Pleiotropy and the Evolution of Adaptability

Abstract

The systems approach to the investigation of organismic evolution is a conceptual framework introduced by Riedl in the 1970s (Riedl, 1977, 1978). One aim was to elucidate the relationship between certain evolutionary implications of morphological concepts, such as homology, and the population genetic approach of Modern Synthesis. At about the same time an intense scientific discussion began anew regarding the interpretation of macroevolution. Some scientists doubted the usefulness of the population genetic program to the area of macroevolution (Gould, 1980; Stanley, 1975). In fact, there are reasons in the mathematical structure of evolutionary theory: the formal apparatus of population genetics was created to describe elementary mechanisms of evolution, i.e. the distribution and change of gene frequencies, but not the process of evolution itself, i.e. the transformation of genotypic and phenotypic patterns of organization. Two statements, which at first glance seem to be incompatible, mark the positions in this discussion between microevolutionists and macroevolutionists: 1. There are no elementary mechanisms other than these offered by population genetics: mutation, duplication, selection, migration and random drift; every neo-Darwinian explanation must be based on these mechanisms. 2. Phenomena of macroevolution follow their own laws which cannot necessarily be derived from the principles of microevolution.