Disequilibrium due to linkage in self-fertilized populations

Abstract

Disequilibrium due to linkage in self-fertilized populations with selection forces has been investigated with respect to two genes. Two measures of disequilibrium have been used. One is the determinant of the matrix of the gametic frequencies and the other is the difference in the frequencies of coupling and repulsion heterozygotes. Based on some models, numerical solutions for the approach to equilibrium under linkage and selection have been obtained. It has been found that the equilibrium values of the two measures of disequilibrium do not become zero in all cases. The rate of approach to equilibrium is found to be dependent on the intensity of linkage, tight linkage prolonging the approach to equilibrium. Although coupling and repulsion heterozygotes become equally numerous in the population, it is possible that the equilibrium value of ‘d’ need not be zero in epistatic models. Differences in fitnesses between the coupling and repulsion heterozygotes quicken attainment of equilibrium when the homozygotes as well as single heterozygotes have equal fitnesses.