Click a leaf
The evolutionary ecology of mobility: Ecological genetics in Arabidopsis thaliana 
Arabidopsis thaliana occurs abundantly in fallow fields. Arabidopsis thaliana is well known for its use in molecular studies. However, being a recent addition to the flora of North America, and distributed over a wide geographic range, it also has an extremely interesting ecology. Because of the genetic tools developed for A. thaliana by a large scientific community, A. thaliana offers a unique system for investigating the genetic basis of species introductions, range expansion, and adaptation to broad geographies. While some argue that A. thaliana is not a real plant with a real ecology (!), our lab confronts the historical mobility of this weedy species head-on and asks questions about the ecology of mobile species. Mobility is a fundamental aspect of modern plant ecology. While not neatly fitting into the traditional paradigm of local populations reflecting past adaptation, a perspective that has been so richly studied since the earliest days of plant evolutionary ecology, mobile species offer different challenges to ecologists who are interested in how plants evolve in dynamic environments.
Our lab has been studying the seed dispersal, seed dormancy, and life history variation of A. thaliana. Seed dormancy behavior can strongly influence the geographic range of a species by influencing when or whether it germinates in a particular location. The timing of germination essentially sets the stage for the rest of the life of the plant. Variation in dormancy, therefore, may influence the ability of a species to expand its geographic range. A. thaliana shows variation in its dormancy behavior and overall life history. Most populations in North America are winter annuals. That is, they germinate in the autumn, overwinter as rosettes and flower during the late spring and summer. Populations in the northeastern US, in contrast, express seasonal variation in dormancy and flowering time: many seeds germinate int he spring, and several populations have been seen to flower in the autumn or winter as well as during the spring. Such variation has the potential to influence life-history expression at all stages of development and can influence basic demographic processes, including the number of generations completed within a single year.
Arabidopsis thaliana flowering and fruiting in the snow during December (Montague, MA). We are currently studying the adaptive significance and genetic basis of this life-history variation using quantitative genetic approaches, QTL analysis in the field and growth chambers, and controlled environmental manipulations with mutants and natural populations. Post doc Shane Heschel is leading the efforts to characterize the physiological basis of variation in germination behavior in natural populations. Our goals are to characterize the genetic constraints on plasticity of germination and to identify important genes associated with natural variation in these fundamental life history characters under diverse, ecologically realistic environments.
