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We studied the influence of parental age on the degree of polyteny of giant chromosomes and expressivity of mutation eyeless in Drosophila melanogaster descendants. The parental age equal to six days exerted an adverse effect on the function of endoreduplication of giant chromosomes in strain eyeless. The highest degree of polyteny was observed in descendants of four- and ten-day imago. The maximum reduction of eye facets was observed in descendants of four-day imago, while in the progeny of older parents, the mutation expressivity was sharply reduced. Relations between the changes in chromosome polyteny, expressivity of mutation eyeless, and earlier studied components of adaptation were statistically analyzed in descendants of aging parents of this Drosophila strain.

We studied the effect of parental age on expressivity of trait eyeless, fertility, heat resistance, and life span of Drosophila offspring. We found that these characteristics show different changes in the offspring of aging parents. The ontogenetic curve of changes of expressivity of the trait eyeless and fertility is similar to the curve of normal distribution. As concerns the changes in heat resistance, they are complex in nature: the offspring of "young" or "old" parents has the highest heat resistance. Age of parents in the studied range does not significantly affect the mean life span of the offspring.