Effects of Rapid Consumer Evolution on Community Dynamics: Predictions and Tests in a (nearly) Natural Food Web

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Populations of organisms have a remarkable capacity to adapt to environmental change. Adaptive evolution increases the relative abundance of individuals with genes for particular traits (genotype) that allow them to survive and reproduce better than those with different traits. An organism?s genotype determines how it interacts with its environment, including with other species. The variety of genotypes present in a population, and how much the environment changes, dictate not only how fast evolution will occur, but also how that population increases or decreases in abundance as the environment changes. Mathematical theory and simple laboratory predator-prey experiments demonstrate that the ability of a population to evolve markedly affects whether, and how quickly, it changes in abundance. The cycles of predator and prey abundance look very different with and without evolution. This project tests whether these evolutionary predator-prey cycles are important in understanding changes in species abundance in more natural conditions where weather varies daily, seasons come and go, and they are imbedded in a community of many species. The research will use replicate experimental ponds to document changes over time of freshwater phytoplankton abundances driven by the increases and decreases in the abundance of Daphnia, an animal that feeds on phytoplankton. The experiment will manipulate the amount of genetic variation in the Daphnia populations in order to change their capacity to evolve, and to determine how that affects seasonal changes in phytoplankton abundance and water clarity. Genomic methods will be developed to track evolutionary changes in the Daphnia populations. This project has practical value in the management of freshwater lakes since the capacity for Daphnia to evolve may determine when and how Daphnia regulates water clarity, a major feature of environmental quality in lakes. This project will provide research training and career mentoring for a postdoctoral scholar, and for graduate and undergraduate students. In addition, high school students will participate in conducting the field experiments through summer research experiences.