The effect of floral display and pollinator behavior on pollen-mediated gene dispersal in Mimulus ringens

Most flowering plants require animal pollinators to transfer male gametes between pollen donors and pollen recipients. As pollinators visit flowers, their movement patterns and the dynamics of pollen placement, transport, and removal influence the diversity and quality of mating opportunities. In bee pollinated plants, the amount of pollen carried between a pollen donor flower and the next several potential recipients, a process known as pollen carryover, depends on how the pollinator interacts with the pollen load it carries. In addition, because most plants display several flowers at once, mating may be further complicated by interactions between flowers grouped into a floral display. To better understand the dynamics of pollen dispersal in plants with single- and multi-flower displays I quantified pollinator movements, pollinator grooming behavior, pollen dispersal, and pollen-mediated gene dispersal in linear arrays of Mimulus ringens, a bumble bee pollinated wetland plant.; Pollen mediated gene dispersal in Mimulus ringens is strongly leptokurtic. Most of the pollen and genes dispersed from a donor flower are distributed over the first four recipient flowers in the floral visitation sequence. Pollen is frequently dispersed to flowers on the same plant, resulting in substantial levels of self-fertilization. However, small amounts of pollen from a donor flower are dispersed to flowers probed much later in the visitation sequence; up to 23 flowers beyond the pollen donor. The pollen dispersal curve's extended tail has the potential to reduce the extent of spatial genetic structure within and among populations.; The pollen dispersal distribution has a longer tail in multi-flower displays than in single-flower displays. This suggests that as a pollinator visits successive flowers in a plant's floral display, pollen removed from the first flower visited may become buried under pollen removed from flowers visited successively on the display. When pollinators groom intensively during transitions between floral displays, buried pollen grains may be re-exposed, making them available for deposition onto recipient stigmas. This is the first study to demonstrate that an interaction between floral display size and patterns of pollinator grooming significantly affects patterns of pollen-mediated gene dispersal.