DISSERTATION RESEARCH: The Ontogeny of Defense in Tropical Rainforest Trees: Leaf Secondary Metabolites across Canopy-Understory Gradients of Resources and Stressors

论文研究：热带雨林树木防御的个体发育：跨冠层-林下资源和压力源梯度的叶子次生代谢物

• 批准号: 1405637
• 负责人: Phyllis Coley
• 金额: $ 1.51万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-06-01 至 2016-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1405637&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; Ontogeny; Defense; Tropical

This goal of this study is to examine how air pollution in a tropical forest affects the way in which plants produce a special class of chemicals in their leaves. Because plants cannot run from the insects seeking to eat them ("herbivores"), they produce these chemicals as a means of defense. The spice rack at a supermarket offers but a taste of the staggering diversity of plant defense compounds; tens of thousands have been cataloged, with many more still undescribed. The variety of chemical defenses arises from the fact that herbivores and pathogens have evolved resistance to particular defenses. Thus in what has been called an evolutionary arms-race, plants are constantly under pressure to evolve new defenses, while consumers are constantly under pressure to get around them. Tropical forests contain the highest diversity of plants and herbivores on the planet, so it is no surprise that these forests also contain the highest diversity of plant chemical defenses. Not just an artifact of the number of species in tropical forests, the diversity of plant chemical defenses is thought to be a central factor in both producing and maintaining tropical forest biodiversity. Thus, any large-scale alteration of the chemical landscape of a tropical forest may have wide-ranging effects.Air pollution, particularly ozone pollution, may constitute just such a landscape alteration. The focus of this study is ozone, which is produced as a result of fossil fuel combustion or biomass burning. In areas of the tropics where these activities are concentrated, ozone levels have been recorded above thresholds for impacts on leaf defense chemistry observed in other ecosystems. In temperate ecosystems, ozone pollution has been found to affect both the concentrations of defenses within leaves and the ability of herbivorous insects to locate appropriate host plants. Ozone affects the production and stability of certain chemical compounds more than others, so ozone pollution in a chemically diverse tropical forest is likely to affect some plant and herbivore species more than others. Based in a forest adjacent to the heavy shipping traffic of the Panama Canal, this study will investigate how the defense chemistry of an array of tropical tree species is affected by ambient ozone levels. Specifically, it will test how oxidative stress, foliar secondary metabolites, and herbivory interact. It will do so by mapping ozone levels in a forest and conducting a 2x2 factorial ozone and light manipulation experiment to assess how these variables affect production of foliar secondary metabolites.

这项研究的目的是研究热带森林的空气污染如何影响植物在叶子中产生一类特殊化学物质的方式。因为植物无法躲避想要吃掉它们的昆虫（“食草动物”），它们产生这些化学物质作为一种防御手段。超市里的香料架提供的只是一种植物防御化合物的惊人多样性；数以万计的物种已经被分类，还有更多的物种尚未被描述。化学防御的多样性源于食草动物和病原体已经进化出对特定防御的抗性。因此，在所谓的进化军备竞赛中，植物不断地承受着进化出新的防御手段的压力，而消费者则不断地承受着绕过它们的压力。热带森林拥有地球上最丰富多样的植物和食草动物，因此这些森林也拥有最丰富多样的植物化学防御也就不足为奇了。植物化学防御的多样性不仅是热带森林物种数量的产物，而且被认为是产生和维持热带森林生物多样性的核心因素。因此，热带森林化学景观的任何大规模改变都可能产生广泛的影响。空气污染，特别是臭氧污染，可能构成这样一种景观改变。本研究的重点是臭氧，它是由于化石燃料燃烧或生物质燃烧而产生的。在这些活动集中的热带地区，记录的臭氧水平超过了在其他生态系统中观察到的对叶片防御化学影响的阈值。在温带生态系统中，臭氧污染已被发现既影响了叶片内防御物的浓度，也影响了食草昆虫寻找合适寄主植物的能力。臭氧对某些化合物的产生和稳定性的影响比其他化合物更大，因此，在化学成分多样化的热带森林中，臭氧污染可能对某些植物和食草动物物种的影响比其他物种更大。这项研究以巴拿马运河附近的一片森林为基础，将调查一系列热带树种的防御化学如何受到环境臭氧水平的影响。具体来说，它将测试氧化应激、叶面次生代谢物和草食如何相互作用。它将绘制森林中的臭氧水平图，并进行2x2因子臭氧和光操纵实验，以评估这些变量如何影响叶面次生代谢物的产生。