Collaborative Research: Effects of Herbivory and Stress on Seaweed Resource Acquisition, Allocation Patterns, and Fitness

合作研究：食草和应激对海藻资源获取、分配模式和适应度的影响

• 批准号: 9901138
• 负责人: Megan Dethier
• 金额: $ 24.08万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-04-01 至 2002-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9901138&HistoricalAwards=false
• 关键词: Collaborative; Research; Effects; Herbivory; Stress

Dethier This research will investigate how an ecologically important intertidal fucoid alga (Fucus gardneri) allocates resources in response to variation in two key environmental variables, herbivory and desiccation stress (such as that experienced high in the intertidal zone). These variables are typically studied independently, yet it is their combined effect on seaweeds that must be important in nature. Algae must make "decisions" about how to allocate acquired energy to growth, reproduction, deterrency (e.g., anti-herbivore chemicals), and other key life-history functions, particularly when stress reduces resource acquisition capacity. While resource allocation patterns are being investigated intensively in terrestrial plants, almost no comparable work exists for algae, despite their ease of manipulation, abundance, interesting phylogenetic contrast to vascular plants, and important roles in nearshore marine ecosystems. In addition, virtually nothing is known about the consequences of allocation patterns to seaweed fitness. Fitness here is represented as the finite rate of population growth. Linking physiology to fitness is critical because changes in growth, or even reproduction, may not translate to effects on seaweed populations. In this project, a simple model that balances resource acquisition will be developed first (as Net Primary Production) against all known major resource allocation sinks for fucoids (growth, reproduction, phlorotannins, storage, exudation, loss to herbivores). This model will provide a tool to compare the physiological response of Fucus to gradients in stress and herbivory in the field and when manipulated in mesocosms. The research will involve: 1) observations of field populations of fucoids to quantify variation in their allocation patterns across natural gradients in herbivory and stress; 2) physiological measurements in the laboratory of Net Primary Production (emersed and immersed) and the other terms of the model for field-grown thalli; 3) manipulation both in the field and in laboratory mesocosms of the key variables of stress (emersion time, desiccation) and herbivory where thalli will be raised to reproductive size under these conditions, and then their allocation patterns will be assessed; and 4) development of demographic models to estimate population growth rates from life-history transitions measured in thalli across an intertidal gradient in stress and herbivory. Preliminary studies of the chemical composition and deterrency of extracts thought to contain anti-herbivore compounds will also be performed.The approach is designed to evaluate several specific issues involving resource allocation in, and its consequences for, intertidal seaweed populations that have broader implications than the response of seaweeds to stress and herbivory. Although virtually all previous studies of resource allocation in organisms assume that resource acquisition is constant, this project will test this assumption with measurements of Net Primary Production. Net Primary Production hypothetically varies across intertidal gradients in stressful conditions. If the assumption is false, allocation trade-off comparisons would not be valid without accounting for variation in resource acquisition. It is also hypothesized that there is a critical stress level above which reallocation among resource sinks is not possible. A physiological limit to the capacity to reallocate resources has rarely been addressed. Finally, allocation patterns demonstrated in adult organisms often are assumed to represent an important aspect of fitness or adaptedness. Yet, the adult phase might not be the most important life history stage in contributing to the population growth rate, and thus persistence of the populations. Sensitivity/elasticity analyses of the demographic models will determine which life history transitions (e.g., adult survival and reproduction versus recruitment) are most critical to the population growth rate, and thus, if allocation patterns within adults are important to seaweed population growth. . - This research will provide the first integrated approach to questions of resource allocation in seaweeds, and will demonstrate to what extent environmental harshness (biotic or abiotic) is reflected in algal performance. In this way, it will provide a link between physical changes (such as might occur during global warming) and the ability of algal individuals to grow and reproduce and seaweed populations to persist.

Dethier这项研究将调查如何生态上重要的潮间带岩藻（墨角藻gardneri）分配资源的变化，在两个关键的环境变量，食草动物和干燥应力（如经历了高的潮间带）。这些变量通常是独立研究的，但它们对海藻的综合影响在自然界中一定很重要。藻类必须就如何将获得的能量分配给生长、繁殖、繁殖（例如，抗草食动物化学品），以及其他关键的生活史功能，特别是当压力降低资源获取能力时。虽然陆地植物的资源分配模式正在深入研究，几乎没有可比的工作存在藻类，尽管它们易于操作，丰富，有趣的系统发育对比维管植物，在近岸海洋生态系统中的重要作用。此外，几乎没有什么是已知的分配模式海藻健身的后果。这里的适合度表示为有限的人口增长率。将生理学与健康联系起来是至关重要的，因为生长甚至繁殖的变化可能不会转化为对海藻种群的影响。在这个项目中，将首先开发一个简单的模型，平衡资源获取（作为净初级生产力）对所有已知的主要资源分配汇岩藻（生长，繁殖，根皮单宁，存储，渗出，损失草食动物）。这个模型将提供一个工具，比较墨角藻的生理反应梯度应力和草食动物在外地和操作时，在围隔。研究将涉及：1）观察岩藻的田间种群，以量化其在食草动物和压力下的自然梯度分配模式的变化; 2）在实验室中进行的净初级生产力的生理测量（浮现和浸没）和田间生长的菌体模型的其他术语; 3）在野外和实验室围隔生态系统中操纵压力的关键变量（羽化时间、干燥）和草食性，在这些条件下将菌体培养到生殖大小，然后评估它们的分配模式;和4）人口模型的发展，估计人口增长率从生活史的过渡测量在菌体跨越潮间带梯度的压力和草食动物。初步研究的化学成分和determination的提取物认为含有抗草食动物compounds也将performed.The方法的目的是评估几个具体的问题，涉及资源分配，其后果，潮间带海藻种群，有更广泛的影响比响应海藻的压力和草食动物。虽然几乎所有以前的生物资源分配研究都假设资源获取是恒定的，但本项目将通过测量净初级生产力来验证这一假设。净初级生产力假设在压力条件下跨潮间带梯度变化。如果假设是假的，分配权衡比较将是无效的，而不考虑资源获取的变化。还有人假设，存在一个临界压力水平，超过这个水平，资源汇之间的重新分配就不可能。重新分配资源的能力的生理限制很少得到解决。最后，在成年生物体中表现出的分配模式通常被认为是适应性或适应性的一个重要方面。然而，成年阶段可能不是最重要的生活史阶段，有助于人口增长率，从而持久的人口。人口统计模型的敏感性/弹性分析将确定哪些生活史转变（例如，成体生存和繁殖与补充）对种群增长率最为关键，因此，成体内的分配模式对海藻种群增长是否重要。. - 这项研究将提供第一个综合的方法来解决海藻资源分配的问题，并将展示在何种程度上环境的严酷性（生物或非生物）反映在藻类的性能。通过这种方式，它将提供物理变化（例如全球变暖期间可能发生的变化）与藻类个体生长和繁殖以及海藻种群持续存在的能力之间的联系。