Flower Specialization in a Passively Pollinated Monoecious Fig: a Question of Style and Stigma?

The stability of the mutualism between figs and their pollinator wasps depends on the patterns of seed and wasp production. In Ficus maxima, a passively pollinated monoecious fig, we estimated the correlations among different flower characteristics and determined their relationships with pollination success and pollinator oviposition. Across flowers, stigma length shows an allometric relationship with style length, and style length correlates negatively with style width. Longer-styled flowers are more likely to be pollinated and receive higher pollen loads. This is probably explained by their larger stigmatic surface that increases their chance of receiving the passively dispersed pollen. Consistent with findings in other species, flowers with longer styles are less likely to receive a pollinator’s egg. This oviposition pattern is probably explained by a combination of factors: (1) wasps ovipositor are too short to reach flowers with extremely long styles, and 17% of flowers are inaccessible; (2) sometimes, there are too few pollinators to use all accessible flowers; (3) oviposition is more difficult through the long stigmas and thin styles associated with long-styled flowers. Given the patterns of pollinator egg distribution, the style/stigma size relationship in F. maxima appears advantageous for the fig since it leads to preferential pollination of flowers that are not used by wasps. It might reflect flower functional specialization and contribute to the mutualism stability.