Fig trees (Ficus sp.) are considered as a keystone species in Singapore rainforest. This is because they flower and fruit frequently, offering frugivorous animals a year-round supply of food. The figs are actually an enclosed inflorescence known as syconium, within which a unique mutualistic relationship between the plants and fig wasps take place. Fig wasp is a tiny insect from the Agaonidae family which lays its eggs in the syconium.
Upon hatching, the larvae will grow and develop inside the syconium with protection and immediate food provided by the fig. It is also within this small syconium, the grown up wasps mate. The female wasps carrying fertilized eggs will then leave the syconium with the assistance of the wingless male wasps which chew a hole through the syconium wall and subsequently die without leaving the syconium (Cook & Rasplus, 2003).
In return for the shelter and food, the female wasps act as pollinators for the fig tree. This is because a female wasp often picks up pollen from the male flowers in its home syconium. After leaving its home syconium, the female wasp will look for another syconium to lay its eggs and eventually they pollinate the female flower within (Tan, Chou, Yeo & Ng, 2010).
The mutualistic relationship between figs tree and fig wasp is co-evolutional and highly obligated. Each fig species generally has its own agaonid symbiont as pollinator; the wasp on the other side is host-specific. This can be revealed by the inability of a fig species to colonize a new habitat without its specific pollinator wasp species being established (Ramirez, 1970). The specificity is advantageous to both fig trees and fig wasps. This is because it reduces inter-species competition for syconia while increase the chance of successful pollination of fig trees.
- William Ramirez B., 1970. Host Specificity of Fig Wasps (Agaonidae). Evolution, 24(4): 680-691.
- Cook, J.M., Rasplus, J.Y., 2003. Mutualists with attitude: coevolving fig wasps and figs. Trends in Ecology and Evolution. 18: 241-248
- Hugh Tan T.W., Chou L. M., Darren Yeo C. J, Peter Ng K. L., 2010. Primary Vegetation. The Natural Heritage of Singapore. Singapore: Pearson Education South Asia Pte Ltd.
- “Fig Wasp” by Encyclopædia Britannica, 1999. URL: http://www.britannica.com/EBchecked/topic-art/206044/19378/The-life-cycle-of-the-fig-wasp (accessed on 15 Apr 2010)
- “Bukit Timah Nature Reseve- a precious remnant of primary rainforest” by Nick Baker. Ecology Asia, 2010. URL: http://www.ecologyasia.com/html-loc/bukit-timah.htm (accessed on 14 Apr 2010)
- Wiebes, J. T., 1979. Co-Evolution of Figs and their Insect Pollinators. Annual Review of Ecology and Systematics, 10: 1-12