Effects of cyclic changes in population size on neutral genetic diversity

Recurrent changes in population size are often observed in nature, influencing the efficiency of selection and consequently affecting organismal evolution. Thus, it is important to know whether such changes occurred in the past history of a focal population of evolutionary interests. Here, we focused on cyclic changes in population size and investigated the distributional properties of Tajima’s D and its power to distinguish a cyclic change model compared with the standard neutral model, changing the frequency and magnitude of the cyclic change. With very low or very high frequencies of the cycle, the distribution of Tajima’s D was similar to that in a constant-size population, as demonstrated by previous theoretical works. Otherwise, its mean was negative or positive, and its variance was smaller or larger depending on the time of sampling. The detection rate of the cyclic change against the constancy in size by Tajima’s D depended on the sample size, the number of loci and the time of...

自然界中常可观测到种群规模的反复变化，这类波动会影响选择效率，进而对生物演化进程产生影响。因此，明确具有演化研究价值的目标种群的历史是否经历过此类变化，具有重要意义。本研究聚焦于种群规模的周期性波动，通过调整周期的发生频率与波动幅度，探究塔伊马D统计量（Tajima's D）的分布特征，以及其区分周期性波动模型与标准中性模型的检测效能。正如此前的理论研究所证实的那样，当周期发生频率极低或极高时，塔伊马D统计量的分布与种群规模恒定的情形下的分布较为相似。而在其他频率区间内，其均值会呈现正负之分，方差的大小则取决于采样时点。利用塔伊马D统计量检测种群规模周期性波动（相较于规模恒定）的检出率，取决于样本量、基因座数量以及采样时点……