Variances and covariances of identity coefficients of a multigene family.

By using a model of gene conversion for treating concerted evolution of multigene families, a theory for calculating the variances and covariances of identity coefficients has been developed. Six coefficients on triple identity and 15 coefficients on quadruple identity are needed. The variances and covariances are obtained from the quadruple identity coefficients and divided into within-population and between-population components. The former represents the variation of identity coefficients among individuals within a population, whereas the latter represents the magnitude of fluctuation of population averages. Monte Carlo simulations confirmed the theoretical predictions at equilibrium.