Swiss Federal Institute for Forest, Snow and Landscape Research, WSL, CH-8903, Birmensdorf, Switzerland.
Department of Forest Ecosystems and Society, Oregon State University, 321 Richardson Hall, Corvallis, Oregon, 97331-5752, USA.
Ecology. 2017 Jan;98(1):211-227. doi: 10.1002/ecy.1632.
Understanding the genecology of forest trees is critical for gene conservation, for predicting the effects of climate change and climate change adaptation, and for successful reforestation. Although common genecological patterns have emerged, species-specific details are also important. Which species are most vulnerable to climate change? Which are the most important adaptive traits and environmental drivers of natural selection? Even though species have been classified as adaptive specialists vs. adaptive generalists, large-scale studies comparing different species in the same experiment are rare. We studied the genecology of Norway spruce (Picea abies) and silver fir (Abies alba), two co-occurring but ecologically distinct European conifers in Central Europe. For each species, we collected seed from more than 90 populations across Switzerland, established a seedling common-garden test, and developed genecological models that associate population variation in seedling growth and phenology to climate, soil properties, and site water balance. Population differentiation and associations between seedling traits and environmental variables were much stronger for Norway spruce than for silver fir, and stronger for seedling height growth than for bud phenology. In Norway spruce, height growth and second flushing were strongly associated with temperature and elevation, with seedlings from the lowlands being taller and more prone to second flush than seedlings from the Alps. In silver fir, height growth was more weakly associated with temperature and elevation, but also associated with water availability. Soil characteristics explained little population variation in both species. We conclude that Norway spruce has become an adaptive specialist because trade-offs between rapid juvenile growth and frost avoidance have subjected it to strong diversifying natural selection based on temperature. In contrast, because silver fir has a more conservative growth habit, it has evolved to become an adaptive generalist. This study demonstrates that co-occurring tree species can develop very different adaptive strategies under identical environmental conditions, and suggests that Norway spruce might be more vulnerable to future maladaptation due to rapid climate change than silver fir.
了解森林树木的遗传学对于基因保护、预测气候变化和气候变化适应以及成功的重新造林至关重要。尽管已经出现了常见的遗传模式，但物种特异性的细节也很重要。哪些物种最容易受到气候变化的影响？哪些是自然选择的最重要适应特征和环境驱动因素？尽管已经将物种分类为适应性专家与适应性通才，但在相同实验中比较不同物种的大规模研究仍然很少。我们研究了挪威云杉（Picea abies）和银冷杉（Abies alba）这两种在中欧共同存在但生态特征不同的欧洲针叶树的遗传学。对于每种物种，我们从瑞士的 90 多个种群中采集种子，建立了幼苗共同花园试验，并开发了将种群内幼苗生长和物候变化与气候、土壤特性和站点水分平衡相关联的遗传模型。与银冷杉相比，挪威云杉的种群分化和幼苗特征与环境变量之间的关联要强得多，而且幼苗高度生长与芽物候之间的关联要强得多。在挪威云杉中，高度生长和第二次萌芽与温度和海拔高度密切相关，低地的幼苗比阿尔卑斯山的幼苗更高，更容易第二次萌芽。在银冷杉中，高度生长与温度和海拔的相关性较弱，但也与水分可用性有关。土壤特征在两个物种中都只能解释很小的种群变异。我们得出的结论是，挪威云杉已经成为一种适应性专家，因为快速幼年生长和避免霜冻之间的权衡使它受到基于温度的强烈多样化自然选择的影响。相比之下，由于银冷杉的生长习性较为保守，它已经进化成为一种适应性通才。本研究表明，在相同的环境条件下，共存的树种可以发展出非常不同的适应策略，并表明由于快速气候变化，挪威云杉可能比银冷杉更容易受到未来适应不良的影响。
