Seasonal Cycles and the Concentration of Inversions in Populations of Drosophila funebris

Abstract

The urban populations show a high saturation of inversions; the rural, a very low percentage. In addition, there is a marked seasonal fluctuation of inversion percentages in the urban population which does not occur in the rural. In the urban populations, the inversion percentages are 1.8 to 15 times greater during the summer than in the winter when fly populations are greatly reduced. Dichotomy between urban and rural populations indicates rapid evolutionary changes.