The role of major genes in the evolution of economic characters
The early ~lendelians devoted m~uok attention ~o the more ob,ious plant and animM characters, ,~nch as pigmenta/en, dwarfing and the like, and a wealth of information confirnfi~g Nendel's work was soon btdR up. The next stage--the ~pplieation of genetics to economic ends--disclosed di~ctdties, and experience has shown that many economic characters do not give simple i~leladelian ratios in hybriclization. As a resuR of this, modern thought tends more and more to stress the importance of .minor genes. This school of thought has been developed by Fisher (1%0) ~nd ~Stadent' (1933, 193~), and extended by Marker (19~.3c% b) with his polygene concept. The polygene school holds tit~t q~antitadve characters are normally b~ilt up by the Combined effect of a number of minor genes brought fiogether in response to s~lection pressure. A second school, led by the gu~siala academician Lysenko, maintains that the whole Nende!ian outlook is fallacious. Lysenko's (19~6) theobies, however, take so litde acconnt of established fact and scientific proof that for the pt~rposes of this paper they may safely be disregarded. Studies of the response of commercial cottons to blackarm* attack (Kmght & C]ous~on, 1939; ~:night, 19~r 1%6) have indicated that major genes are more important in the synthesis of resistant types than might have been supposed. From ttJs a theory has been developed, and is sat forth in this paper, of the significance of major genes in adaptive response.