IS SELECTION ALTERNATIVE OR COMPLEMENTARY TO VARIABILITY

This paper reviews the data demonstrating a large magnitude of variabi lity during long-term selection. The attention has been focused on the studies revealing preservation of genetic variability under condition s of intensive selection force. The data am discussed in terms of both classical genetic mechanisms to preserve variability and possible inf luence of selection on frequency of de novo arising changes. It is sup posed that the selection vector and the rate at which the changes occu r are interrelated. If selection acts mainly on phenotypes controlled by polygenes with regulatory functions, then its effect on variability is the highest. It is underlined that behavioral and physiological tr aits represent the phenotypes of such type.