selective effects acting on enzyme polymorphism in natural populations is emphasised.