ИСТИНА

The ability of laboratory populations of Drosophila melanogaster for selection-induced rapid changes makes this species a convenient object for experimental evolution studies. Since 2014, we rear experimental outbred lines of wild-type flies on either standard growth medium or one of the two unfavourable media: nutrient-deficient starch-based and high-salt media. Currently, our research goals fell into four categories. (1) Changes in fitness in the course of adaptation in homogeneous vs. spatially heterogeneous conditions. We found that adaptation to stressful high-salt medium results in higher fitness on both standard and high-salt media, and that spatial heterogeneity (wherein flies can choose between two unfavorable media) facilitates generalization and better adaptation compared to homogenous conditions. (2) We investigate the contribution of symbiotic microbiome to adaptation of flies to stressful media. We found that particular strains of symbiotic yeast improve flies’ survival and reproduction efficiency on high-salt medium. (3) We checked the hypothesis that positive assortative mating can arise rapidly in Drosophila laboratory populations reared in different stressful conditions. We showed that nonrandom mating arose in some, but not all lines, and that positive assortative mating in multiple-choice tests can arise from differences in general mating propensity between the lines rather than from true preference for similar mates. (4) The ‘gerontological’ part of the experiment is dedicated to the evolution of ageing. We found that adaptation to unfavourable diets can affect longevity and ageing, partially in line with Williams’ idea of antagonistic pleiotropy. Besides, we select flies for late-age reproduction and monitor changes in their lifespan and fecundity.