THE EVOLUTION OF DOMINANCE - A THEORY WHOSE TIME HAS PASSED

The evolution of dominance by the selection of modifiers of the phenot ypes of deleterious mutations was proposed as a hypothesis by R. A. Fi sher in 1928. It has been strongly criticized ever since, is regarded by many as having been made irrelevant by metabolic control theory, an d most recently has been claimed to have been 'falsified' by H. A. Orr . Is it indeed not only obsolete but wrong! Its history is reviewed an d its present status evaluated. We conclude (I) that it has a role as the explanation of the dominance found in many cases of selection thro ugh visual predation and (2) that the selection mechanism long claimed to be ineffective (the increase in frequency of a single modifier) wi ll be effective under certain special conditions that may be different from those Fisher proposed.