Human activity is a serious cause of huge changes in the environment and a constant reason for the emergence of new stress factors. Thus, to survive and reproduce, organisms must constantly implement a program of adaptation to continuously changing conditions. Presented here research are focused on tracking slow changes occurring in Spodoptera exigua (Lepidoptera: Noctuidae), that were caused by multigenerational exposure to sub- lethal cadmium doses. The insects received food containing cadmium at concentrations of 5, 11, 22 and 44 µg per g of dry mass of a food. The level of DNA stability was monitored by the Comet assay in subsequent generations, up to 36th generation. In the first three generations, the level of DNA damage was high, especially in the groups receiving higher doses of cadmium in the diet. In the fourth generation, a significant reduction in the level of DNA damage was observed, which could indicate that the desired stability of the genome was achieved. Surprisingly, however, in subsequent generations alternating increase and decrease of DNA stability was observed. The observed cycles of changing DNA stability were lasting longer in insects consuming food with a lower Cd content. Thus, a transient reduction in genome stability can be perceived as an opportunity to increase the number of variants which then undergo the selection. This phenomenon occurs faster if the severity of the stress factor is high, but low enough to allow the population to survive.

Professor, PhD, DSc Maria Augustyniak is working in the Institute of Biology, Biotechnology and Environmental Protection, University of Silesia in Katowice, Poland. Major scientific interests of professor Maria Augustyniak are: aging theory, stress theory and the theory of natural selection under anthropogenic pressure; ecotoxicology; assessment of DNA stability under the influence of various environmental stress factors, including nanoparticles. Results of her works are published in prestigious journals, including: Carbon, Journal of Hazardous Materials, Fish & Shellfish Immunology, Chemosphere, Environmental Research, Scientific Reports, Environmental Pollution and many others.