In plants, clonal propagation is a common reproductive strategy in parallel to sexual reproduction. It has both advantages and drawbacks, and the potential complete loss of sexual reproduction causes serious conservation concerns, especially because population maintenance then only relies on adult survival and low genetic diversity leads to decreased adaptive potential. We investigated the rare, southernmost populations of the mostly circumboreal twinflower Linnaea borealis, located in the Western Alps. Based on 105 AFLP markers and 118 leaf samples, including replicates, we estimated the genetic similarity threshold above which samples belong to a single clone. Although the species is known for extensive clonal propagation, we observed high genotypic diversity within the seven studied populations and almost all samples were genetically distinct. Nevertheless, some clonal samples were detected in two populations, separated by up to 180 m. We found a strong genetic differentiation among populations (overall Fst = 0.38), which was congruent with the previously documented high plastid diversity in the region. We therefore hypothesize that Alpine populations are relicts of the Quaternary glacial periods, when the species probably survived at these lower latitudes before colonizing Northern Europe. Regarding conservation, our results suggest that most extant plants result from sexual reproduction and that populations are not highly threatened. Nevertheless, since clones can be very long-lived and almost no seedlings were observed in recent years, events of sexual reproduction may be ancient. The current reproductive dynamics should therefore be studied to estimate e.g. pollinators activity, proportions of flowering plants, and seed set.

中文翻译：

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AFLP 标记显示在西阿尔卑斯山的稀有、最南端的 Linnaea borealis L. (Caprifoliaceae) 种群中克隆繁殖水平低，基因型多样性高

在植物中，克隆繁殖是与有性繁殖并行的常见繁殖策略。它既有优点也有缺点，有性生殖的潜在完全丧失引起了严重的保护问题，特别是因为种群维持仅依赖于成体生存，而低遗传多样性导致适应性潜力下降。我们调查了位于西阿尔卑斯山的稀有、最南端的双花双花 Linnaea borealis 种群。基于 105 个 AFLP 标记和 118 个叶样本，包括复制品，我们估计了遗传相似性阈值，高于该阈值的样本属于单个克隆。尽管该物种以广泛的克隆繁殖而闻名，但我们在七个研究种群中观察到了高基因型多样性，并且几乎所有样本在遗传上都是不同的。然而，在两个种群中检测到了一些克隆样本，间隔达 180 m。我们发现种群之间存在强烈的遗传差异（总体 Fst = 0.38），这与先前记录的该地区的高质体多样性一致。因此，我们假设高山种群是第四纪冰川时期的遗迹，当时该物种可能在殖民北欧之前在这些低纬度地区幸存下来。关于保护，我们的结果表明，大多数现存植物来自有性繁殖，种群并未受到高度威胁。尽管如此，由于克隆的寿命很长，而且近年来几乎没有观察到幼苗，因此有性繁殖事件可能是古老的。因此，应研究当前的繁殖动态以估计传粉媒介的活动，