How do ecological interactions modify the impact of environmental fluctuations on populations?

影响自然生态系统生命的环境条件不断变化。虽然一些波动随季节周期、月亮周期或每日(昼夜)周期而发生可预测的变化，但所有这些波动都有一个看似不可预测的成分，以复杂的方式影响生物种群。从全球环境变化的许多模型中得出的一个中心预测是，环境波动的幅度将增加。预测这种增长将如何影响自然生态系统，需要了解波动的环境条件如何通过改变出生和死亡率直接影响生物种群，并间接通过改变捕食者、竞争对手和资源的丰度来影响生物种群。数学模型无疑将是建立我们对环境波动间接影响的理解的关键要素，因为它们可以很容易地配置到各种不同的生态系统中。不幸的是，目前的数学模型准确再现环境波动的间接影响的能力在很大程度上是未知的。该项目的目标是：i)利用现有模型和数据的长处，开发一个通用的数学理论，以预测不同的生态相互作用(捕食/食草和竞争/互惠)如何改变环境波动影响种群动态的方式，以及ii)通过对淡水栖息的纤毛虫原生动物的一系列实验室实验来验证该理论。这些单细胞模式生物特别适合这种类型的研究；物种对环境波动反应迅速，表现出广泛的取食行为，允许在小规模实验中配置现实的生态系统。该项目将把研究与教育和公众宣传结合起来，包括对一名博士后研究员、一名研究生、众多本科生和当地高中生的培训，这些人将通过皮博迪自然历史博物馆的一项外联计划参与进来。此外，通过该项目获得的理解将通过开发教学单元和教学软件用于教育。最终，提高我们对环境波动如何影响生物种群的理解将有助于我们管理和保护越来越多的物种和生态系统，这些物种和生态系统受到人类活动的威胁。

The environmental conditions which impact life in natural ecosystems are constantly fluctuating. While some fluctuations change predictably with the seasonal cycle, the lunar cycle or the daily (day/night) cycle, all have a seemingly unpredictable component that impacts biological populations in complex ways. A central prediction arising from many models of global environmental change is an increase in the magnitude of environmental fluctuations. Predicting how such an increase will impact natural ecosystems requires an understanding of how fluctuating environmental conditions impact biological populations directly, by altering rates of births and deaths, and indirectly, by altering the abundance of predators, competitors and resources. Mathematical models will undoubtedly be a key element in establishing our understanding of the indirect impacts of environmental fluctuations because they are easily configurable to a variety of different ecosystems. Unfortunately, the ability of current mathematical models to accurately reproduce indirect impacts of environmental fluctuations is largely unknown. This goal of this project is i) to draw on the strengths of existing models and data to develop a general mathematical theory to predict how the different ecological interactions (predation/herbivory and competition/mutualism) modify the way in which environmental fluctuations effect population dynamics and ii) to validate the theory using a series of laboratory experiments on freshwater-inhabiting ciliated protozoa. These single-celled model organisms are particularly well-suited to this type of study; species respond quickly to environmental fluctuations and exhibit a wide range of feeding behaviors, allowing realistic ecosystems to be configured in small-scale experiments. The project will integrate research with education and public outreach by incorporating the training of a postdoctoral fellow, a graduate student, numerous undergraduate students, and local high-school students who will be engaged through an outreach program at the Peabody Museum of Natural History. In addition, the understanding gained through this project will be directed towards education through the development of teaching modules and courseware. Ultimately, improving our understanding of how environmental fluctuations impact biological populations will aid our ability to manage and conserve the growing number of species and ecosystems at risk from human activities.