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Seasonal fitness parameters and selection indices in the natural population of Drosophila melanogaster Meig.

Aim. The purpose of investigation was to study the seasonal selection indices and its components in the natural population of Drosophila melanogaster Meig. Methods. The material for the study was the Gaidary-spring and Gaidary-autumn lines, obtained from the natural population of Gaidary in different seasons of the year. Fecundity and mortality/survival rates in the pre-reproductive period of development were studied. Based on these indicators, the selection indices were calculated according to the Crow`s formula. Results. In terms of individual components of fitness, such as egg production of females, the number of adult offspring, embryonic and pupal mortality, the spring and autumn populations of Gaidary did not show significant differences. Selection indices (Itot) in the autumn population of Gaidary were higher than in the spring population: in the embryonic period of development – by 50.4%, in the postembryonic period – by 67.5%. Differences in the intensity of selection are due to the variance of fertility, which was higher in the autumn population. Conclusions. Seasonal changes in the intensity of selection in different periods of ontogenesis are cumulative, which leads to increased selection pressure in the population of Gaidary in the autumn compared to spring. 
Keywords: Drosophila melanogaster Meig., natural population, fecundity, embryonic mortality, pupal mortality, Crow’s indices.