CAREER: ECO-EVOLUTIONARY DYNAMICS: WHAT ARE THE CAUSAL LINKS BETWEEN POPULATION DENSITY, NATURAL SELECTION AND PHENOTYPIC CHANGE?

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Fostering the development of early-career teacher-scholars strengthens the nation's research capacity while contributing to an educated workforce capable of making complex decisions. This CAREER project integrates interdisciplinary research and creative educational opportunities to gain novel insights into the causal links between evolutionary change and population ecology. Natural selection, phenotypic change, and population size are often related, but we know little about the causes that underlie these relationships. The research takes advantage of rapid evolutionary change observed in the invasive western bluebird to investigate these causal relationships, and engages high school, undergraduate, and graduate students to think critically in order to solve problems and answer questions. Western bluebirds depend on successional habitat and must continually colonize new areas to survive. In previous work, the investigator discovered rapid shifts in aggression, population density, and natural selection that accompanied recolonization cycles. Newly colonized populations have low density, high aggression, and positive selection on aggression; older populations have high density, low aggression, and strong negative selection on aggression. These recurring cycles provide a unique opportunity to investigate the causal links between population density, natural selection and phenotypic change. The investigator will combine several approaches to determine these links: experimental manipulation of population density; observations of how changing density correlates with aggression; experimental manipulation of food availability and survival to identify changes in aggression and population size; and estimation of quantitative genetic parameters related to aggressiveness. Results will be integrated to resolve the causal links between evolutionary (selection for aggression) and ecological (population density) changes in these populations. This system is exceptionally amenable to manipulation of ecological interactions through the provision of nesting boxes, and the need for western bluebirds to recolonize new areas requires rapid evolutionary change. The ability to study populations at different stages of a colonization cycle provides diverse contexts to examine the links between components of an eco-evolutionary feedback loop. A particularly novel broader impact of this research is the engagement of cognitively delayed students to help them gain important life skills. Outreach to and collaboration with citizen scientists, the Confederated Salish and Kootenai Tribes, conservation groups, wildlife officials, and landowners will significantly broaden educational opportunities and the dissemination of research results.