Selection parameters in lines of Drosophila melanogaster Meig., obtained from populations living in territories with different levels of radiation pollution: approbation of the Crow’s method

Abstract

Man-made disasters, such as the accidents at the Chornobyl NPP and the Fukushima NPP-1, have raised questions about the radiation risks associated with the use of atomic energy in a new and acute way. The purpose of the study was to investigate the features of the action of natural selection in the lines of Drosophila melanogaster Meig., obtained from natural populations living in territories with different levels of radiation pollution. One of the aims was to test Crow's method on a model object, such as Drosophila. This method makes it possible to estimate the total intensity of selection, as well as to determine the contribution of its individual components, such as differential fecundity and differential mortality. The study was carried out on three lines of Drosophila melanogaster Meig.: the Haidary line (radiation background in the territory from which the line originates: 0.12 μSv/h, β-radiation flux: 0 particles/cm2/min), the KhPTI line (radiation background: 0.12–0.20 μSv/h, β-radiation flux: 0 particles/cm2/min), the Chornobyl line (radiation background: 0.20–0.22 μSv/h, β-radiation flux: 7–8 particles/cm2/min). According to the obtained results, the lines did not differ among themselves in egg production of females. In terms of the number of adult offspring, the Chornobyl line was inferior to the Haidary and KhPTI lines by 48.9% and 57.8%, respectively. Mortality in the pre-reproductive period of development (indicator pd), which includes embryonic and pupal mortality, was the highest in the Chornobyl line and exceeded the pd value in the Haidary and KhPTI lines by 1.4 times. As a result, the Chornobyl line, obtained from the territory contaminated with radionuclides, significantly exceeded the Haidary and KhPTI lines, obtained from the territories where the radiation situation does not go beyond the norm, by both components of selection – both by the component of differential fecundity (If), and by differential mortality (lm). The total selection indices (Itot) were quite close in the Haidary and KhPTI lines, and in the Chornobyl line this index was 2,1–2,6 times higher than in the other two lines. The results of the study support the view that ionizing radiation can promote evolution by accelerating evolutionary change. They indicate an increased mortality rate, a reduced level of fitness and an increased selection pressure in the line of fruit flies, which originates from the population living in the radiation-contaminated territory in the Chornobyl exclusion zone.

Keywords

• γ-radiation, β-radiation, fecundity, embryonic mortality, pupal mortality, selection indices