RUI: ARE THE EFFECTS OF SIZE-STRUCTURE ON TROPHIC CASCADES MEDIATED BY DEMOGRAPHIC FEEDBACKS?

在这个项目中，研究人员将研究捕食者的大小结构(即身体大小分布的差异)如何改变捕食者对猎物集合和猎物资源的影响。他们将进一步探讨大小类之间的相互作用(例如，同类相食和竞争)如何影响大小结构的发展。火蜥蜴是研究中的捕食者。这个项目将通过独立研究项目的开发和执行，为本科生提供学习科学方法的绝佳机会。它将显著提高肯塔基州三所本科院校的研究能力，其中一所是为少数族裔服务的院校。学生将在设计和实施实验、分析和管理数据以及向不同的公众受众交流科学方面获得第一手经验。这些机构中的每一个都缺乏独立的资源和项目来让学生参与研究。这个项目服务于国家的利益，通过严格的实验设计提供培训学生解决复杂问题所需的资源。先前的研究表明，顶级捕食者的大小结构可以显著影响营养相互作用，并可能解释观察到的营养级联强度的变化，但很少有实证研究集中在这些问题上。这个项目将结合实验和实地研究来测试关于捕食者大小结构、密度和食人族相互作用的假设，由此产生的群落动态，以及被认为产生大小结构变化的人口反馈机制。大小不一的捕食者既可以通过食人而表现出消耗性效应，也可以对其后代的生存表现出非消耗性效应。它们还影响其他捕食者和竞争者的数量。当这些不同的影响综合在一起时，可能会改变整个食物网，最终改变未来捕食者种群的大小结构，从而改变未来的营养级联。本科生将分组工作，通过一系列的中观实验和实地研究来测试所提出的产生大小结构变化的不同机制。实验和实地观察将量化捕食者大小结构对营养级联的影响，并确定人口反馈如何影响捕食者大小结构的年度变化。研究结果将为顶级捕食者的丧失或恢复如何影响生态系统提供新的见解，并对保护和管理产生影响。学生将参与科学教育活动，以吸引本科生、非理科专业学生和K-12学生参与，并参与互动学习模块，以将该项目的影响扩展到全国和全球的学生和公民。该项目得到了NSF刺激竞争性研究实验计划的支持。

In this project, the investigators will address how size-structure (i.e., variance in the body size distribution) of predators alters effects of the predators on prey assemblages and prey resources. They will further explore how interactions among size classes (e.g., cannibalism and competition) influence the development of size structure. Salamanders are the predators in the study. This project will provide exceptional opportunities for undergraduate students to learn the scientific method through the development and execution of independent research projects. It will significantly build research capacity among three undergraduate institutions in Kentucky, one of which is a minority-serving institution. Students will gain first-hand experience in designing and implementing experiments, in analyzing and managing data, and in communicating science to diverse public audiences. Each of these institutions lacks independent resources and programs to engage students in research. This project serves the Nation's interests by providing resources needed to train students in complex problem solving through rigorous experimental design.Previous research suggests that size structure of top predators can significantly influence trophic interactions, and may explain observed variation in the strength of trophic cascades, yet few empirical studies have focused on these questions. This project will combine experiments and field studies to test hypotheses regarding the interaction of predator size structure, density, and cannibalism, the resulting community dynamics, and the demographic feedback mechanisms thought to generate variation in size structure. Predators that vary in size can exhibit both consumptive effects, through cannibalism, and non-consumptive effects on the survival of their offspring. They also influence the abundance of other predators and competitors. When taken together, these diverse effects could modify entire food webs, ultimately altering the size structure of future predator populations and thus future trophic cascades. Undergraduate students will work in teams to test the diverse mechanisms proposed to generate variation in size structure using a series of mesocosm experiments and field studies. Experiments and field observations will quantify the impact of predator size structure on trophic cascades and determine how demographic feedbacks affect annual variation in predator size structure. Results will provide new insight into how the loss or recovery of top predators can affect ecosystems, with implications for conservation and management. Students will participate in science education activities to engage undergraduate non-science majors and K-12 students and contribute to an interactive learning module to extend the impacts of this project to students and citizens throughout the nation and globe.This project is supported by NSF's Experimental Program to Stimulate Competitive Research.