关键词: 榕树, 传粉榕小蜂, 繁殖生态学, 相互适应, 共生

Abstract:

Background and Aims The reproductive characteristics of fig species in the understory of tropical rainforest are rarely explored until now. Ficus cyrtophylla in Xishuangbanna tropical rainforest was chosen for a case study. We'd like to answer the following questions in this paper: 1) who is the pollen vector for F. cyrtophylla, 2) what reproductive characteristics does F. cyrtophylla have, and 3) compared with other fig species reported, what does F. cyrtophylla share with them and what is F. cyrtophylla different from them?
Methods An integrative approach combining investigation of the fig tree's phenology and its pollinator's behavior with Kruskal-Wallis tests and Mann-Whitney U tests was adopted. Data on the fig's phenology were collected by observing the sampled trees once a week from August 2004 to August 2005. The pollinator's behavior was observed at a dissecting microscope (OLMPUS-SZX12) in our lab.
Key results The results showed Blastophaga sp. was the only species-specific pollinator for F. cyrtophylla, and the passive pollinator only could produce their offspring within its figs. The range of the pollinator number trapped in the gall fig and seed fig cavity were both 0-5, and the majority (about 78.45% of gall fig and 84.25% of seed fig) had only one,other cases were very rare. For F. cyrtophylla, the fig trees were ever-green, and a little variation occurred in the quantity of the leaves. On the population level, they could continuously produce the figs year-round, synchrony within the single tree but asynchrony among the trees. The functional male tree's fruiting presented much more asynchrony than the female ones. There were two fruiting peaks in a year, November and April-May, respectively, and every tree could produce 2-3 crops in the whole year. Under the natural conditions,the mean number of galls and pollinators in every gall fig were respectively 147.32±62.61 and 110.94±62.82, the sex ratio of pollinators was 0.143 9±0.131 6, the ratio of galls per fig was 64.13%±19.89%, the mean number of seeds per seed fig was 231.44±74.25, and the ratio of seeds per fig was 85.72%±14.19%.
Conclusions The two partners in this symbiosis performed many high co-adaptations in many aspects, for example, between the pollination behavior and A/O ratio. Compared with those fig species reported until now, the reproductive ecology of F. cyrtophylla was different from them, which maybe suggest that various fig species in different geographic environment and those species with different life form in the same environment might adopt different reproductive strategies to stabilize their mutualism.

Key words: Figs, Pollinating fig wasps, Reproductive ecology, Co-adaptation, Mutualism