We are interested in understanding the ecological and genetic mechanisms that encompass the key life history transition between perenniality and annuality. Life history traits controlling the timing of individuals’ growth, reproduction, and death represent some of the most spectacular adaptive differences among plants and animals. One of the main differences between annuals and perennials is when and how they switch from vegetative growth to flowering, a decision that has direct implications for reproduction and fitness. New research on the genetics of flowering allows us to ask mechanistic questions about the adaptive significance of the cues used by plants to transition between vegetative and floral phases and shed light on the genetic changes that might occur during evolutionary transitions between annual and perennial life strategies.
The Western North American wildflower, Mimulus guttatus, is an ideal system to investigate life history transitions. The species encompasses both facultative annual and perennial populations that are geographically widespread. Perennial populations are widespread in areas with permanent streams with year-round moisture. Annual populations are typically located in habitats that have abundant soil moisture in the spring and early summer, but little during the late summer. Previous common garden experiments consistently show that plants from annual populations tend to flower earlier and have smaller floral and vegetative sizes than plants from perennial populations, allowing them to flower rapidly before the onset of summer drought. Perennial plants are larger and more competitive in their native sites, and they cycle repeatedly through vegetative and reproductive modes.
Our research examines three main questions:
1. What are the cues plants use to time major life history decisions?
2. How has selection affected allocation strategies to flowering versus growth?
3. What are the evolutionary relationships among ecotypes and what is the genetic architecture of trait differences?