Male and female reproductive success in the dioecious fig, Ficus hirta Vahl. in Guangdong Province, China: Implications for the relative stability of dioecy and monoecy

We studied components of male and female reproductive success in the fig, Ficus hirta from Guangdong Province, China. Specifically, we analyzed the composition and sex ratio of both pollinating (Blastophaga javana) and the two species of non-pollinating wasps associated with functionally male figs, as well as seed production in the functionally female figs. In male figs, a mean of 799 flowers produced a mean of 234 wasps (mean proportion of flowers developed in each fruit is ~31%). Female pollinating wasps (the only vectors for fig pollen) comprised the majority of all wasps in male syconia (~62.8%), indicating a relatively high fitness for the pollinator and the fig. The median sex ratio of the pollinators was 0.16 (mean ~24% males) and roughly reflects estimates of average foundress number (1.7). There are two common nonpollinators in male syconia of F. hirta: one, Sycoscapter hirticola, also exhibited a strongly female biased sex ratio, while the other, Philotrypesis josephi, was male biased. In female figs, a mean of 858 flowers produced a mean of 433 viable seeds (mean of flowers developed in each fruit is ~50%). Thus, similarly to other studies of dioecious species in which detailed data on wasp and seed production have been reported, female inflorescences (figs) generally appear to initiate more flowers than male inflorescences, and produce more seeds than male inflorescences produce female pollinator wasps. Compared with published studies of seed and wasp production in monoecious figs, F. hirta appears more efficient on a per syconium basis at both seed and female pollinator wasp production than monoecious species characterized by large numbers of flowers, high average foundress numbers, and high non-pollinator wasp loads. These comparisons suggest conditions that favor selection for (and stability of) either the monoecious or dioecious breeding system in figs.