FAW: The Evolutionary Significance Of Physiological and Morphological Plasticity in Plantago lanceolata

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A critical question in plant population biology is how phenotypic plasticity affects response to natural selection to heterogenous environments. A classic example of physiological plasticity is the production of sun or shade leaves under different light conditions. One particularly interesting question is whether there is a trade.off between fitness within an environment and capacity for plastic response across environments. In this research, the investigator proposes to examine physiological, morphological and life history traits in Plantain (>>>Plantago> >lanceolata>) to address four questions: . Is there genetic variation for norms of reaction within and between natural populations? . How does the strength and direction of natural selection on these traits vary with light environment? . What is the relationship between plasticity and fitness within and across environments? .Is there short.term evolutionary response to microgeographic heterogeneity in selective pressures? The investigator will clonally replicate plants that have experienced different selective pressures for many generations. These clones will be planted and subjected to different shade regimes. Periodically, a variety of morphological and physiological measurements will be taken to examine the plants' physiological reactions. These data will permit the examination of genetic variation within and between populations for plant traits and for response of these traits to environmental variation. Fecundity and survivorship will be measured to determine the strength and direction of natural selection on the traits of interest in each environment. To test the hypothesis that local variation in selective pressures can lead to microgeographic evolutionary response, experimental mowing regimes will be continued for five years. Each year, a random sample of the seeds produced in each plot will be grown under uniform conditions to determine whether character means shown to be under differential phenotypic selection in the different treatments change in the predicted directions in successive offspring generations. This study will integrate ecological genetics and physiological ecology, and will thereby provide valuable information about the genetic basis and evolutionary consequences of phenotypic plasticity in natural populations.