It has always been assumed that pollen characters are determined by the genotype of the plant (from the classic nature- versus-nurture argument, pollen traits are assumed to be totally determined by 'nature'). However, recent experiments have shown that the environment can have important effects on pollen characters. For instance, work with wild radish demonstrated that pollen from plants grown under nutrient-limiting conditions sired fewer seeds than pollen from control plants. This proposal is centered around measuring the genetic and environmental contributions to variation in pollen traits in Silene alba, white campion, a common weed in the eastern United States. The pollen traits are pollen number per flower, pollen size, percent of pollen that has aborted, and the ability of pollen to sire seeds. Most of the work will consist of documenting how much natural variation in these traits exists in fields around New Jersey and, through transplant experiments, how the same genotype performs in different environments. The result will a precise measurement of the genetic and environmental contributions to a variety of pollen traits, and perhaps to paternity itself.
