Breeding structure of a Yucca filamentosa (Agavaceae) population

Yucca filamentosa and its species-specific pollinator, the yucca moth, Tege ticula yuccasella (Lepidoptera: Prodoxidae), form a relationship that is of ten cited as a classic example of a coevolved plant-pollinator mutualism. O bservations of the moth's behavior have led to predictions that moth disper sal is relatively limited and that, as a consequence, the self-compatible Y . filamentosa should experience relatively high rates of self-fertilization , In contrast, analyses of its mating system indicated that Y. filamentosa was predominantly outcrossed. To better understand effective breeding patte rns in Y. filamentosa populations, 10 polymorphic allozyme loci were invest igated to analyze the breeding structure of a natural Y. filamentosa popula tion. Analyses revealed that Y. filamentosa is predominantly outcrossed, ha s multiply sired fruits, and that each fruit was sired by a different set o f pollen donors. The effective number of pollen donors per fruit ranged fro m 1.56 to 3.13, indicating that some correlated mating exists within fruits . Paternity analyses revealed that pollen moved from 6 m to 293 m (mean = 1 18 m) within the study population and that a minimum of 10% of the progeny were sired by pollen originating outside of the population. These results a re discussed in the context of the yucca-yucca moth mutualism.