Data from: Genetic monitoring reveals temporal stability over 30 years in a small, lake resident brown trout population

Knowledge of the degree of temporal stability of population genetic structure and composition is important for understanding microevolutionary processes and for addressing issues on human impact on natural populations. We know little about how representative single samples in time are to reflect population genetic constitution. We explore the temporal genetic variability patterns over a 30-year period of annual sampling of a lake resident brown trout (Salmo trutta) population, covering 37 consecutive cohorts and five generations. Levels of variation remain largely stable over this period with no indication of substructuring within the lake. We detect genetic drift, however, and the genetically effective population size (Ne) was assessed from allele frequency shifts between consecutive cohorts using an unbiased estimator that accounts for the effect of overlapping generation. The overall mean Ne is estimated as 74. We find indications that Ne varies over time, but th ere is no obvious temporal trend. We also estimated Ne using a one-sample approach based on linkage disequilibrium (LD) not accounting for the effect of overlapping generations. Combining one-sample estimates for all years gives an Ne estimate of 76. This similarity between estimates may be coincidental or reflecting a general robustness of the LD approach to violations of the discrete generations assumption. In contrast to the observed genetic stability, body size and catch per effort have increased over the study period. Estimates of annual effective number of breeders (Nb) correlated with catch per effort suggesting that genetic monitoring can be used for detecting fluctuations in abundance.

解析种群遗传结构与组成的时间稳定性程度，对于理解微进化过程以及厘清人类活动对自然种群的影响具有重要意义。目前学界对单一时间点采样在反映种群遗传组成方面的代表性程度仍缺乏充分认知。本研究对湖泊栖息型褐鳟（Salmo trutta）种群开展了长达30年的年度采样，覆盖37个连续龄组与5个世代，借此剖析其遗传变异的时间分布模式。研究期间内，种群遗传变异水平整体保持稳定，未检测到该湖泊内存在种群亚结构。然而本研究检测到了遗传漂变现象，并采用考虑重叠世代效应的无偏估计量，基于连续龄组间的等位基因频率偏移，对遗传有效种群大小（genetically effective population size, Ne）进行了估算，整体平均Ne估算值为74。结果显示Ne随时间存在波动，但未呈现显著的时间趋势。本研究同时采用基于连锁不平衡（linkage disequilibrium, LD）的单样本方法估算Ne，但该方法未考虑重叠世代的影响。整合所有年度的单样本估算结果，得到的Ne估算值为76。两种估算结果的相似性或属偶然，亦或是连锁不平衡方法对违背离散世代假设的情形具有普遍稳健性的体现。与观测到的遗传稳定性形成鲜明对比的是，研究期间内褐鳟的个体体型与单位捕捞努力量渔获量均呈上升趋势。年度繁殖有效种群大小（effective number of breeders, Nb）的估算值与单位捕捞努力量渔获量呈显著相关，这表明遗传监测可用于检测种群丰度的波动情况。