Future climate change has been predicted to disrupt local adaptation in many perennial plants, such as forest trees, but the magnitude and location of these effects are thus far poorly understood. Here, we assess local adaptation to current climate in European aspen (Populus tremula) by using environmental association analyses to identify genetic variants associated with two representative climate variables describing current day variation in temperature and precipitation. We also analysed patterns of genetic differentiation between southern and northern populations and observe that regions of high genetic differentiation are enriched for SNPs that are significantly associated with climate. Using variants associated with climate, we examined patterns of isolation by distance and environment and used spatial modelling to predict the geographic distribution of genomic variation in response to two scenarios of future climate change. We show that climate conditions at a northern reference site will correspond to climate conditions experienced by current day populations located 4–8 latitude degrees further south. By assessing the relationship between phenotypic traits and vegetative fitness, we also demonstrate that southern populations harbour genetic variation that likely would be adaptive further north under both climate change scenarios. Current day populations at the lagging edge of the distribution in Sweden can therefore serve as sources for introducing adaptive alleles onto northern populations, but the likelihood of this largely depends on naturally occurring levels of gene flow.

中文翻译：

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当前和未来气候条件下欧洲白杨（欧洲山杨）环境适应的全基因组特征。

据预测，未来的气候变化将破坏许多多年生植物（例如林木）的局部适应能力，但迄今为止，人们对这些影响的程度和位置知之甚少。在这里，我们通过使用环境关联分析来识别与描述当前温度和降水变化的两个代表性气候变量相关的遗传变异，从而评估欧洲白杨（欧洲山杨）对当前气候的局部适应。我们还分析了南部和北部种群之间的遗传分化模式，并观察到遗传分化高的区域富含与气候显着相关的 SNP。利用与气候相关的变异，我们检查了距离和环境的隔离模式，并使用空间模型来预测基因组变异的地理分布，以应对未来气候变化的两种情景。我们表明，北部参考地点的气候条件将与位于更南纬 4-8 度的当今人口所经历的气候条件相对应。通过评估表型性状和植物适应性之间的关系，我们还证明，南方种群具有遗传变异，在两种气候变化情景下，这些变异可能会适应更北的地区。因此，目前瑞典分布落后边缘的种群可以作为将适应性等位基因引入北方种群的来源，但这在很大程度上取决于自然发生的基因流水平。