Abstract
SummaryPolygenic 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 distributionW̅2NΠ(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.
Subject
Genetics,General Medicine
Reference36 articles.
1. The roles of mutation, inbreeding, crossbreeding and selection in evolution;Wright;Proceedings of the Sixth International Congress of Genetics,1932
2. Turelli M. & Barton N. H. (1989). Dynamics of polygenic characters under selection. Manuscript submitted to Genetics.
3. Frequency- and density-dependent selection on a quantitative character;Slatkin;Genetics,1979
4. The isolation of polygenic factors controlling bristle score in Drosophila melanogaster. II. Distribution of the third chromosome bristle effects on chromosome sections;Shrimpton;Genetics,1988
5. Speciation and the “shifting balance” in a continuous population
Cited by
78 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献