Data from: High genetic variation in resting stage production in a metapopulation: is there evidence for local adaptation?

Local adaptation is a key process for the maintenance of genetic diversity and population diversification. A better understanding of the mechanisms that allow (or prevent) local adaptation constitutes a key in apprehending how and at what spatial scale it occurs. The production of resting stages is found in many taxa and reflects an adaptation to outlast adverse environmental conditions. Daphnia magna (Crustacea) can alternate between asexual and sexual reproduction, the latter being linked to dormancy, as resting stages can only be produced sexually. In this species, on a continental scale, resting stage production is locally adapted, i.e. it is induced when the photoperiod indicates the imminence of habitat deterioration. Here, we aimed to explore whether selection is strong enough to maintain local adaptation at a scale of a few kilometers. We assessed life history traits of 64 D. magna clones originating from 11 populations of a meta-population with permanent and intermittent pool habitats. We found large within- and between-population variation for all dormancy-related traits, but no evidence for the hypothesised higher resting stage production in animals from intermittent habitats. We discuss how gene flow, founder events or other forms of selection might interfere with the process of local adaptation.

本地适应（local adaptation）是维持遗传多样性与种群分化的核心过程。深入阐明介导或抑制本地适应的机制，是理解其发生方式与空间尺度的关键所在。诸多类群均能产生休眠阶段（resting stages），这一特征是其适应恶劣环境以延续生存的体现。大型溞（Daphnia magna，甲壳纲Crustacea）可在无性生殖与有性生殖之间切换，其中有性生殖与休眠相关，因为休眠阶段仅能通过有性生殖产生。就该物种而言，在大陆尺度下，其休眠阶段的产生已发生本地适应，即当光周期（photoperiod）预示生境即将退化时，该过程会被诱导启动。本研究旨在探究：在数千米的空间尺度下，选择压力是否足够强，足以维持本地适应。我们对源自11个集合种群（meta-population）的64个大型溞克隆（clones）的生活史性状（life history traits）进行了测定，这些种群分别栖息于永久性与间歇性水塘生境中。结果显示，所有与休眠相关的性状均存在显著的种群内与种群间变异，但未发现支持“间歇性水塘生境中的个体具有更高休眠阶段产生率”这一假说的证据。我们还讨论了基因流（gene flow）、奠基者事件（founder events）及其他形式的选择可能如何干扰本地适应的过程。