Summaries of Addresses of Presidents of Sections: Natural Selection and Evolutionary Progress

Abstract

HE subject of Prof. Julian S. Huxley's presi- dential address to Section D (Zoology) is the relationship of natural selection and evolution. On a Mendelian planet, such as ours appears to be, evolution is the joint product of mutation and natural selection. Recent work has altered our views as to the details of the process. The action of a particular gene depends on many other genes which act as modifiers; thus selection of the genie background is of great importance. By this means, deleterious effects of an otherwise advantageous mutation can be buffered or even abolished. Dominance and recessivity seem to be due to a similar action on recurrent mutations.