A long-term study on seasonal changes of gametic disequilibrium between allozymes and inversions in Drosophila subobscura

Seasonal variation (spring, early summer, late summer, and autumn) of gamet ic disequilibrium between gene arrangements (O-ST and O3+4) of the O chromo some and Lap, Pept-1, and Acph allozyme loci, located inside these inversio ns, has been recorded in a natural population of Drosophila subobscura duri ng seven years over a 15-year period. The length of the study allowed us to investigate the temporal variation of the allozyme-inversion associations by statistical methods of time series analysis. Cyclic seasonal changes of allozyme-inversion associations for both Lap and Pept-1 are detected in the natural population. In both cases, the patterns of seasonal change are due to the seasonal change of frequency of Lap and Pept-1 allozymes occurring exclusively within the O-ST gene arrangement. In contrast, the allozyme fre quencies at these loci within the O3+4 gene arrangement are stable along se asons. The patterns of temporal variation of allozyme-inversion association s for Lap and Pept-1 in the natural population are contrasted with those pr eviously published that correspond to gene arrangements of the O chromosome and nucleotide polymorphism at the rp49 region located inside these invers ions, suggesting that natural selection is operating on these allozyme-inve rsion associations.