PATTERNS OF MULTIPLE PATERNITY IN POPULATIONS OF RAPHANUS SATIVUS

Although multiple paternity has been documented for a large number of species, detailed studies of variation in multiple paternity among broods, individuals, and populations are lacking. We measured the extent of multiple paternity in the multi-seeded fruits of wild radish, Raphanus sativus, from three natural populations in southern California. Every parent sampled produced one or more multiply sired fruits, and, in most plants, over half the fruits analyzed proved to be multiply sired. In all, 75% of the 388 multi-seeded fruits analyzed showed multiple paternity. Among these fruits, the minimum number of paternal donors ranged from one to four, with a mode of two paternal parents. The fraction of multiply sired fruits varied from 68-85% among populations and from 40-100% among plants. Plants were heterogeneous for multiple paternity in the 1984 population. A significant positive correlation between multiple paternity and number of fruits per plant suggests that plants preferentially abort single sired fruits. The total number of mates that could be detected for entire plants ranged from 3-14 with a mode of seven. Multiple paternity is likely to be important in other species producing multi-seeded fruits.