MEASUREMENTS OF NATURAL SELECTION ON FLORAL TRAITS IN WILD RADISH (RAPHANUS RAPHANISTRUM). II. SELECTION THROUGH LIFETIME MALE AND TOTAL FITNESS.

It has often been suggested that selection on floral traits in hermaphroditic plants should occur primarily through differences in male fitness. However, measurements of selection on floral traits through differences in lifetime male fitness have been lacking. We measured selection on a variety of wild radish floral traits using lifetime male fitness measures derived from genetic paternity analysis. These male fitness estimates were then combined with estimates of lifetime female fitness of the same plants to produce measurements of selection based on lifetime total fitness. Contrary to the prediction above, there was no strong evidence for selection on floral morphology through male fitness differences in any of the three years of the study, but there was strong selection for increased flower size through female fitness differences in one year. The main determinant of both male and female fitness in all years was flower number; this lead to moderately positive correlations between male and female fitness in all three years.