APPARENT VS EFFECTIVE MATING IN AN EXPERIMENTAL POPULATION OF RAPHANUS-SATIVUS

Effective mating in plant populations need not occur during periods of peak pollinator activity and flowering. We measured seasonal and diur nal patterns of pollinator activity, pollen and ovule availability, an d seed production in an experimental population of Raphanus sativus to infer the times of reproductively effective mating. On a seasonal sca le, we found that most ''effective matings'', those resulting in matur e seeds, occurred very early in the season, well before the peak of fl owering and pollinator activity. At a finer scale, diurnal schedules o f flower opening, stigma saturation with pollen, and pollen removal in dicated that most effective matings occurred before noon, even though pollinator activity increased later in the day. These patterns may be most common in populations that are not pollen limited, but other ecol ogical factors (e.g. seed predation, resource depletion) could weaken the correspondence between pollination and effective mating.