POLLEN APERTURE POLYMORPHISM AND GAMETOPHYTE PERFORMANCE IN VIOLA DIVERSIFOLIA.

Pollen aperture polymorphism is studied in Viola diversifolia, where all plants produce three- and four-apertured pollen grains. We tested whether there are genetic differences among plants for the proportions of the different pollen morphs, and whether the morphs differ in gametophytic performance. Results show that the more apertures a pollen grain has, the more quickly it germinates but that few-apertured pollen grains have faster growing pollen tubes and longer life expectancies. The proportions of the different pollen morphs, together with pollen tube growth rates, may be inherited traits based on differences among maternal families. These results suggest that the different pollen morphs are favored in different pollination ecology situations. The production of several pollen morphs by the same individual could therefore be evolutionarily advantageous. © 1993 The Society for the Study of Evolution.