The environment in which organisms live is not static but changes as a consequence of human activities, as well as geological and evolutionary processes. One particularly dynamic environment is that of a biological host within which microbes live. In these environments, change can be rapidly induced by the presence of the microbes themselves when they trigger host resistance responses. How does this environmental change shape the ecology and evolution of microorganisms, and how do they survive in such fluctuating environments? The goal of this project is to dissect the ecological and evolutionary responses of bacteria that live in the leaves of a host plant, A. thaliana, to changes that are induced in host plant chemistry. In so doing, this project will attempt to (1) identify the community of bacterial species that reside in this important host plant, (2) explore the community level interactions of these species as a function of biochemical changes in the host, particularly making use of genetic mutants that differ in their capacity for defense responses, (3) examine genome-wide patterns of genetic variation in an attempt to infer the evolutionary history of these species and (4) experimentally test the evolutionary capacity of microbes to adapt to novel host environments. The project is thus integrative, encompassing ecology, evolution, genetics, genomics and biochemistry, in an effort to develop a mechanistic understanding of biological response to a changing environment.
Most, if not all, species are faced with changing environments, although the timescale of this change varies. Of particular practical concern is whether we can predict the capacity of species to adapt to novel environments, and whether we can anticipate the extent of community level compositional change. Discoveries about the role of plant defense on the resident microbial community in ecological and evolutionary time should yield general principles that will be applicable across a broad spectrum of microbial communities. This project aims to discern these general principles. The project will also serve important educational missions, including (1) a role for high school and undergraduate students in the research, (2) a component to train K-12 teachers in microbial ecology, (3) efforts to include both a technician and graduate students from an under-represented group, and (4) hands-on presentations on biodiversity to nursery and elementary school students, including display of student made installments at The Field Museum in Chicago.
