Data from: Establishment and maintenance of adaptive genetic divergence under migration, selection, and drift

There is a long tradition in population genetics of exploring the maintenance of variation under migration-selection balance using deterministic models that assume infinite population size. With finite population size, stochastic dynamics can greatly reduce the potential for the maintenance of polymorphism, but this has yet to be explored in detail. Here, classical two-patch models are extended to predict: i) the probability of a locally beneficial mutation rising in frequency in the patch where it is favored, and ii) the critical threshold migration rate above which the maintenance of polymorphism is much less likely. Individual-based simulations show that these approximations provide accurate predictions across a wide range of parameter space.

种群遗传学（population genetics）领域有着悠久的研究传统：即借助假设种群规模无限的确定性模型（deterministic models），探究迁移-选择平衡（migration-selection balance）下遗传变异的维持机制。当种群规模有限时，随机动力学（stochastic dynamics）过程可大幅削弱多态性（polymorphism）得以维持的可能性，但该问题尚未得到详尽的研究。本研究对经典两斑块模型（two-patch models）进行拓展，用以预测两项核心内容：其一，局部有益突变（locally beneficial mutation）在其受选择青睐的斑块中频率上升的概率；其二，多态性维持可能性显著降低的临界迁移率阈值（critical threshold migration rate）。基于个体的模拟（individual-based simulations）结果表明，上述近似模型能够在广泛的参数空间（parameter space）内给出精准的预测结果。