Organisms in nature live in populations that may remain stable, grow, fluctuate in size, or go extinct. The physical environment, the presence of natural enemies, the genetic properties of a population and the abilities of individuals to adapt to the environment all influence population size and persistence. As ecosystems experience rapid climate change, it is imperative to understand how environmental and genetic variation affects the persistence of vulnerable populations. To focus on this critical problem, populations of a native willow beetle experiencing extreme climatic conditions in the Sierra Nevada Mountains of California will be investigated. Populations studied for over a decade will be characterized using markers of genetic variation and environmental adaptation. Changes in population size will be related to these markers, to local topography, and to climatic conditions assessed by continuously recording weather loggers. Historical samples from these populations, some of which are now extinct, will be included in this analysis, offering a rare opportunity to analyze changes in populations for which the past environment is characterized. Experiments quantifying reproduction, larval survival, and adult over-wintering survival will assess potential mechanisms contributing to population persistence for beetles of differing genetic and environmental backgrounds.
Findings will provide unique insights into the ability of organisms to cope with and adapt to a rapidly changing environment, and will enhance understanding of the effects of genetic and environmental variation on ecological interactions among species. This project continues a unique, long-term population and climate dataset, and will thus provide a substantive contribution to knowledge of the effects of global climate change on natural systems. Finally, this program will support and mentor a large number of undergraduates, including groups traditionally underrepresented in environmental biology, working in the laboratory and field as a collaborative, interdisciplinary team.
