The Alpine landscape is characterized by high spatiotemporal heterogeneity in environmental variables, such as climate and soil characteristics. This may lead to divergent selection pressures across plant populations and to local adaptation. Geum reptans, a widespread high-alpine clonal herb, has been the subject of several studies investigating phenotypic variation in populations across the Swiss Alps, yet so far, there is only little knowledge about local adaptation in this species from reciprocal transplantations across original field sites. Here, we reciprocally transplanted three populations of Geum reptans in the Central Swiss Alps, growing at close or far geographical distance from each other, and compared growth- and reproduction-related traits to investigate patterns of local adaptation. We further measured leaf morphological traits to assess potential selection at field sites, and quantified the relative importance of genetic vs. environmental variation (i.e., phenotypic plasticity) for all traits. Additionally, among and within population genetic differentiation was analyzed using microsatellite markers. Molecular diversity was high within populations, and molecular differentiation increased with geographic distance among populations, suggesting that gene flow is maintained at close range, but decreased with distance. Although extensive phenotypic variation was found across site × population transplant combinations, our study revealed little evidence for local adaptation in G. reptans populations. Plant traits also showed strong plasticity, as revealed by pronounced site effects, yet no direct linear selection was detected on leaf trait values within field sites. We suggest that the glacier forelands studied here, which are representative of the habitat of large G. reptans populations, are too similar in environmental conditions to lead to among population intraspecific differentiation in line with local adaptation. As G. reptans showed a great capacity to respond plastically to environmental conditions, we cautiously advocate that the evolution of phenotypic plasticity might have prevailed over genetic differentiation for the adaptation to the relatively narrow niche of this species.

中文翻译：

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种内表型变异高，但在瑞士中部阿尔卑斯山的金缕梅种群中没有局部适应的证据

高山景观的特征是环境变量（如气候和土壤特征）的高度时空异质性。这可能导致整个植物种群的选择压力不同，并导致当地的适应。锦葵属植物，一种普遍存在的高高山克隆草本植物，已经成为调查瑞士阿尔卑斯山种群表型变异的几项研究的主题，但到目前为止，通过跨原始田间的相互移植，对该物种的局部适应性知之甚少。在这里，我们相互移植了三个种群的锦葵在瑞士中部阿尔卑斯山，彼此之间的地理距离相近或相距较远，并比较了与生长和繁殖相关的特征，以研究当地的适应方式。我们进一步测量了叶片形态特征，以评估田间地点的潜在选择，并量化了所有特征的遗传与环境变异（即表型可塑性）的相对重要性。另外，使用微卫星标记分析了群体间和群体内的遗传分化。种群内部的分子多样性很高，并且种群之间的分子分化随地理距离的增加而增加，这表明基因流保持在近距离，但随着距离的增加而降低。尽管在跨站点×群体移植组合中发现了广泛的表型变异，G. reptans种群。如明显的部位效应所揭示的那样，植物性状还表现出较强的可塑性，但在田间场所中未检测到对叶片性状值的直接线性选择。我们建议，这里研究的冰川前陆（代表大型rep。reptans种群的栖息地）在环境条件下过于相似，无法根据局部适应性导致种群内种间分化。由于瑞格氏菌显示出对环境条件具有塑性响应的强大能力，因此我们谨慎地主张表型可塑性的进化可能已经胜过遗传分化，以适应该物种相对狭窄的生态位。