Data from: Climate-based seed transfer of a widespread shrub: population shifts, restoration strategies and the trailing edge

Genetic resources have to be managed appropriately to mitigate the impact of climate change. For many wildland plants, conservation will require knowledge of the climatic factors affecting intraspecific genetic variation to minimize maladaptation. Knowledge of the interaction between traits and climate can focus management resources on vulnerable populations, provide guidance for seed transfer and enhance fitness and resilience under changing climates. In this study, traits of big sagebrush (Artemisia tridentata) were examined among common gardens located in different climates. We focus on two subspecies, wyomingensis and tridentata, that occupy the most imperiled warm-dry spectrum of the sagebrush biome. Populations collected across the sagebrush biome were recorded for flower phenology and survival. Mixed-effects models examined each trait to evaluate genetic variation, environmental effects, and adaptive breadth of populations. Climate variables derived from population source locations were significantly associated with these traits (P < 0.0001), explaining 31% and 11% of the flower phenology and survival variation, respectively. To illustrate our model and assess variability in prediction, we examine fixed and focal point seed transfer approaches to map contemporary and climate model ensemble projections in two different regions of the sagebrush biome. A comparison of seed transfer areas predicts that populations from warmer climates become more prevalent, replacing colder-adapted populations by mid-century. However, these warm-adapted populations are often located along the trailing edge, margins of the species range predicted to be lost due to a contraction of the climatic niche. Management efforts should focus on the collection and conservation of vulnerable populations and prudent seed transfer to colder regions where these populations are projected to occur by mid-century. Our models provide the foundation to develop an empirical, climate-based seed transfer system for current and future restoration of big sagebrush.

为减缓气候变化带来的影响，需对遗传资源进行合理管理。针对多数野生植物而言，保育工作需掌握影响其种内遗传变异的气候因子，以最大限度降低适应不良风险。明晰性状与气候的互作关系，可将管理资源精准聚焦于脆弱种群，为种子调拨提供科学指导，并提升气候变化情境下种群的适合度与恢复力。本研究针对不同气候条件下的共同花园试验圃，对大盆地三齿蒿（Artemisia tridentata）的相关性状展开分析。研究聚焦于两个亚种：怀俄明亚种（wyomingensis）与原亚种（tridentata），它们分布于蒿灌丛生物群系中受威胁程度最高的暖干生境谱系。本研究记录了采集自整个蒿灌丛生物群系的种群的开花物候与存活率，并采用混合效应模型（Mixed-effects Models）分析各性状，以评估种群的遗传变异、环境效应及适应性广度。结果显示，源自种群来源地的气候变量与上述性状显著相关（P < 0.0001），分别解释了31%的开花物候变异与11%的存活率变异。为阐释本研究模型并评估预测变异性，本研究针对蒿灌丛生物群系的两个不同区域，分别采用固定种子调拨法与焦点种子调拨法，绘制当前气候及气候模型集合投影下的种子调拨区划。对种子调拨区域的对比分析显示，到本世纪中叶，源自温暖气候的种群将更为常见，并取代适应寒冷环境的种群。但这些适应温暖环境的种群通常分布于物种分布区的后缘地带，而该地带因气候生态位收缩，被预测将逐渐消失。相关管理工作应聚焦于脆弱种群的采集与保育，并审慎开展种子调拨，将其转移至本世纪中叶将适宜这些种群生存的寒冷区域。本研究构建的模型，可为当前及未来大盆地三齿蒿的修复工作提供基于气候的经验性种子调拨系统的研发基础。