DEVELOPMENTAL STABILITY OF FLOWERS, EMBRYO ABORTION, AND DEVELOPMENTAL SELECTION IN PLANTS

Fluctuating asymmetries in morphology originate from developmental err ors during ontogeny, and a general failure of the same developmental p rogramme may in outcrossing plants give rise to high levels of embryo abortion caused by developmental failure in early stages of cell diffe rentiation. I tested whether developmental errors expressed in flower asymmetry are associated with early embryo abortion caused by developm ental failure in hand-pollination experiments on rosebay willowherb (E pilobium angustifolium) (Onagraceae). Floral symmetry reliably reflect s pollinator rewards of individual plants. Pollinators prefer symmetri cal flowers over asymmetrical ones, visit flowers assortatively with r espect to symmetry, and avoid flowers with experimentally increased as ymmetry. Embryo abortion rates are strongly positively related to flor al asymmetry of both pollen donor and recipient, implying that both ma ternal and paternal plants affect embryo failure. Floral fluctuating a symmetry thus may be related to an important component of developmenta l selection in outcrossing plants such as rosebay willowherb.