Data from: Temporal genetic stability in natural populations of the waterflea Daphnia magna in response to strong selection pressure

Studies monitoring changes in genetic diversity and composition through time allow a unique understanding of evolutionary dynamics and persistence of natural populations. However, such studies are often limited to species with short generation times that can be propagated in the laboratory or few exceptional cases in the wild. Species that produce dormant stages provide powerful models for the reconstruction of evolutionary dynamics in the natural environment. A remaining open question is to what extent dormant egg banks are an unbiased representation of populations and hence of the species’ evolutionary potential, especially in presence of strong environmental selection. We address this key question using the water flea Daphnia magna, which produces dormant stages that accumulate in biological archives over time. We assess temporal genetic stability in three biological archives, previously used in resurrection ecology studies showing adaptive evolutionary responses to rapid environmental change. We show that neutral genetic diversity does not decline with the age of the population and it is maintained in presence of strong selection. In addition, by comparing temporal genetic stability in hatched and unhatched populations from the same biological archive, we show that dormant egg banks can be consulted to obtain a reliable measure of genetic diversity over time, at least in the multi-decadal time frame studied here. The stability of neutral genetic diversity through time is likely mediated by the buffering effect of the resting egg bank.

通过长期追踪种群遗传多样性与遗传组成的动态变化，可获得对自然种群进化动力学及存续机制的独特认知。然而此类研究往往局限于可在实验室繁育的短世代物种，或是野外环境中极少数的特例。产生休眠体的物种，为重建自然环境中的进化动力学提供了极具价值的研究模型。目前尚存一个核心科学问题：休眠卵库（dormant egg banks）在多大程度上能够无偏地反映种群特征，进而反映物种的进化潜力？在强环境选择作用下这一问题尤为突出。本研究以大型溞（Daphnia magna）——该物种可产生休眠体并随时间在生物存档库中累积——来解答这一关键问题。我们选取此前用于复活生态学（resurrection ecology）研究的三份生物存档库，评估其种群的时间尺度遗传稳定性，这些存档库曾被用于揭示种群对快速环境变化的适应性进化响应。研究结果表明，中性遗传多样性（neutral genetic diversity）并不会随种群存续时长出现衰减，且在强选择压力下仍可得以维持。此外，通过对比同一份生物存档库中已孵化与未孵化种群的时间尺度遗传稳定性，本研究证实：至少在本次研究所覆盖的数十年时间跨度内，可借助休眠卵库可靠地反映种群随时间变化的遗传多样性水平。种群中性遗传多样性随时间保持稳定的现象，大概率是由休眠卵库的缓冲效应所介导的。