【作者】 张凤萍；

【导师】 杨大荣；

【作者基本信息】 中国科学院研究生院（西双版纳热带植物园） ， 生态学， 2009， 博士

【摘要】 榕树与其传粉榕小蜂互惠共生关系是昆虫与植物相互作用中关系最为密切、最具典型的传粉共生系统之一。对这个互惠系统的研究既是植物学、生态学和生物学等研究中的热点,也是揭示植物与昆虫进化的关键课题。在榕果内除了传粉榕小蜂外,还寄生着许多非传粉榕小蜂。绝大多数的非传粉榕小蜂在榕果外产卵,只有极少数隶属于Sycoecinae、Sycophaginae和Otitesellinae亚科内的榕小蜂能够通过榕果的顶生苞片进入到果腔内产卵。本文以进入果腔的非传粉榕小蜂及其寄主榕树作为研究对象,比较研究Diaziella和Lipothymus属榕小蜂在由Eupristina属榕小蜂传粉的榕树里的发生情况,不仅比较了自然种群间的关系,还增加了控制性放蜂试验来研究Eupristina、Diaziella和Lipothymus三个属榕小蜂各自的繁殖特性及其与寄主之间的作用模式,并且进一步研究了Diaziella和Lipothymus属榕小蜂由寄生演化为互惠的机制。研究的结果为探寻榕—蜂互惠关系的起源,了解其协同进化的机制提供了科学依据。主要的研究结果如下：1.通过对由Eupristina属榕小蜂传粉的10种榕树的调查,发现钝叶榕Ficus curripes和大叶水榕Ficus glaberrima寄生有进入果腔产卵的金小蜂。钝叶榕是被动传粉类型,大叶水榕、高榕、垂叶榕、劲直榕、细榕、疣枝榕、毛枕果榕和Ficus sp.的是主动传粉类型。在大青树Ficus hookeriana的榕果中,花药与胚珠比高(0.56),但是它的传粉榕小蜂有健全的花粉筐和花粉刷结构,大青树的传粉模式不确定。进入果腔产卵的金小蜂在主动和被动传粉类型的榕树中都有发生。2.进入果腔产卵的金小蜂和传粉榕小蜂在同一时间进入榕果产卵,而且主动寻找进过传粉榕小蜂的榕果进入果腔产卵。进入果腔产卵的金小蜂在被动传粉的钝叶榕中,能够为其寄主传粉。杨氏榕树金小蜂Diaziella yangi、Lipothymus sp和钝叶榕传粉榕小蜂的传粉效率均随着放入雌蜂数量的增加而增加,两种金小蜂的传粉效率有时比钝叶榕传粉榕小蜂的传粉效率还高。而在主动传粉的大叶水榕中,奇异榕树金小蜂Diaziella bizarrea不能起到传粉的作用。不管是在被动传粉还是在主动传粉类型的榕树中,进入果腔产卵的金小蜂都必须依靠传粉榕小蜂制造瘿花的寄居类,它们不能独立繁衍后代。并且对传粉榕小蜂产生负面影响,而与种子没有相关性。进入果腔产卵的金小蜂目前已经与其寄主建立了互惠关系,但还不能取代传粉榕小蜂,成为新的传粉榕小蜂,它们进化成为典型的专一的传粉者,还需要经过漫长的演化,一直演化到自己能够独立制造瘿花,才能与其寄主建立互不可缺的互惠共生关系。3.钝叶榕传粉榕小蜂和大叶水榕传粉榕小蜂雄蜂无翅,交配都发生在寄生的榕果内,属于局域配偶竞争理论。进入果腔产卵的非传粉榕小蜂的交配场所和交配行为与根据雄蜂翅型预测的结果并不完全一致。虽然杨氏榕树金小蜂和奇异榕树金小蜂雄蜂有翅,但是其大部分交配行为发生在寄生的榕果内,属于部分局域配偶竞争范畴,并且雄蜂为争夺交配的雌蜂,相互之间有打斗行为；Lipothymus sp雄蜂虽然无翅,但是有部分交配行为仍发生在寄生的榕果外,也属于部分局域配偶竞争。钝叶榕传粉榕小蜂Eupristina sp的后代平均性比显著高于雄蜂有翅型杨氏榕树金小蜂的平均性比,但与雄蜂无翅型Lipotymus sp的平均性比相比,没有显著性差异。奇异榕树金小蜂雄蜂尽管有翅,平均性比却显著低于大叶水榕传粉榕小蜂的平均性比。杨氏榕树金小蜂、奇异榕树金小蜂和(?)Lipothymus sp的平均性比与寄生榕果的比率没有明显的相关性。4.在钝叶榕和大叶水榕中,榕果中所有的花柱柱头都呈游离状的分布,雌花间的花柱柱头没有交织连接在一起形成联合柱头(Syn-stigma)。正在产卵的传粉榕小蜂寻找合适的插入位点是在柱头和花柱之间,而不是从柱头的顶端。5.通过对大叶水榕传粉榕小蜂和榕果内的种子在2006年、2007年和2008年中数量的比较,发现二者之间没有明显的相关性。传粉榕小蜂在2006年12月份的后代数量显著高于2007年8月份和2008年7月份的后代数量,但是奇异榕树金小蜂的后代数量在这三年中没有显著性差异。奇异榕树金小蜂、Svcoscapier sp和(?)Phlotrypesis sp.(?)这三种榕小蜂每年都有出现,这暗示着一些榕小蜂呈现出季节性重现或专一性。另外,榕小蜂的群落结构没有显著地受季节因素变化的影响。6.钝叶榕和大叶水榕与其传粉者之间是高度专一的互惠共生关系,而且双方在物候学、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都表现出高度的相互适应；与其它榕树相异之处在于,钝叶榕除了专一的传粉榕小蜂为其传粉以外,还有两种进入果腔产卵的金小蜂也能为其传粉。钝叶榕和大叶水榕树内结果高度同步。7.钝叶榕和大叶水榕中的非传粉榕小蜂通过各自产卵时序和幼虫食性分化的繁殖策略来分配榕果中的资源来实现自身的繁殖。非传粉榕小蜂与传粉榕小蜂的数量变化显著呈负相关。但非传粉榕小蜂和榕果内的种子没有相关性。8.在雄花期时,大叶水榕榕果内靠近果腔的传粉榕小蜂瘿花子房长度和传粉榕小蜂个体都显著大于靠近果壁层；而靠近果腔的种子显著小于靠近果壁层；靠近果腔的种子萌发率低,并且萌发速度慢；而靠近果壁层的种子萌发率高,并且萌发速度快。传粉榕小蜂更倾向于将卵产在靠近果腔的雌花中,利于后代的发育和生长。而靠近果壁的雌花则形成种子,这样利于种子的发育和萌发,从而也利于榕树的繁殖。更多还原

【Abstract】 The interaction between fig trees (Ficus) and their pollinating fig wasps (Agaonidae) represents a remarkable example of mutualism and coevolution, each needing the other for reproduction. In addition of pollinating fig wasp species, figs host a suite of parasites of the mutualism belonging to other chalcidoid families. As with the agaonids, these fig wasps develop in fig flowers, but do not usually pollinate their hosts, hence they are commonly called non-pollinating fig wasps (NPFW). Most non-agaonid wasps oviposit through the fig wall from outside the fig. A small number of non-agaonid fig wasps (subfamilies Sycoecinae. Sycophaginae and Otitesellinae) are exceptional in that, like agaonids. These non-pollinating fig wasp species do not belong in the agaonid lineage. They have foundresses that enter the figs and oviposit in the female flowers, just as agaonid wasps do. Here, we report occurrence of internally ovipositing wasps in genus Eupristina poliinated fig species. And we conduct experimental introductions in order to study the reproductive ecology and the relationships between the host figs (Ficus curtipes and Ficus glaberrima), their regular agaonid pollinators Eupristina spp.. and the internally oviposting non-agaonid wasps( Diaziella yangi, Diaziella bizarrea and Lipothymus sp.). Furthermore, the mechanism of the evolution from parasite to mutualism in parasitic lineages of the fig-wasp interaction is studied. These results are very useful for understanding the origin of the fig-fig wasp mutualism. The main results are as follows.1. Two species of figs (Ficus curtipes and Ficus glaberrima) that are pollinated by genus Eupristina also host specific fig wasps belonging to the chalcidoid genera Diaziella (S ycoecinae) and Lipothymus (Otitesellinae) among ten species of figs observed. F. curtipes is passively pollinated. Other eight Ficus species (Ficus glaberrrima, F. altissima, F. benjamina, F. stricta, F. microcarpa, F. macellandi, Ficus sp. and F. drupacea pubescens) are actively pollinated. The anther-to-ovule ratio of F. hookeriana is high (0.56), but its corresponding pollinating fig wasps have well defined thoracic pollen pockets (to carry pollen) and coxal combs on their fore coxae (to manipulate pollen). So pollination mode of F. hookeriana is not confirmed now. Internally ovipositing non-agaonids occur both in passively and actively pollinated Ficus species.2. Internally ovipositing non-agaonids and pollinating fig wasps enter figs and oviposit in the same time (female flower phase). Their females do actively seek out figs entered by Eupristina spp.. Internally oviposting non-agaonids Diaziella yangi and Lipothymus sp. can pollinate in passively pollinated F. curtipes. As the number of conspecific foundresses per fruit increased, the number of seeds produced increased. Sometimes the pollination efficiency of D. yangi and Lipolhymus sp. was even higher than that of Eupristina sp.. D. bizarrea can not be a similarly effective pollinator of Ficus glaberrima. an actively pollinated monoecious fig tree. Internally ovipositing non-agaonids failed to reproduce independently in passively or actively pollinated Ficus species, they depend on the agaonid, Eupristina, to make galls. Both species of fig-entering non-agaonid wasps significantly reduced the number of regular pollinators emerging from mature figs but had no effect on seed production. Internally ovipositing non-agaonid fig wasps have built the mutualism with their hosts, but they can not replace the regular pollinating fig wasps. As far as these internally ovipositing non-agaonid fig wasps can make galls, they can constitute the species-specific mutualism.3. The mating mode of internally non-agaonids was not identical to the results thoroughly predicted by wing morphs of males. Although they are winged, most of Diaziella yangi and D. bizarrea mated inside the figs in which they developed, and males had intensely fighting behavior for mating opportunities. On the contrary, although Lipothymus sp. was wingless, part of mates occurred outside the figs. These internally ovipositing non-agaonids followed the partial local mate competition. All the mates of regular pollinators with wingless males occurred inside the figs in which they developed, which followed LMC (Local Mate Competition). This showed that it was inaccurate to predict the mating mode only according to male morphs. The average sex ratio of the pollinator(Eupristina sp.) of F. curtipes was significantly higher than the average sex raio of D. yangi. However, there was no significantly difference between the average sex ratio of Eupristina sp. and Lipothymus sp, and there was no also significantly difference between the average sex ratio of D. yangi and Lipothymus sp. The average sex ratio of the pollinator (Eupristina sp.) of F. glaberrima was significantly higher than the average sex ratio of D. bizarrea. And there were not significant positive correlations between the averge sex ratio of three internally ovipositing non-agaonids (D. yangi, D. bizarrea and Lipothymus sp.) and the proportion of fruit in which it occurred.4. Figs of the monoecious fig trees Ficus curtipes and F. glaberrima (subsection Conosycea) lack a synstigma. which is replaced by an irregular mass of elongate stigmas. The pollinators of F. curtipes and F. glaberrima do not oviposit via the top of the stigmas, but insert their ovipositors through the stigmal bases. Oviposition behavior in fig wasps is therefore responsive to variation in floral structure within their host figs.5. Eupristina sp. progeny was not correlated with seeds in the three years (2006.2007 and 2008). The number of Eupristina sp. progeny per fig during the colder month (December 2006) was significantly higher than during the wanner month (August 2007; July 2008) (LSD:P< 0.05). There was no significant difference in the number of Diaziella bizarrea progeny during three years. D. bizarrea. Sycoscapier sp.. and Philotrypesis sp. occurred consistently.as the most common fig wasps every year. This result suggested that some fig wasps showed a certain degree of season recurrence or specificity, and the composition of fig wasps was not conspicuously influenced by the seasonal factor.6. Compared with the fig trees reported, the two partners in Ficus curiipes and F. glaberrima were also highly co-adapted in many aspects, for example, phenology, between the pollination behavior and A/O ratio, etc. In Ficus curtipes, in addition to regular pollinating fig wasp, it hosts two internally oviopositing non-agaonid fig wasps, they can pollinate for F. curtipes. F. curtipes and F. glaberrima often produced more same-phase syconia within one tree.7. For Ficus curtipes and F. glaberrima, non-pollinating fig wasps allocate resources through differentiation in oviposition time and larval diet. The non-pollinating fig wasps had significantly negative effects on pollinating fig wasps, but there were no correlations between the number of pollinating fig wasps and the number of seeds.8. At post-floral phase of syconia of Ficus glaberrima, wasp offspring and galler near the cavity were larger; wasp offspring and galler near the wall were smaller. Seeds near the wall were larger, and germination rate were higher and faster, while seeds near the cavity were smaller, and germination rate were lower and slower. Wasps prefer to oviposit in the female flowers near fig cavity to benefit the development of offspring. While female flowers near the wall were more likely to receive pollens to benefit the development and germination of seeds.更多还原