Evans 9318433 Many organisms, when faced with unfavorable environmental conditions, respond by slowing or arresting growth and development. At one end of the scale, animals such as bears have the ability to slow metabolism by hibernating. At the other end of the spectrum, many higher plants have the ability to more or less arrest growth and development of seeds until favorable conditions are experienced. This dormancy of seeds has led to the existence of seed banks--populations of dormant, viable seeds in the soil. Despite the profound implications for the ecology and evolution of plants, virtually no information is available on how dormancy affects other traits. Two experiments will address this question in the short-lived perennial desert mustard Lesquerella fendleri. The first explores whether past evolution has led to adaptive syndromes of germination requirements and post- germination traits. The second asks how evolution could act by performing an artificial selection experiment. This work has applied value in several regards. Efforts to understand plant responses to environmental change will remain incomplete (and perhaps erroneous) until we understand the important, but neglected, seed stage of the life cycle. Knowledge of the seed stage is also critical for plans to revegetate human- impacted lands.
