School of Biological Sciences, University of Utah, Salt Lake City, UT, 84112, USA.
Wilkes Center for Climate Science and Policy, University of Utah, Salt Lake City, UT, 84112, USA.
New Phytol. 2023 Jul;239(1):174-188. doi: 10.1111/nph.18937. Epub 2023 May 2.
Intraspecific variation in functional traits may mediate tree species' drought resistance, yet whether trait variation is due to genotype (G), environment (E), or G×E interactions remains unknown. Understanding the drivers of intraspecific trait variation and whether variation mediates drought response can improve predictions of species' response to future drought. Using populations of quaking aspen spanning a climate gradient, we investigated intraspecific variation in functional traits in the field as well as the influence of G and E among propagules in a common garden. We also tested for trait-mediated trade-offs in growth and drought stress tolerance. We observed intraspecific trait variation among the populations, yet this variation did not necessarily translate to higher drought stress tolerance in hotter/drier populations. Additionally, plasticity in the common garden was low, especially in propagules derived from the hottest/driest population. We found no growth-drought stress tolerance trade-offs and few traits exhibited significant relationships with mortality in the natural populations, suggesting that intraspecific trait variation among the traits measured did not strongly mediate responses to drought stress. Our results highlight the limits of trait-mediated responses to drought stress and the complex G×E interactions that may underlie drought stress tolerance variation in forests in dry environments.
种内功能性状的变异可能介导树种的抗旱性，但性状变异是由于基因型 (G)、环境 (E) 还是 G×E 相互作用引起的，目前尚不清楚。了解种内性状变异的驱动因素以及变异是否介导干旱响应，可以提高对物种未来对干旱响应的预测能力。本研究利用跨越气候梯度的颤杨种群，在野外调查了功能性状的种内变异，以及在共同园中繁殖体之间的 G 和 E 的影响。我们还测试了生长和耐旱性之间是否存在性状介导的权衡。我们观察到种群之间存在种内性状变异，但这种变异并不一定意味着在较热/干燥的种群中具有更高的耐旱性。此外，共同园中繁殖体的可塑性较低，特别是来自最热/最干燥种群的繁殖体。我们没有发现生长-耐旱性权衡，并且在自然种群中很少有性状与死亡率有显著关系，这表明所测量的性状之间的种内性状变异并没有强烈介导对干旱胁迫的响应。我们的研究结果强调了干旱胁迫下性状介导响应的局限性以及复杂的 G×E 相互作用，这些相互作用可能是干旱环境下森林耐旱性变异的基础。
