Adaptation and Natural Selection

What follows from the Essence of Genetical Theory of Natural Selection

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Williams summarizes the essence of the genetical theory of natural selection as follows:

The essence of the genetical theory of natural selection is a statistical bias in the relative rates of survival of alternatives (genes, individuals, etc.). The effectiveness of such bias in producing adaptation is contingent on the maintenance of certain quantitative relationships among the operative factors. One necessary condition is that the selected entity must have a high degree of permanence and a low rate of endogenous change, relative to the degree of bias (differences in selection coefficients). Permanence implies reproduction with a potential geometric increase. (pp. 22-3, Uchii's italics).

This is an admirably succinct summary. The reader should try to understand thoroughly the implications of the italicized phrases. Otherwise, he/she will fail to grasp the reasoning leading to the following consequences:

(1) Certain kinds of selection become unimportant: phenotypes, individuals, genotypes are unimportant, and the "gene" must be the major object of selection. (But notice Williams' definition of "gene".)

(2) Natural selection would produce adaptation as a matter of definition. "A gene's mean phenotypic reproductive success" must be understood thoroughly. Why? Think yourself!

(3) "Necessity for survival" is not an evolutionary factor, and adaptation does not imply such necessity.

(4) The fact that a certain adaptation is necessary for survival has no bearing on the likelihood of evolving.

(5) Natural selection works only among competing entities, but ecological competition (for some limited resource) is not necessary.

(6) Natural selection does not imply any kind of progress.

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