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

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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.