"An Empirical Evolutionary Generalization" Viewed from the Standpoint of Phenogenetics

Abstract

The paper discusses what G. G. Simpson has called an empirical evolutionary generalization, namely, an enhanced inter- and intra-individual variability of organs facing rudimentation. Comparable phenotypic features encountered in Drosophila mutants of low penetrance are discussed in terms of development involving time relations, points of determination, thresholds, and similar conceptions of physiological genetics. It is shown that simple mutants acting in a definite developmental system may account for the facts under discussion as well as for comparable ones of progressive evolution. The author warns against studying evolution exclusively from the standpoint of static genetics.