Data from: Antagonistic versus non-antagonistic models of balancing selection: characterizing the relative timescales and hitchhiking effects of partial selective sweeps

Antagonistically selected alleles-–those with opposing fitness effects between sexes, environments, or fitness components-–represent an important component of additive genetic variance in fitness-related traits, with stably balanced polymorphisms often hypothesized to contribute to observed quantitative genetic variation. Balancing selection hypotheses imply that intermediate-frequency alleles disproportionately contribute to genetic variance of life-history traits and fitness. Such alleles may also associate with population genetic footprints of recent selection, including reduced genetic diversity and inflated linkage disequilibrium at linked, neutral sites. Here, we compare the evolutionary dynamics of different balancing selection models, and characterize the evolutionary timescale and hitchhiking effects of partial selective sweeps generated under antagonistic versus nonantagonistic (e.g., overdominant and frequency-dependent selection) processes. We show that the evolutionary timescales of partial sweeps tend to be much longer, and hitchhiking effects are drastically weaker, under scenarios of antagonistic selection. These results predict an interesting mismatch between molecular population genetic and quantitative genetic patterns of variation. Balanced, antagonistically selected alleles are expected to contribute more to additive genetic variance for fitness than alleles maintained by classic, nonantagonistic mechanisms. Nevertheless, classical mechanisms of balancing selection are much more likely to generate strong population genetic signatures of recent balancing selection.

拮抗选择等位基因（antagonistically selected alleles）——指在不同性别、环境或适合度组分间呈现相反适合度效应的等位基因——是适合度相关性状加性遗传方差的重要组成部分。学界普遍假设，稳定平衡多态性可对观测到的数量遗传变异做出重要贡献。平衡选择假说认为，中等频率等位基因会不成比例地参与生活史性状与适合度的遗传变异构成。此类等位基因还可能携带近期选择的种群遗传印记，具体表现为连锁中性位点处的遗传多样性降低与连锁不平衡（linkage disequilibrium）升高。本研究对比了不同平衡选择模型的进化动力学，并系统表征了拮抗选择与非拮抗选择（例如超显性（overdominant）、频率依赖选择）过程下产生的部分选择性清除的进化时间尺度与搭车效应（hitchhiking effects）。研究结果显示，在拮抗选择场景中，部分选择性清除的进化时间尺度普遍更长，且搭车效应也显著更弱。上述结果预示，分子种群遗传学与数量遗传学的变异模式间存在一处有趣的错配。相较于经典非拮抗机制维持的等位基因，平衡的拮抗选择等位基因预计会对适合度的加性遗传方差贡献更多。但与之矛盾的是，经典平衡选择机制反而更易产生显著的近期平衡选择种群遗传特征。