Effects of within-tree flowering asynchrony on the dynamics of seed and wasp production in an Australian fig species

Within-tree flowering asynchrony in figs, which may allow pollinating wasps to avoid the risks of dispersal in inclement conditions, has been predicted as a trait to be favoured in highly seasonal environments. Comparisons of such asynchronous figs with better-known species that exhibit within-tree synchrony might also be expected to reveal differences in the outcome of the conflict between pollinator wasp and fig seed production, and the dynamics of non-pollinating wasps. This paper presents data on wasp and seed production in Ficus rubiginosa Desf. ex Vent., an asynchronous species that occurs in the highly seasonal environment of south-eastern Australia. In contrast to recent studies of figs showing within-tree flowering synchrony, syconium size was the main determinant of wasp and seed production in F. rubiginosa. Non-pollinating wasps were highly prevalent but occurred in low numbers and appeared to have relatively little impact on pollinator wasp or fig seed production. Data on flower positions revealed that non-pollinating wasps occurred almost exclusively in the outer layer of flowers, while pollinators were more abundant in the inner flower layer, which may represent an area of enemy-free space. The ratio of seeds to female pollinator wasps, an index of fig sex allocation, was more seed-biased than in several New World fig species that exhibit within-tree synchrony. This last result supports the idea that within-tree fruiting asynchrony permits a degree of self-pollination in F. rubiginosa.