Plants continuously adjust their body plan to suit the environmental conditions in which they are growing. A good example of this is in the regulation of shoot branching. Axillary meristems, which are established in each leaf formed from the primary shoot apical meristem, can remain dormant as a bud, or they activate to produce a branch. The decision whether or not to activate an axillary meristem involves assessment of a wide range of environmental, physiological and developmental factors. Much of this information is transmitted via a network of interacting hormonal signals that can integrate multiple inputs to generate a rich source of systemically transmitted information, which is locally interpreted to regulate axillary bud growth. Most of our understanding of this network is based on the analysis of single gene, loss of function mutants in key network components. To allow a more quantitative assessment of the genetic architecture of shoot branching plasticity in natural populations, and its evolution in response to selection, we are using variation in shoot branching response to N availability in different Arabidopsis populations. We are comparing plasticity in natural accessions, multi-parent advanced generation intercross lines, and artificially selected lines. The results to date suggest that variation in plasticity is associated with distinct life history strategies.