PYI: Plasticity, Gene Flow, and Differentials in Plant Reproductive Fitness

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This five-year Presidential Young Investigator Award will permit Dr. Diane L. Marshall of the University of New Mexico to maintain a highly productive activity level in her scientific research. Within an evolutionary ecology framework, she is continuing studies of plant population biology. Her principal work examines patterns of variation in plant reproduction and fitness (the term "fitness" refers to reproductive success and the relative differential effects brought about by natural selection). For the past several years, the wild radish, Raphanus sativus, has been the subject species of interest for exploring questions pertaining to plant mating systems (i.e., pollination, sexual selection, and paternity). Results demonstrate effects due to genetic identity of pollen donors, as well as variable responses on the part of individual pollen recipients. This work has been an important contribution in quantifying gene flow in plants. Future endeavors with another species will combine field work at the Sevilleta Long- Term Ecological Research site with greenhouse results. Apart from this work is that which has been done on a legume, Sesbiana. Recent investigations reveal that this species shows plasticity in response to stresses such as water or nutrient limitations, and that seed size is only one of several components of yield response. Future research will document the nature of plastic responses across a range of habitat types and plant species. Beyond allowing expansion of pilot studies of variation in plant secondary chemistry and its linkages to plant demography and herbivore pressure, this award will also guarantee that Dr. Marshall is able to supplement her mastery of electrophoretic techniques by developing expertise in the newer, more powerful ones such as "DNA fingerprinting," using restriction fragment length polymorphisms.