Matías Luis, Gonzalez-Díaz Patricia, Quero José L, Camarero J Julio, Lloret Francisco, Jump Alistair S
Biological and Environmental Sciences, School of Natural Sciences, University of Stirling, Stirling FK9 4LA, UK
Present address: Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), PO Box 1052, 41080 Sevilla, Spain.
Tree Physiol. 2016 Oct;36(10):1236-1246. doi: 10.1093/treephys/tpw049. Epub 2016 Jun 6.
Changes in climate can alter the distribution and population dynamics of tree species by altering their recruitment patterns, especially at range edges. However, geographical patterns of genetic diversity could buffer the negative consequences of changing climate at rear range edges where populations might also harbour individuals with drought-adapted genotypes. Silver fir (Abies alba Mill.) reaches its south-western distribution limit in the Spanish Pyrenees, where recent climatic dieback events have disproportionately affected westernmost populations. We hypothesized that silver fir populations from the eastern Pyrenees are less vulnerable to the expected changing climate due to the inclusion of drought-resistant genotypes. We performed an experiment under strictly controlled conditions simulating projected warming and drought compared with current conditions and analysed physiology, growth and survival of silver fir seedlings collected from eastern and western Pyrenean populations. Genetic analyses separated eastern and western provenances in two different lineages. Climate treatments affected seedling morphology and survival of both lineages in an overall similar way: elevated drought diminished survival and induced a higher biomass allocation to roots. Increased temperature and drought provoked more negative stem water potentials and increased δC ratios in leaves. Warming reduced nitrogen concentration and increased soluble sugar content in leaves, whereas drought increased nitrogen concentration. Lineage affected these physiological parameters, with western seedlings being more sensitive to warming and drought increase in terms of δC, nitrogen and content of soluble sugars. Our results demonstrate that, in A. alba, differences in the physiological response of this species to drought are also associated with differences in biogeographical history.
气候变化可通过改变树种的更新模式来改变其分布和种群动态，尤其是在分布范围边缘。然而，遗传多样性的地理格局可能会缓冲气候变暖在分布范围后缘带来的负面影响，在这些区域，种群中可能也存在具有干旱适应基因型的个体。银杉（Abies alba Mill.）在西班牙比利牛斯山脉达到其西南分布极限，近期的气候衰退事件对最西部的种群造成了不成比例的影响。我们假设，由于包含抗旱基因型，来自比利牛斯山脉东部的银杉种群对预期的气候变化不太敏感。我们在严格控制的条件下进行了一项实验，将模拟预计的变暖和干旱与当前条件进行比较，并分析了从比利牛斯山脉东部和西部种群采集的银杉幼苗的生理、生长和存活情况。遗传分析将东部和西部种源分为两个不同的谱系。气候处理以总体相似的方式影响两个谱系的幼苗形态和存活：干旱加剧会降低存活率，并导致根系生物量分配增加。温度升高和干旱会引发更负的茎水势，并增加叶片中的δC比率。变暖会降低叶片中的氮浓度并增加可溶性糖含量，而干旱则会增加氮浓度。谱系会影响这些生理参数，就δC、氮和可溶性糖含量而言，西部幼苗对变暖和干旱加剧更为敏感。我们的结果表明，在银杉中，该物种对干旱的生理反应差异也与生物地理历史差异有关。
