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

皇家岛国家公园是一个有狼和驼鹿居住的岛屿，在过去的60年里一直在进行研究。最近，狼的数量急剧下降，濒临灭绝，国家公园管理局的回应是将大陆狼重新安置到该岛。这项研究的一个目标是检验生态学中一个长期存在的观点，即种群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驱动的，如食物的可获得性或捕食造成的死亡。知道哪种影响更强--随机事件或可预测的模式--对生态和保护具有重要影响。这项研究的第二个目标是基于这样一个观点，即食草动物和食草动物之间的关系间接地受到食草动物与它们所吃植物的关系的影响。植物自然会产生食草动物不喜欢的化学物质(数量不一)，并帮助最适合生长的植物免受过度侵袭。这项研究旨在了解这些食草动物和植物之间的关系是如何影响食物链的，从而影响食肉动物。研究团队将参与教育推广、公共参与和创新的艺术-科学合作，重点关注广泛的公共利益物种。研究的第一个目标是检验历史偶然性假说：种群动态在很大程度上是一系列随机事件的结果，其特征是(I)遗产效应在长度上与这些事件之间的等待时间相当，(Ii)个别随机事件的不同性质。这一目标将通过使用最新开发的统计方法分析实地数据来实现。对这一假说的支持可以解释为什么生态惊讶是常见的，为什么生态学家更擅长解释过去而不是预测未来，以及为什么种群往往在更长的时间内表现出弱的密度依赖。第二个目标是检验这样一个假设，即食草动物的捕食和化学生态对食物链有相对强烈的影响。最近的理论表明这一假设是可信的，对此进行实证检验需要一个像皇家岛这样的系统，在那里捕食的影响是有据可查的。这项测试涉及通过量化植物次生化合物如何影响驼鹿在觅食斑块内和之间的觅食来参数化“毒素依赖的功能反应”。这一裁决反映了NSF的法定使命，并通过使用基金会的智力优势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.