Data from: Centromere–associated meiotic drive and female fitness variation in Mimulus

Female meiotic drive, in which chromosomal variants preferentially segregate to the egg pole during asymmetric female meiosis, is a theoretically pervasive but still mysterious form of selfish evolution. Like other selfish genetic elements, driving chromosomes may be maintained as balanced polymorphisms by pleiotropic or linked fitness costs. A centromere-associated driver (D) with a ∼58:42 female-specific transmission advantage occurs at intermediate frequency (32-40%) in the Iron Mountain population of the yellow monkeyflower, Mimulus guttatus. Previously determined male fertility costs are sufficient to prevent the fixation of D, but predict a higher equilibrium frequency. To better understand the dynamics and effects of D, we developed a new population genetic model and measured genotype-specific lifetime female fitness in the wild. In three of four years, and across all years, D imposed significant recessive seedset costs, most likely due to hitchhiking by deleterious mutations. With both male and female costs as measured, and 58:42 drive, our model predicts an equilibrium frequency of D (38%) very close to the observed value. Thus, D represents a rare selfish genetic element whose local population genetic dynamics have been fully parameterized, and the observation of equilibrium sets the stage for investigations of co-evolution with suppressors.

雌性减数分裂驱动（female meiotic drive）指在不对称雌性减数分裂过程中，染色体变异体优先向卵极分离，是一种理论上广泛存在但至今仍未被完全阐明的自私进化形式。与其他自私遗传元件（selfish genetic elements）类似，驱动染色体可通过多效性或连锁的适合度代价维持为平衡多态性。一种与着丝粒关联的驱动因子（centromere-associated driver，代号D）具有约58:42的雌性特异性传递优势，在黄色猴面花（Mimulus guttatus）的Iron Mountain种群中以中等频率（32%~40%）存在。此前已确定的雄性育性代价足以阻止D的固定，但预测的平衡频率更高。为更深入解析D的群体动态与效应，我们构建了全新的群体遗传学模型，并在野外环境中测定了基因型特异性的终身雌性适合度。在四年中的三年以及所有年份的合并分析中，D均带来了显著的隐性结籽代价，这一效应极有可能源于有害突变的遗传搭便车（hitchhiking）效应。结合实测的雄性与雌性适合度代价，以及58:42的驱动比例，我们的模型预测D的平衡频率为38%，与观测值极为接近。综上，D是一种罕见的自私遗传元件，其局部群体遗传动态已被完全参数化；而这一平衡频率的观测结果，为后续开展抑制子协同进化相关研究奠定了基础。