DISSERTATION RESEARCH: Plant defenses in African savannas: testing the effects of induced and associational defenses on plant phenotype, fitness and diversity

论文研究：非洲稀树草原的植物防御：测试诱导防御和关联防御对植物表型、适应性和多样性的影响

• 批准号: 1601538
• 负责人: Robert Pringle
• 金额: $ 1.64万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2018-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1601538&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; Plant; defenses; African

Understanding the ways in which plants modulate their vulnerability to herbivores is central to understanding patterns of biodiversity and ecosystem functioning. Many plants have physical defenses such as spines, thorns, or prickles that protect them against large mammalian herbivores (e.g., elephants, giraffes, deer, and elk); however, producing and maintaining these defenses is energetically costly. As a result, plants that produce more spines and thorns are less vulnerable to herbivory, but also have fewer resources to invest in growth and reproduction, two critical components of plant fitness. This tradeoff is particularly acute for plants in dry or infertile African savannas, where resources (e.g., water and nutrients) are scarce and the risk of being eaten by large herbivores is high. As a result, theory predicts the emergence of strategies that maximize the effectiveness of defenses while reducing their cost. Two such strategies are induced defenses (produced rapidly in response to damage by herbivores) and associational defenses (reduced incidence of herbivory derived from growing in close proximity to a well-defended neighbor). The goal of this project is to evaluate the relative effectiveness of, and interactions between, these anti-herbivore strategies and to determine how positive associational interactions among plants of different species alter patterns of resource investment. Plants facing the same evolutionary pressures frequently converge on similar suites of defensive characteristics, known as defense syndromes. In African savannas, individuals of the same species can exhibit strongly contrasting defense syndromes depending on their proximity to well-defended neighbors. Plants growing beneath thorny tree canopies, for example, produce fewer spines and exhibit a diminished induced response to simulated herbivory relative to conspecifics growing in open habitat. The researchers hypothesize that this difference is maintained by a disparity in the environmental cues that govern defensive investment in plants and will test this hypothesis using transplant experiments of focal plant species conducted inside and outside of large-herbivore exclosures in the Mpala Research Centre, Kenya. The researchers will also perform surveys of multiple species to evaluate how common intraspecific variation in defense syndrome is across plant taxa. By investigating the biotic and/or abiotic forces that maintain discrete intraspecific defense syndromes, this research will elucidate the independent and interactive effects of different anti-herbivore strategies on plant fitness and help inform the management of rangelands and the conservation of native vegetation in African savannas.

了解植物调节其对食草动物的脆弱性的方式对于理解生物多样性和生态系统功能的模式至关重要。许多植物都有身体防御能力，例如刺，刺或刺，可保护它们免受大型哺乳动物的食草动物（例如大象，长颈鹿，鹿和麋鹿）的侵害；但是，产生和维护这些防御量在大力上是昂贵的。结果，产生更多刺和荆棘的植物不太容易患草食，但资源较少用于增长和繁殖，这是植物健身的两个关键组成部分。对于干燥或不育的非洲稀树草原中的植物，这种权衡特别严重，资源（例如水和营养物质）很少，被大量食草动物食用的风险很高。结果，理论预测了策略的出现，这些策略在降低成本的同时最大程度地提高了防御能力的有效性。两种这样的策略是诱发的防御措施（响应食草动物的损害而迅速产生）和联想防御（降低了与邻近邻近的邻近生长有关的草食性发生率）。该项目的目的是评估这些抗动物策略的相对有效性和相互作用，并确定不同物种植物之间的积极关联相互作用如何改变资源投资的模式。面对相同进化压力的植物经常在类似的防御特性套件上汇聚，称为防御综合症。在非洲的稀树草原中，同一物种的个体可以表现出强烈的防御综合征，具体取决于其与预防良好的邻居的接近。例如，在棘手的树冠下生长的植物会产生较少的棘突，并表现出诱导的对模拟草食生物相对于在开放式栖息地生长的食草的反应。研究人员假设这种差异是由于控制植物防御性投资的环境线索的差异而维持的，并将使用肯尼亚MPALA研究中心的大草饲料内部和外部进行的焦点植物物种的移植实验来检验这一假设。研究人员还将对多种物种进行调查，以评估植物类群中国防综合征的普遍内部变异。通过调查维持离散的种内防御综合征的生物和/或非生物力量，这项研究将阐明不同抗Herbivore策略对植物健身的独立和互动效果。