Impact of sex on aspen distribution and response to abiotic drought stress

性别对白杨分布和对非生物干旱胁迫反应的影响

• 批准号: RGPIN-2017-04164
• 负责人: Thomas, Barb
• 金额: $ 1.82万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=710490
• 关键词: Impact; sex; aspen; distribution; response

The profound impact of drought on the fitness, physiology and health of plant species has been studied across a wide range of conditions. However, the linkage between abiotic stress and sex, particularly in long-lived clonal tree species has yet to be explored. The long-term objectives of this program are to: 1) understand the role of sex in stress resistance and distribution of aspen (Populus tremuloides Michx.) clones on the landscape, and 2) assess potential trade-offs in ecophysiology, growth and wood quality traits as mechanisms to resist abiotic stress (ie: drought). By studying both a natural forest system where abiotic stress is occurring and through artificial greenhouse experiments using seedlings, I will investigate if drought stress differentially affects males and females at different ages and by measuring clone size in natural stands, determine if there is a trade-off in the cost of reproduction vs clonal expansion and growth under abiotic stress. Differential expansion of one sex vs the other, could lead to a separation of males and females on the landscape and ultimately cause a shift in the distribution of this species. With the recent discovery (2015) of a simple DNA-based marker for sex now available for aspen, we can begin to explore these questions in depth. The literature tells us that males will outperform females in species where males and females are on different plants, because of a higher cost of reproduction in the female. The evidence to date in aspen is not convincing. Several factors appear to affect clone size including recolonization rates, fire return interval and moisture availability during flowering and seed dispersal. For example, clones tend to be smaller in the north where more recent recolonization has occurred and moisture is less limiting to seedling regeneration. Since sex has previously been determined when trees were flowering, it is unknown what the current sex ratio is across the landscape. A recent decline in aspen health across much of North America, due primarily to drought at the southern boreal forest fringe however, appears to be having a profound impact on the species range and may be having a serious impact on the sex distribution and ultimate persistence of this species on the landscape. In this Discovery Grant, I will test the hypothesis that males are out-performing females under drought conditions due to a reduced need to expend energy in reproduction, skewing the distribution of males and females on the landscape. A competing hypothesis is that females are equally represented on the landscape with no added cost to reproduction and maternal investment due to the small cost of seed production in aspen (no endosperm). A second component of the program will test the hypothesis that clones with higher wood density, will exhibit greater water use efficiency, greater resistance to damage of the water transport system and ultimately be more drought stress resistant.

干旱对植物物种的适应性、生理和健康的深刻影响已经在广泛的条件下进行了研究。然而，非生物胁迫和性别之间的联系，特别是在长寿的克隆树种还有待探讨。本项目的长期目标是：1）了解性别在白杨（Populus tremuloides Michx.）克隆的景观，和2）评估潜在的权衡生态生理学，生长和木材质量性状的机制，以抵御非生物胁迫（即：干旱）。通过研究两个自然森林系统的非生物胁迫发生，并通过人工温室实验，使用幼苗，我将调查干旱胁迫是否差异影响男性和女性在不同的年龄，并通过测量在自然林的克隆大小，确定是否有一个权衡的成本与非生物胁迫下的克隆扩张和生长的繁殖。一种性别与另一种性别的差异扩张，可能会导致景观上的男性和女性分离，并最终导致该物种分布的转变。随着最近（2015年）发现一种简单的基于DNA的性别标记，现在可以用于白杨，我们可以开始深入探索这些问题。 文献告诉我们，在雄性和雌性在不同植物上的物种中，雄性会胜过雌性，因为雌性的繁殖成本更高。迄今为止在白杨发现的证据并不令人信服。有几个因素似乎影响克隆大小，包括克隆化率，火返回间隔和开花和种子传播过程中的水分供应。例如，在北方，无性系往往较小，那里最近发生了干旱化，水分对幼苗再生的限制较少。由于性别以前是在树木开花时确定的，因此目前还不知道整个景观的性别比例是多少。然而，最近北美大部分地区的白杨健康状况下降，主要是由于南部北方森林边缘的干旱，似乎对物种范围产生了深远的影响，并可能对该物种在景观中的性别分布和最终持久性产生严重影响。 在这个发现补助金，我将测试的假设，即男性表现优于女性在干旱条件下，由于减少需要在繁殖中消耗能量，倾斜的男性和女性的分布景观。一个竞争性的假设是，女性在景观上的代表性是平等的，没有额外的成本，生殖和母亲的投资，由于种子生产成本低，在白杨（无胚乳）。该计划的第二个组成部分将测试假设，即具有较高木材密度的无性系将表现出更高的水分利用效率，对水运输系统的破坏具有更大的抵抗力，并最终具有更强的抗旱能力。