Microevolution of S-allele frequencies in wild cherry populations: respective impacts of negative frequency dependent selection and genetic drift

Negative frequency dependent selection (NFDS) is supposed to be the main force controlling allele evolution at the gametophytic self-incompatibility locus (S-locus) in strictly outcrossing species. Genetic drift also influences S-allele evolution. In perennial sessile organisms, evolution of allelic frequencies over two generations is mainly shaped by individual fecundities and spatial processes. Using wild cherry populations between two successive generations, we tested whether S-alleles evolved following NFDS qualitative and quantitative predictions. We showed that allelic variation was negatively correlated with parental allelic frequency as expected under NFDS. However, NFDS predictions in finite population failed to predict more than half all S-allele quantitative evolution. We developed a spatially-explicit mating model which included the S-locus. We studied the effects of self-incompatibility and local drift within populations due to pollen dispersal in spatially distributed indi...

负频率依赖选择（Negative frequency dependent selection, NFDS）被认为是严格异交物种中配子体自交不亲和位点（gametophytic self-incompatibility locus, S-locus）上等位基因进化的核心驱动力。遗传漂变（genetic drift）同样会对S等位基因的进化产生影响。对于多年生固着生物而言，两代间的等位基因频率进化主要由个体繁殖力与空间过程所塑造。本研究以两个连续世代的野生樱桃种群为研究对象，检验了S等位基因的进化是否契合负频率依赖选择的定性与定量预测范式。研究结果显示，等位基因变异与亲本等位基因频率呈负相关，这与负频率依赖选择理论的预期一致。然而，有限种群框架下的负频率依赖选择预测模型仅能解释不足半数的S等位基因定量进化过程。我们构建了包含S位点的空间显式交配模型，并探究了自交不亲和性以及空间分布个体间花粉扩散所引发的种群内局部漂变的效应……