Neutral additive genetic variance in a metapopulation

Abstract

For neutral, additive quantitative characters, the amount of additive genetic variance within and among populations is predictable from Wright's F_ST, the effective population size and the mutational variance. The structure of quantitative genetic variance in a subdivided metapopulation can be predicted from results from coalescent theory, thereby allowing single-locus results to predict quantitative genetic processes. The expected total amount of additive genetic variance in a metapopulation of diploid individual is given by 2N_eσ²_m (1 + F_ST), where F_ST is Wright's among-population fixation index, N_e is the eigenvalue effective size of the metapopulation, and σ²_m is the mutational variance. The expected additive genetic variance within populations is given by 2N_eσ²_e(1 − F_ST), and the variance among demes is given by 4F_STN_eσ²_m. These results are general with respect to the types of population structure involved. Furthermore, the dimensionless measure of the quantitative genetic variance among populations, Q_ST, is shown to be generally equal to F_ST for the neutral additive model. Thus, for all population structures, a value of Q_ST greater than F_ST for neutral loci is evidence for spatially divergent evolution by natural selection.