Predators alter ecosystems both by reducing the abundance of prey and by inducing change in species traits that influence ecosystem function. These trait-mediated predator effects on ecosystems depend on the evolution of both prey traits and the responsiveness of those traits to predation risk. The evolutionary history of predator and prey thus underlies the influence of predators on communities and ecosystems. The PIs will introduce predator cues to experimental streams containing Trinidadian guppies (Poecilia reticulata) from populations that have been isolated from predators for zero to thousands of years. Measurements of guppy behavior, metabolism, and nutrient processing will assess the influence of predators on guppy traits and the dependence of predator effects on the evolutionary history of predator and prey. Corresponding measures of invertebrate and algal communities, primary productivity, and nutrient cycling will assess how induced trait change translates into ecologically meaningful differences in stream communities and ecosystem processes.
Human-driven top-predator loss is a global threat to biodiversity and ecosystem services. Understanding the mechanisms by which predators structure natural systems is necessary to predict biodiversity and ecosystem services into an uncertain future. Recent evidence indicates that evolution in contemporary time can greatly affect the outcome of ecological processes, and the PIs will assess how rapid evolution by prey mediates the influence of predators on natural systems. One PhD student will be trained in conducting this research, and the PIs will link this research to ongoing outreach with high school biology students, using hands-on research projects to teach principles of biology.
