In this project, the researchers will investigate mechanisms that promote the coexistence of insect species that share plant species as their food source. Identifying and understanding the factors that allow for the coexistence of species is central to ecological theory. This research will focus on insect species that rely on milkweeds, a diverse and charismatic group of plants. The investigator will test the long-standing hypothesis that each insect species thrives under different (but not all) conditions and that such "trade-offs" prevent any one species from excluding all others. This hypothesis will be experimentally tested in natural populations in New York State. Milkweed plants exhibit high levels of genetic variation for six defensive and nutritional traits (chemical toxins, latex, nitrogen levels, etc). These traits can negatively affect herbivore species and are often strongly modified (or "induced") following initial attack by insects. Thus, the resource base for insect communities is highly dynamic. The investigators will test whether trade-offs in the performance of insects on different plant phenotypes (generated by genetic variation or induced defenses) allow variation in plant populations to maintain insect diversity. This research will also test the prediction that insect species that are less vulnerable to plant defenses will have a high susceptibility to predation or have a low ability to colonize new plant patches. Using novel field manipulations, these factors will also be tested as mechanisms promoting diversity.
The insect-milkweed system is highly suitable for the development of laboratory and teaching tools for K-12 education, and the investigator will be involved in a variety of activities designed to bring science to K-12 classrooms and to develop teacher training tools.
