LTREB Renewal: Instability, contingency, and global change in a terrestrial food chain

皇家岛国家公园是一个居住着狼和驼鹿的岛屿，在过去的六十年里一直在研究。最近，狼的数量濒临灭绝，国家公园管理局通过将大陆狼重新安置到岛上来应对。这项研究的一个目标是验证生态学中一个长期存在的观点，即人口波动更多地是由随机事件（如极端气候事件和疾病爆发）驱动的，而不是由可预测的模式（如食物的可用性或因捕食而导致的死亡率）驱动的。了解哪一种影响更强——随机事件还是可预测模式——对生态和保护具有重要意义。本研究的第二个目标是基于食肉动物和食草动物之间的关系间接受到食草动物与它们所吃植物的关系的影响。植物自然产生的化学物质（数量不同）对食草动物来说是不美味的，并帮助最适合的植物避免被过度浏览。这项研究旨在了解这些草食动物与植物的关系是如何在食物链中影响食肉动物的。研究团队将参与教育推广、公众参与和创新的艺术与科学合作，重点关注公众广泛关注的物种。研究的第一个目标是检验历史偶然性假说：人口动态主要是一系列随机事件的结果，其特点是：(i)遗留效应与这些事件之间的等待时间长度相当；（ii）单个随机事件的不同性质。这一目标将通过用最近发展的统计方法分析实地数据来实现。对这一假设的支持可以解释为什么生态意外很常见，为什么生态学家更擅长解释过去而不是预测未来，以及为什么人口在较长时间内往往表现出较弱的密度依赖性。第二个目标是验证捕食和草食的化学生态对食物链有相当强的影响的假设。最近的理论表明，这一假设是合理的，而对此的实证测试需要像皇家岛这样的系统，在那里，捕食的影响是有充分记录的。该测试包括通过量化植物次生化合物如何影响驼鹿在觅食斑块内和觅食斑块之间的觅食，来参数化“毒素依赖的功能反应”。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Isle Royale National Park is an island inhabited by wolves and moose, studied continuously for the past six decades. Recently, the wolf population collapsed to near extinction and the National Park Service responded by relocating mainland wolves to the island. One goal of this research is to test a long-standing idea in ecology that population fluctuations are driven by random events (such as extreme climate events and outbreaks of disease) more so than by predictable patterns such as the availability of food or mortalities due to predation. Knowing which influence is stronger – random events or predictable patterns – has important consequences for ecology and conservation. A second goal of this research is premised on the idea that relationships between carnivores and herbivores are indirectly affected by herbivores’ relationship with the plants they eat. Plants naturally produce chemicals (in varying amounts) that are unpalatable to herbivores and help the most fit plants from being overbrowsed. This research aims to understand how those herbivore-plant relationships reach up the food chain to affect carnivores. The research team will be involved with educational outreach, public engagement, and innovative art-science collaborations, focused on species of broad public interest.The first goal of the research is to test the Historical Contingency Hypothesis: population dynamics are largely the result of a series of random events characterized by (i) legacy effects that are comparable in length to the waiting time between such events and (ii) the disparate nature of individual random events. This goal will be achieved through analysis of field data with recently developed statistical methods. Support for this hypothesis could explain why ecological surprises are common, why ecologists are better at explaining the past than forecasting the future, and why populations tend to exhibit weak density dependence over longer periods of time. The second goal is to test the hypothesis that predation and the chemical ecology of herbivory have comparably strong influences on food chains. Recent theory indicates the hypothesis is plausible, and an empirical test of this requires a system like Isle Royale, where the influence of predation is well-documented. The test involves parameterizing a “toxin-dependent functional response” by quantifying how plant secondary compounds influence foraging by moose within and between foraging patches.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.