Data from: Time to get moving: assisted gene flow of forest trees

Geographic variation in trees has been investigated since the mid-18th century. Similar patterns of clinal variation have been observed along latitudinal and elevational gradients in common garden experiments for many temperate and boreal species. These studies convinced forest managers that a ‘local is best’ seed source policy was usually safest for reforestation. In recent decades, experimental design, phenotyping methods, climatic data and statistical analyses have improved greatly and refined but not radically changed knowledge of clines. The maintenance of local adaptation despite high gene flow suggests selection for local adaptation to climate is strong. Concerns over maladaptation resulting from climate change have motivated many new genecological and population genomics studies; however, few jurisdictions have implemented assisted gene flow (AGF), the translocation of pre-adapted individuals to facilitate adaptation of planted forests to climate change. Here, we provide evidence that temperate tree species show clines along climatic gradients sufficiently similar for average patterns or climate models to guide AGF in the absence of species-specific knowledge. Composite provenancing of multiple seed sources can be used to increase diversity and buffer against future climate uncertainty. New knowledge will continue to refine and improve AGF as climates warm further.

自18世纪中叶以来，学界便已开展针对树木地理变异的研究。针对众多温带与寒带树种的同质园实验（common garden experiment）中，研究者已观测到沿纬度和海拔梯度呈现的相似渐变群变异（clinal variation）模式。上述研究使林业管理者确信，“本地种源最优”的种源政策通常是造林工作中最为稳妥的方案。近数十年来，实验设计、表型鉴定方法、气候数据及统计分析手段均得到大幅改进，虽未从根本上颠覆现有关于渐变群的认知，但对其进行了精细化完善。尽管存在高强度基因流，本地适应仍得以维持，这表明针对气候适配的本地适应选择压力极强。气候变化引发的适应不良问题引发学界担忧，由此催生了大量新的遗传生态学与群体基因组学研究；然而，仅有极少数地区推行了辅助基因流（assisted gene flow, AGF）——即通过移植预适应个体，助力人工林适应气候变化的实践。本研究证实，温带树种沿气候梯度呈现的渐变群模式具有足够的共性，即便缺乏针对特定物种的专属知识，也可依托通用模式或气候模型指导辅助基因流实践。采用多源种源复合配置策略，可提升种群多样性，有效缓冲未来气候不确定性带来的风险。随着气候持续变暖，相关研究的新进展将持续优化并完善辅助基因流的应用体系。