Hu Xin-Sheng, He Fangliang
Department of Renewable Resources, 751 General Services Building, University of Alberta, Edmonton, AB Canada T6G 2H1.
J Theor Biol. 2005 Jul 21;235(2):207-19. doi: 10.1016/j.jtbi.2005.01.004.
A general analytical formula is derived, which predicts the effects of background selection on population differentiation at a neutral locus as a result of its linkage with selected loci of deleterious mutations. The theory is based on the assumptions of random mating, multiplicative fitness, and weak selection in hermaphrodite plants in the island model of population structure. The analytical results show that Fst at the neutral locus increases as a result of the effects of background selection, regardless of the dependence or independence among linked background selective loci. The increment in Fst is closely related to the magnitude of linkage disequilibria between the neutral locus and selected loci, and can be estimated by the ratio of Fst with background selection to Fst without background selection minus one. The steady-state linkage disequilibrium between a neutral locus and a selected locus in subpopulations, primarily attained by gene flow, decreases with the recombination rate, and can be enhanced when there are dependence among linked selected loci. Monte Carlo computer simulations with two- and three-locus models show that the analytical formulae perform well under general conditions. Application of the present theory may aid in analyzing the genome-wide mapping of the effect of background selection in terms of Fst.
推导了一个通用分析公式,该公式预测了由于与有害突变的选择位点连锁,背景选择对中性位点群体分化的影响。该理论基于群体结构岛屿模型中雌雄同体植物随机交配、适合度相乘和弱选择的假设。分析结果表明,由于背景选择的影响,中性位点的Fst会增加,而与连锁背景选择位点之间的依赖性或独立性无关。Fst的增量与中性位点和选择位点之间的连锁不平衡程度密切相关,并且可以通过有背景选择时的Fst与无背景选择时的Fst之比减去1来估计。亚群体中中性位点和选择位点之间的稳态连锁不平衡主要通过基因流实现,它随重组率降低,并且当连锁选择位点之间存在依赖性时会增强。双位点和三位点模型的蒙特卡罗计算机模拟表明,这些分析公式在一般条件下表现良好。应用本理论可能有助于根据Fst分析全基因组范围内背景选择效应的图谱。