Joint effects of mutation and selection on gametic frequencies in a panmictic population.

The classical theory of population genetics considers the situation when mutation rates are small relative to selection coefficients, and when selection acts only in previously mutated gametes and there is no back mutation. I have considered the effects of mutation and selection when the newly mutated gametes as well as the preexisting one are affected by selection. If the mutation rate m from A leads to a is greater than or equal to the selection coefficient, s, against a, the equilibrium frequency of A is zero. If m less than s, the equilibrium probability of A is m(1 - s)/s(1 - m). It is suggested that the solutions obtained here may be realistic in certain situations, particularly whey mutation is considered at the molecular level.