Models of Natural Selection
Darwin’s theory of evolution by natural selection has had such an immense success in explaining the historical changes that have occurred in life on earth that it has come to be regarded by many people as the model for the dynamics of all historical processes. “Evolutionary change” has become identified as identical with “change by natural selection,” although there exist, in fact, two quite different modes of explanation for the evolution of systems in time. In the variational mode, which is characteristic of Darwinism, there is variation among the individual units comprising the whole system. The system changes in time by a change in the proportions of the different kinds of units, as a consequence of the differential survival and reproduction of the units. It is interesting that the only natural system known with certainty to evolve by this variational-selectional mode is the biological diversity of species.
KeywordsNatural Selection Gene Frequency Assortative Mating Selection Coefficient Phenotypic Space
Unable to display preview. Download preview PDF.
- Franklin, I. and R.C. Lewontin. 1970. Is the gene the unit of selection? Genetics 65: 707–734.Google Scholar
- Lewontin, R.C. 1964. The interaction of selection and linkage. II. Optimum models. Genetics 50: 757–782.Google Scholar
- Lewontin, R.C. 1966. Is nature probable or capricious? Bioscience JL6: 25–27.Google Scholar