A General Population Genetic Framework for Antagonistic Selection That Accounts for Demography and Recurrent Mutation
A General Population Genetic Framework for Antagonistic Selection That Accounts for Demography and Recurrent Mutation
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DOI：
10.1534/genetics.111.137117
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发表时间：
2012-04-01
期刊：
影响因子：
3.3
通讯作者：
Clark, Andrew G.
中科院分区：
文献类型：
--
作者：
Connallon, Tim;Clark, Andrew G.
对抗性选择——一个基因座上的等位基因对雄性和雌性的适合度有相反的影响（“性对抗”），或在适合度的组成部分之间有相反的影响（“对抗性多效性”）——可能在维持种群遗传变异、驱动两性二态性和生活史进化的系统发育和基因组模式方面发挥重要作用。虽然先前的理论已经彻底地描述了对抗性平衡选择运作的必要条件，但我们目前对对抗性选择、反复突变和遗传漂变之间的进化相互作用知之甚少，而这些相互作用应该共同形成遗传变异的经验模式。为了填补这一空白，我们开发并分析了一系列同时包含这些过程的群体遗传模型。我们的模型确定了拮抗选择位点的两个一般特性。首先，拮抗选择扩大了广泛参数范围内的杂合度和适合度方差——这一结果适用于通过平衡选择和反复突变维持的等位基因。其次，有效群体大小和遗传漂变对拮抗选择等位基因的统计频率分布有深刻影响。相对于定向选择和显性选择等经典模式，拮抗选择的“功效”（即其倾向于支配遗传漂变）是极其微弱的。然而，满足传统强选择标准的等位基因(N（e)s >> 1，其中N(e)为有效种群大小，s为给定性别或适合度成分的选择系数）可能会像中性一样进化。突变和人口统计学的影响可能导致种群间拮抗适应度变异总体水平的差异，以及平衡选择的分子群体遗传特征。
Antagonistic selection-where alleles at a locus have opposing effects on male and female fitness ("sexual antagonism") or between components of fitness ("antagonistic pleiotropy")-might play an important role in maintaining population genetic variation and in driving phylogenetic and genomic patterns of sexual dimorphism and life-history evolution. While prior theory has thoroughly characterized the conditions necessary for antagonistic balancing selection to operate, we currently know little about the evolutionary interactions between antagonistic selection, recurrent mutation, and genetic drift, which should collectively shape empirical patterns of genetic variation. To fill this void, we developed and analyzed a series of population genetic models that simultaneously incorporate these processes. Our models identify two general properties of antagonistically selected loci. First, antagonistic selection inflates heterozygosity and fitness variance across a broad parameter range-a result that applies to alleles maintained by balancing selection and by recurrent mutation. Second, effective population size and genetic drift profoundly affect the statistical frequency distributions of antagonistically selected alleles. The "efficacy" of antagonistic selection (i.e., its tendency to dominate over genetic drift) is extremely weak relative to classical models, such as directional selection and overdominance. Alleles meeting traditional criteria for strong selection (N(e)s >> 1, where N-e is the effective population size, and s is a selection coefficient for a given sex or fitness component) may nevertheless evolve as if neutral. The effects of mutation and demography may generate population differences in overall levels of antagonistic fitness variation, as well as molecular population genetic signatures of balancing selection.