该文主要从物候学、行为学和生态学3个方面首次研究报道了我国西双版纳热带雨林下的一种榕树——歪叶榕(Ficus cyrtophylla)的繁殖机制。研究结果表明,歪叶榕榕小蜂(Blastophaga sp.)是歪叶榕唯一的传粉昆虫,传粉行为方式为被动传粉,而且这种榕小蜂也只能在该种榕树中成功繁衍后代。物候学观察结果表明,歪叶榕常绿且叶量常年变化较小,10~11月和3~4月是歪叶榕雄株落叶的高峰期,这时正值西双版纳的雾凉季和干热季,而雌株的落叶高峰期是3~4月;12月和5月是歪叶榕雄株新叶萌发的高峰期,而4~5月是其雌株新叶萌发的高峰期,这时正值西双版纳干热季向雨季过渡的时期,新叶萌发后同时伴随着一次该种榕树的挂果高峰期;歪叶榕在种群水平上常年持续结果,在每年的11月和4~5月有两次结果高峰期,单株每年大量结果2~3次;单棵雄株内结果异步性较高,而雌株内结果高度同步。单果进蜂数(Foundress number)为0~5只,大多数雄果(78.45%)和雌果(84.25%)只有1只传粉榕小蜂,大约16.02%的雄果和13.33%的雌果内含有2只传粉榕小蜂,其它情况均很少。在自然情况下,雄果中的总瘿花量为147.32±62.61(SD)枚,传粉榕小蜂出蜂量为110.94±62.82(SD)只,其中雌蜂多而雄蜂少,传粉榕小蜂性比为0.143 9±0.131 6(SD),瘿花形成率为64.13%±19.89%(SD),雌果中的种子数为231.44±74.25(SD)粒,种子形成率为85.72%±14.19%(SD)。歪叶榕和其传粉榕小蜂在物候学、传粉行为与花药/胚珠比(A/O ratio)和雄花成熟与其羽化出蜂的时期等方面表现出高度的相互适应。

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.