Coevolution of reproductive characteristics in three dioecious fig species and their pollinator wasps

Abstract

This study investigates dioecious fig species using a pollinator introduction experiment. Our aims were to determine: (1) whether there was a significant difference in foundress distribution between sexes per fig species; (2) whether fig size and foundress number affect reproductive success of dioecious figs; and (3) who is the 'controlling partner' in the fig/pollinator mutualism. Three dioecious fig species: Ficus semicordata, Ficus hispida and Ficus tinctoria from Xishuangbanna, China, were selected for this experiment. We found that there was no significant difference of the foundress number in female and male figs of F. semicordata, F. hispida and F. tinctoria. Also, the foundress number did not depend on the fig diameter. The numbers and the proportions of fig seeds and female wasp offspring significantly increased with more foundresses; and fig seed number was significantly higher than female wasp offspring in F. semicordata and F. hispida, but not in F. tinctoria. Our results indicate that figs are generally the 'controlling partner' in fig-wasp mutualisms in species with large figs, but not with small figs. Compared with published studies of reproductive success in monoecious figs, the dioecious figs seem to be more efficient in producing both seeds and wasp offspring when there is a high number of foundress.

Rapid evolution of pollinator-mediated plant reproductive isolation

“…The specialized nature of fig/pollinator interactions has made the system a focal point for studies of coevolution (Herre 1989;Ganeshaiah et al 1995;Weiblen 2004;Ma et al 2009). Each Ficus species is associated with one or several pollinating fig wasp species (Herre et al 2008) and approximately parallel patterns of phylogenetic diversity among more than 800 taxa has drawn much speculation on processes of diversification (Weiblen and Bush 2002;Machado et al 2005;Jackson et al 2008;Jousselin et al 2008).…”

The phenology of dioecious Ficus spp. tree species and its importance for forest restoration projects

“…In support of this assertion, Bronstein (1988) found that seed set in F. pertusa L. is pollinator-limited and Harrison et al (2000) suggested for dioecious figs that fig abortion of female trees is likely to reflect pollen limitation. Ma et al (2009) also showed that the numbers and the proportions of fig seeds and female wasp offspring significantly increased with numbers of foundresses.…”

Differential deployment of sanctioning mechanisms by male and female host trees in a gynodioecious fig–wasp mutualism

“…It is noteworthy that the natural foundress distributions of F. hispida show that receptive figs predominately contain either one or two foundresses (Patel and Hossaert‐McKey , Ma et al. ; Y. Q. Peng, unpublished data ). The likely low frequency of natural P− wasps (sensu Jandér and Herre ), would thus result in a very low probability that any single fig would contain multiple P− foundresses.…”