Genetic instability in Drosophila melanogaster

Summary

A tandem duplication of the w ⁺locus in Drosophila melanogasteris described. This duplication can exist in two distinctive states. In one state the duplication functions to evoke the zeste eye color phenotype in males. In the alternative state the duplication cannot so function. Spontaneous changes in state occur in both males and females. These changes are recovered as clusters in the absence of crossing over suggesting a premeiotic occur of the “mutation” event. In addition spontaneous male viable w deficiencies,are recovered from the tandem duplication existing in either functional state. These deficiencies, often recovered as clusters, originate in both males and females. It is suggested that these mutational events are causally associated with a segment of “foreign” DNA which has been mapped to the duplication. The nature of the mutational event is discussed.