Plants, being at the base of almost all food chains, are responsible for feeding the world. In other words, plants provide the necessary energy to sustain all animal life either directly (through herbivory) or indirectly (because carnivores eat herbivores). Because of this tremendous pressure on plants, they have evolved a remarkable diversity of strategies to defend against being consumed. For example, plants possess a variety of heritable physical (e.g., thorns, spines) and chemical (e.g., toxins such as cyanide) traits that ward off herbivores. Theory, observations, and experiments have all implicated insect herbivores as key agents shaping the evolution of plant traits. How plant populations respond to this selection in real time over multiple generations, however, is virtually unknown. This project will address this major gap in current scientific understanding with newly developed molecular techniques to fingerprint genetic individuals of the common evening primrose (Oenothera biennis). Because this project will be conducted in field plots containing plants of known genetic identity either subjected to or protected from insect herbivory, the investigators will gain new insight into both the evolutionary process in general and the specific traits that evolve in response to insect herbivore attack under natural environmental conditions. This project will be one of the most rigorous investigations of the evolution of plant defense performed to date, and will assess the impact of herbivores on changes in plant chemical defenses and genetic composition of the population. In addition, responses of the insect community to changes in the genetic make-up of the plant populations will be determined.
Broader impacts of this study include educational efforts directed to K-12 students, undergraduates, graduate students, and the general public. Because the work proposed examines evolutionary changes over relatively short time scales, engaging teachers and the general public can be readily accomplished through outreach efforts and field trips. The message of evolution by natural selection and plant-herbivore interactions will be taken into K-12 classrooms via an established program at Cornell University (Cornell Institute for Biology Teachers).
