Differential flight activity among karyotypes: daily and weather-induced changes in chromosomal inversion polymorphism in natural populations of Drosophila subobscura.

The question is posed whether karyotype frequencies in the active fraction of Drosophila subobscura populations vary consistently in the course of a day, or in accordance with weather changes. Significant daily variation occurred in all chromosomes with the exception of the sex chromosome. The proportions of the karyotypes Ust/1+2 and Ist/st decreased from early to late morning and increased during the evening. Ist/1 displayed a complementary behaviour. The homokaryotypes Ost/st and Est/st decreased both during the morning and the evening. Weather disturbances caused a remarkable variation in the frequencies of the standard gene arrangements.