Data from: Genetic change for earlier migration timing in a population of pink salmon

To predict how climate change will influence populations it is necessary to understand the mechanisms, particularly microevolution and phenotypic plasticity, which allow populations to persist in novel environmental conditions. Although evidence for climate-induced phenotypic change in populations is widespread, evidence documenting that these phenotypic changes are due to microevolution is exceedingly rare. In this study we use 32 years of genetic data (17 complete generations) to determine whether there has been genetic change toward earlier migration timing in a population of pink salmon that shows phenotypic change; average migration time occurs nearly 2 weeks earlier than it did 40 years ago. Experimental genetic data support the hypothesis that there has been directional selection for earlier migration timing, resulting in a substantial decrease in the late migrating phenotype (from >30% to <10% of the total abundance). From 1983-2011 there was a significant decrease – over three fold – in the frequency of a genetic marker for late migration timing, but there were minimal changes in allele frequencies at other neutral loci. These results demonstrate there has been rapid microevolution for earlier migration timing in this population. Circadian rhythm genes, however, did not show any evidence for selective changes from 1993-2009.要预测气候变化将如何影响种群，就必须阐明使种群能够在新环境中存续的相关机制，尤其是微进化（microevolution）与表型可塑性（phenotypic plasticity）。尽管种群中由气候诱导产生表型变化的证据已较为普遍，但能证明这些表型变化源于微进化的相关证据却极为稀缺。本研究依托32年的遗传数据（涵盖17个完整世代），针对出现表型变化的粉红鲑鱼（pink salmon）种群，探究其洄游时间是否已发生遗传层面的提前：当前种群的平均洄游时间较40年前提前了近两周。实验遗传数据支持如下假说：该种群已发生针对更早洄游时间的定向选择，导致晚洄游表型的占比大幅下降（从总种群占比的30%以上降至10%以下）。1983年至2011年间，晚洄游相关遗传标记的频率出现了超过三倍的显著下降，但其他中性基因座的等位基因频率仅发生了极小变化。上述结果表明，该种群的洄游时间已发生快速的微进化。不过，1993年至2009年间的昼夜节律基因（circadian rhythm genes）并未表现出任何选择性变化的迹象。