Researches On Relative Stability Of Fig-fig Wasp Mutualism In Three Dioecious Figs Of Xishuangbanna

Figs and fig wasps have always been considered as one of the classic materials on the study of co-evolution between plants and animals. Three dioecious Ficus species and their pollinators were used for experimental materials. Through the methods of artificial pollinator introduction experiments and biological microscope technology, we did studies on relative stability of fig-fig wasp mutualism in three dioecious figs of Xishuangbanna mainly at biological and ecological aspects. In addition, we measured many physiological aspects of Ficus tinctoria distributing in disturbed areas with different disturbance levels, analyzed variation of wasp community and relationship between community variation and the disturbance levels. The main research results were as follows:1, Coevolution of reproductive characteristics in three dioecious fig species and their pollinator wasps:in three dioecious Ficus species, there were no significant differences for foundress number in female figs and male figs of each species. 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 indicated that figs were generally the'controlling partner'in fig-wasp mutualism in species with large figs, but not with small figs. Compared with published studies of reproductive success in monoecious figs, the dioecious figs seemed to be more efficient in producing both seeds and wasp offspring when there were a high number of foundresses.2, Comparison of style length and reproduction success in different Ficus breeding system:The ovipositor length in monoecious figs was significantly longer than that in dioecious figs, and the coefficient variation (CV) was higher than that in dioecious figs. There was a unimodal distribution for the style length in monoecious figs, the style length CV was higher than that of pollinator ovipositor. However, the style length distributions were bimodal in two dioecious fig species, and the style length CV was also higher than the ovipositor length CV. It was more effective for monoecious figs in producing galls based on the proportions of ovaries pollinators' ovipositors could reach, but dioecious figs were more effective in producing seeds. Therefore, the hypothesis raised by Chen in 2005 was not totally correct. And more and deeper researches should be carried out if the Ficus evolution problem would be resolved.3, Disturbance effects on community structure of Ficus tinctoria fig wasps in Xishuangbanna, China:implications for the fig/fig wasp mutualism:the community comprised one pollinator species Liorrhopalum gibbosae and six non-pollinating wasp species:Sycoscapter sp.1, Philotrypesis ravii, Philotrypesis sp.1, Neosycophila omeomorpha, Sycophila sp.1, and Walkerella sp.1. More disturbed areas were characterized by higher temperatures, less shade, and more vehicle noise. The response of the fig wasp community was complex, with no simple relationship between intensity of disturbance and pollinator abundance. But the sex ratios (proportion of male progeny) of pollinators increased significantly in more disturbed area. We conclude that potential changes in fig wasp community composition brought about by disturbance, were unpredictable, with unclear consequences for tropical rainforest biodiversity.4, Variation of reproduction success in Ficus tinctoria and the implication in fig evolution:there were no significant variances for the female flowers in female or male figs for the same tree; with the increasing of the foundresses, the number and proportion of female wasp offspring significantly decreased, among these the number and proportion of female wasp offspring in natural figs were the lowest; and non-pollinators had bad impact on the number of pollinators; there were no significant variance for the number and proportion of seeds with the increasing of foundresses, the number of seeds in figs with two foundresses was the highest. And the proportion of seeds in natural figs was the lowest. Combining with the study on reproduction success Herre did about the American 12 monoecious fig species and deduction Yu et al. made, we infered that Ficus tinctoria probably was the transitional type when a part of dioecious figs deduced to monoecious fig, and it might deduce to one monoecious fig species.