A Method for the Direct Study of Natural Selection

Abstract

Decisive experiments on selection of mutants of Drosophila melanogaster can be carried out under natural conditions in Britain where this species is not indigenous. This communication records an experiment in which a balanced population containing 25 % ebony mutants was released in South Devon. The frequency of the genotype among the descendants was estimated after a period equivalent to six discrete generations, by testing trapped flies, most of which were wild type in appearance, for heterozygosis. The frequency estimated was very close to what would be deduced on the assumption that elimination of the recessive type before maturity was complete.