Mutualistic endophytes have become asymptomatic and seed-transmitted, analogous to plant organelles. They are widespread in certain grass genera and tribes, suggesting that the symbiosis preceeded speciation of the hosts. There are two major research projects in the lab at present, in addition to a number of graduate student research projects. One major line of research concerns the consequences of the rapid spread of endophyte-infected grasses in natural and managed communities. Symbiotic microbes are potential regulators of diversity and productivity in ecological communities yet they have been rarely considered in empirical studies or theoretical models of community structure.
Infected plants are toxic to herbivores and are more competitive than uninfected grasses.
Long-term field experiments have been established to investigate how endophyte infection affects the ability of tall fescue to invade plant communities and to displace resident species, resulting in a loss of biodiversity. The relative importance of herbivore resistance vs environmental stress tolerance are being explored in a series of ancillary field experiments. In the near future, we plan to investigate the role of the endophyte infection in tall fescue as a mechanism driving small mammal population cycles as observed in the locally abundant prairie vole, Microtus ochrogaster. A second research area focuses on the interaction between the parasitic fungus Atkinsonella hypoxylon with its host grasses in the genus Danthonia in a small region of intense coevolutionary interactions. The ecological and genetic factors associated with a host range shift of the fungus onto new species that has occurred only in a small area of the southern Appalachians are being investigated.