Variation in the phenology and population interactions between Ficus microcarpa L. f. and its pollinating wasp, Eupristina verticillata
Date Issued
2011
Date
2011
Author(s)
Yang, Hui-Wen
Abstract
In the mutualistic relationship between fig and fig wasps, the Ficus trees are pollinated exclusively by their species-specific pollinating fig wasps. How to sustain the pollinator population is a crucial issue for Ficus. This study focused on the phenological patterns between these mutualistic species and explored the adaptive reproduction strategy of a Ficus microcarpa population in Taipei, where weather varies seasonally. The study was divided into two major parts: the first section focused on fig phenology and pollinator population dynamics (Chapter two). Field surveys were conducted on 29 F. microcarpa trees in one week intervals from April 2008 to July 2009. The number of syconia in each developmental phase was recorded. The number of foundresses inside receptive syconia were counted and used as an index of pollinator population size. The results showed that temperature, solar radiation and rainfall are positively correlated with syconia abundance. Syconia abundance was highest in spring and summer, and decreased to a very low level in winter. The pollinator population exhibited a similar trend but with greater fluctuation. It reached the greatest density in summer and dropped in fall. Receptive figs are poorly pollinated in winter, and thus pollinator population should suffer a bottleneck effect during this season. The pollinator population then recovered the following spring.
The second part of this study explored the pattern of flowering asynchrony and its relationship with pollination rates, and then discussed the potential adaptive reproduction strategy of F microcarpa (Chapter 3). I used the syconia abundance data recorded in chapter one to further quantify asynchrony at the intra-tree, inter-tree and population levels. The index for chance of self-pollination (frequency of “intra-tree sexual-phase overlap”) was also counted. In addition, the difference in pollinator colonization rate was tested between trees with sexual-phase overlap and trees without. The results showed that both intra-tree asynchrony and the frequency of intra-tree sexual phase overlap were higher in spring and summer. The pollinator colonization rate was slightly (but not significantly) higher for the trees presenting sexual-phase overlap. The phenomenon of successively (>3 weeks) producing female-phase syconia was more common in spring. Finally, the strategy for F. microcarpa to overcome harsh winters and the role of asynchrony in reproductive success were discussed.
Subjects
Ficus microcarpa
Eupristina verticillata
phenology
mutualism
pollination ecology
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