caa a22 4500 386393028 CHVBK 20180307112126.0 cr unu---uuuuu 161130e198908 xx s 000 0 eng 10.1017/S0016672300028378 doi S0016672300028378 pii (NATIONALLICENCE)cambridge-10.1017/S0016672300028378 Barton Nick Department of Genetics and Biometry, University College London, 4 Stephenson Way, London NW1 2HE The divergence of a polygenic system subject to stabilizing selection, mutation and drift [Elektronische Daten] [Nick Barton] Polygenic variation can be maintained by a balance between mutation and stabilizing selection. When the alleles responsible for variation are rare, many classes of equilibria may be stable. The rate at which drift causes shifts between equilibria is investigated by integrating the gene frequency distribution W̅2NΠ(pq)4Nμ−1. This integral can be found exactly, by numerical integration, or can be approximated by assuming that the full distribution of allele frequencies is approximately Gaussian. These methods are checked against simulations. Over a wide range of population sizes, drift will keep the population near an equilibrium which minimizes the genetic variance and the deviation from the selective optimum. Shifts between equilibria in this class occur at an appreciable rate if the product of population size and selection on each locus is small (Nsα2 < 10). The Gaussian approximation is accurate even when the underlying distribution is strongly skewed. Reproductive isolation evolves as populations shift to new combinations of alleles: however, this process is slow, approaching the neutral rate (≈ μ) in small populations. Copyright © Cambridge University Press 1989 Genetical Research Cambridge University Press 54/1(1989-08), 59-78 0016-6723 54:1<59 1989 54 GRH https://doi.org/10.1017/S0016672300028378 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0016672300028378 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Barton Nick Department of Genetics and Biometry, University College London, 4 Stephenson Way, London NW1 2HE NATIONALLICENCE 773 0- Genetical Research Cambridge University Press 54/1(1989-08), 59-78 0016-6723 54:1<59 1989 54 GRH CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge