[Selected plateau during long-term selection in experimental populations of Drosophila]

Drosophila subpopulations which did not any more response to the artificial selection effect were obtained as the result of long-term selection for the number of abdominal bristles and thorax length. Study on selection lines has shown that genetic variability may both decrease in the process of selection and increase temporarily. Not always does fixation of alleles controlling a quantitative character occur when the selection limits are achieved.