Seasonal variation in endoreduplication and polyteny in the fruit fly Drosophila melanogaster (Diptera: Drosophilidae): How does it contribute to adaptation?

In temperate regions, the fruit fly Drosophila melanogaster (Meigen, 1830) is subject to seasonal changes in conditions. Insects exhibit a wide range of adaptive responses to changes in the seasons. In this study, we focused on which plays an important role in fruit fly development. Polytene chromosomes are the result of endocycles, a variant of cycle based on endoreduplication. This phenomenon is the basis of postmitotic growth, which is caused by cell expansion. purpose of the study was to investigate the seasonal dynamics of the levels of endoreduplication and polyteny in fruit flies from the natural population. Flies caught in the spring and autumn of 2019 and 2020 were used as biological material. somal differences in polyteny were studied by cytomorphometry. We found that patterns of polyteny in Drosophila salivary undergo seasonal changes. To a certain extent, these variations correlate with changes in the direction of natural selection, undergoes seasonal fluctuations. Indices of endoreduplication and cell ploidy acquire the greatest values after overwintering, ing which there is an extreme decline in population size and flies undergo selection for viability and stress resistance. During growing season, endoreduplication and ploidy indicators are reduced. We believe that this facilitates population growth by ing in smaller flies with accelerated development and faster change of generations. The seasonal component in the total of chromosome polyteny in the salivary glands of Drosophila larvae was 21.9%. No significant sex differences were found trait.