中国头细蛾属昆虫(鳞翅目,细蛾科)与大戟科植物互利共生关系研究进展

细蛾科头细蛾属昆虫与大戟科算盘子属、叶下珠属和黑面神属植物互利共生关系的发现为研究昆虫与植物协同演化过程提供了一个全新的模式。目前,国内对头细蛾与大戟科植物的互利共生关系了解和研究都很少。本文介绍了头细蛾的分类、生物学和形态适应;大戟科相关5属植物(算盘子属、叶下珠属、黑面神属、白饭树属和守宫木属)的生物地理学,开花生物学,花的结构与传粉系统的关系;寄主植物与传粉者的对应关系;互利共生关系的维持机制等。研究表明中国有丰富的头细蛾与大戟科植物资源,开展其互利共生关系的研究有重要科学意义。很多新的、复杂的头细蛾与大戟科植物的生态关系和大量的头细蛾种类有待我们去发现和研究。     

榕树-传粉者共生体系的协同进化与系统学研究进展及展望

 榕树-传粉者共生体系是目前植物与昆虫协同进化研究中的典型模式之一。国内外已经开展了大量的相关研究,从不同方面探讨了其特殊的一一对应的共生关系。榕树-传粉者的专一性互惠共生关系中蕴含了与系统发育有关的多因子协同进化的机理,因此,进行系统发育研究将有助于更好地揭示榕树-传粉者的协同进化历史和理解二者的专一性互惠共生关系。本文简单地介绍了目前榕树及其传粉者共生体系的研究状况之后,论述了榕树-传粉者协同进化的系统发育分子生物学研究成果。同时针对国际上在榕属植物的传统的系统与分类研究中存在的一些分歧及榕树传粉者亚科分类不匹配等问题,回顾了榕属的分类研究进展及其与传粉者的关系。最后,结合我国榕树与传粉者共生体系的研究状况对我国榕属的重新分类和系统发育研究作了展望。     

头细蛾专性授粉体系中区域性共生多样化研究

头细蛾属昆虫与叶下珠科植物互利共生体系中头细蛾复合体的区域性物种组成的具体情况是互利共生多样性研究模型选取的重要参考指标。本研究通过对全世界头细蛾属昆虫与叶下珠科植物协同进化体系中非一对一互利共生关系进行系统的整理,并对小果叶下珠Phyllanthus microcarpus、黑面神Breynia fruticosa、圆果算盘子Glochidion sphaerogynum、革叶算盘子Glochidion daltonii 4种植物相关的互利共生模式在不同分布区头细蛾物种成分以及种群动态进行研究。结果显示:在广西小果叶下珠居群上共生3种头细蛾,这3种头细蛾在同年的第一个世代只出现2种,在云南和海南小果叶下珠上全年只发现2种,而在广州目前饲养的头细蛾成虫更是仅有叔头细蛾1种;革叶算盘子在云南和四川有2种共生头细蛾,而在广西和海南均仅有1种;在海南和厦门黑面神与喙果黑面神共享2种头细蛾,而在广西和广东黑面神上仅发现1种头细蛾;圆果算盘子是目前发现共生头细蛾物种最复杂的寄主植物,在海南记载有4种头细蛾,但在云南圆果算盘子上仅发现优头细蛾1种。4种寄主植物相关的互利共生体系中头细蛾物种组成在不同的分布地均发生了不同程度的区域性共生多样化,甚至在同一地区的不同世代之间也存在着头细蛾物种数量的变化,这对于深入理解具有互利共生关系的物种间协同进化多样性形成机制具有重要的意义。     

叶下珠头细蛾与小果叶下珠互利共生的研究——生物学及系统稳定性

【目的】为了确定小果叶下珠Phyllanthus microcarpus与叶下珠头细蛾Epicephala sp.之间专性互利共生系统稳定性的增强是否主要通过彼此之间相互遏制对方对自身进行过度开采。【方法】通过对小果叶下珠上共生的叶下珠头细蛾形态及生物学的研究,记述了叶下珠头细蛾专性寄生寄主植物时的行为特性及共生双方利益得失。【结果】叶下珠头细蛾在广西一年两代,成虫的羽化数量与寄主植物雌雄花总数峰值变化同步;幼虫对小果叶下珠果实的寄生率为96%,单个果实内幼虫寄生数量1,但平均每个果实内被取食的种子为56.9%,叶下珠头细蛾低龄幼虫相对较高的死亡率限制了其对寄主种子的过度取食;果实内种子的适度保留和低龄幼虫的高死亡率是小果叶下珠-叶下珠头细蛾互利共生体系维持稳定的关键因素。【结论】小果叶下珠的表型性状出现了趋异性进化,叶下珠头细蛾与不同表型的小果叶下珠均有互利共生关系。因此,对叶下珠头细蛾形态及生物学进行详细研究有助于深入了解小果叶下珠与头细蛾共生体系物种组成多样性及进化生物学,并为探讨大戟科植物同头细蛾属昆虫协同互利共生多样性形成原因提供依据。     

叶下珠头细蛾与小果叶下珠互利共生的研究--生物学及系统稳定性

【目的】为了确定小果叶下珠 Phyllanthus microcarpus 与叶下珠头细蛾 Epicephala sp.之间专性互利共生系统稳定性的增强是否主要通过彼此之间相互遏制对方对自身进行过度开采。【方法】通过对小果叶下珠上共生的叶下珠头细蛾形态及生物学的研究,记述了叶下珠头细蛾专性寄生寄主植物时的行为特性及共生双方利益得失。【结果】叶下珠头细蛾在广西一年两代,成虫的羽化数量与寄主植物雌雄花总数峰值变化同步;幼虫对小果叶下珠果实的寄生率为96%,单个果实内幼虫寄生数量＞1,但平均每个果实内被取食的种子为56.9%,叶下珠头细蛾低龄幼虫相对较高的死亡率限制了其对寄主种子的过度取食;果实内种子的适度保留和低龄幼虫的高死亡率是小果叶下珠-叶下珠头细蛾互利共生体系维持稳定的关键因素。【结论】小果叶下珠的表型性状出现了趋异性进化,叶下珠头细蛾与不同表型的小果叶下珠均有互利共生关系。因此,对叶下珠头细蛾形态及生物学进行详细研究有助于深入了解小果叶下珠与头细蛾共生体系物种组成多样性及进化生物学,并为探讨大戟科植物同头细蛾属昆虫协同互利共生多样性形成原因提供依据。     

小果叶下珠花气味组成及其两性异型性

大戟科(Euphorbiaceae)植物小果叶下珠(Phyllanthus microcarpus)由种特异性细蛾科(Gracillariidae)昆虫头细蛾(Epicephala)专门为其传粉,具体包括:头细蛾在雄花上积极采粉,然后为雌花授粉并在其内产卵等极其不同的传粉行为。花气味在维持小果叶下珠与传粉头细蛾专性传粉互利共生关系中起着至关重要的作用。采用动态顶空吸附法分别收集小果叶下珠雌花和雄花气味,利用气相色谱-质谱(gas chromatography-mass spectrometry,GC-MS)联用技术分析鉴定其成分,并用峰面积归一法与内标法进行定量,最后通过主成分分析法比较两者间的差异性。结果表明:(1)小果叶下珠花气味中共分离出17种化合物,主要以萜类和脂肪族物质为主;顺-β-罗勒烯在雌花和雄花中含量均最高,为主要气味成分;(2)雌花气味释放量显著高于雄花;(3)雌花和雄花之间气味化学成分存在明显的差异,即具有两性异形性。初步推测花气味出现两性异形性是植物为适应传粉头细蛾极其高度特异的传粉行为(雄花采粉,雌花传粉并产卵)而选择进化的结果。     

革叶算盘子与两种头细蛾互惠共生体系的生物学研究

探索担头细蛾Epicephala duoplantaria和革叶头细蛾Epicephala daltonii共同为革叶算盘子Glochidion daltonii传粉的"一对二"协同进化模式。本文在野外观察和室内实验的基础上,对两种传粉头细蛾个体发育过程中生活习性和生活史进行详细研究并对比,记述共生双方利益得失;对比研究两种头细蛾幼虫形态特征的异同。结果表明,担头细蛾和革叶头细蛾在革叶算盘子上每年均为1个世代,幼虫和成虫的活动时间分别在2月-4月和4月-5月;革叶算盘子结实率为11.20%-27.02%,其中被蛀食率为26.47%-44.83%;果实中的种子败育率为26.03%-34.68%,种子被头细蛾蛀食率为9.29%-17.95%;平均每头幼虫消耗2.59-2.94粒种子来满足自身生长发育,每个植株留有49.53%-62.63%完好的种子,以维持互惠共生关系的稳定;产卵方式的差异导致担头细蛾的种群数量远高于革叶头细蛾;两种头细蛾的幼虫形态趋同进化但各自具有特性,这与革叶算盘子的形态特征及两种头细蛾习性有关。担头细蛾和革叶头细蛾共同为革叶算盘子传粉,形成了特殊的"一对二"协同进化互惠共生体系,推测担头细蛾是寄主转移来的传粉者,但该互惠共生体系并不稳定。     

三室算盘子寄主上弯头细蛾的生物学特性及花气味成分分析

【目的】为了从生物学和化学生态学角度探讨弯头细蛾Epicephala ancylopa和寄主三室算盘子Glochidion sp.间专性传粉的互利共生关系稳定性。【方法】本研究在野外观察和室内实验的基础上,对专性传粉育幼互利共生体系中三室算盘子、弯头细蛾生物学特性进行详细研究,探究互利共生双方利益得失;用动态顶空吸附法分别收集三室算盘子雄花和雌花气味物质,运用气相色谱-质谱联用技术(GC-MS)分析并鉴定其有效成分,用峰面积归一化与内标法定性定量;最后通过主成分分析法比较雄花和雌花之间气味化学成分的差异性。【结果】弯头细蛾在云南省普洱太阳河国家森林公园每年有1个世代,成虫和幼虫的活动时间分别在3-4月和8-10月。三室算盘子结实率为44.20%,被蛀食率为69.94%,平均每头幼虫消耗2.55枚种子来满足自身生长发育,寄主植物留有83.06%完好的种子,以维持互利共生关系的稳定。三室算盘子雌雄花气味中共鉴定出24种挥发物,主要以单萜类和倍半萜类物质为主,其中(Z)-罗勒烯和β-榄香烯两种萜类物质含量最高(分别为47.11%和22.72%),推测其是吸引弯头细蛾传粉的主要气味成分;雄花和雌花之间气味化学成分存在明显的差异,具有两性异型性。【结论】弯头细蛾通过以卵越夏和以蛹越冬对策,实现成虫发生期与三室算盘子花期的精准匹配。弯头细蛾成虫白天静伏,傍晚开始活动,三室算盘子花的气味物质也只在晚上才明显释放,且雌雄花气味化学成分的两性异型性有利于弯头细蛾辨别雌雄花,以完成采集花粉与传粉行为。该研究结果为头细蛾属昆虫与算盘子属植物专性传粉互利共生关系稳定性的维持机制提供了新的依据,也为深入开展通过触角电生理检测和生物行为实验来筛选吸引传粉头细蛾的活性物质提供了理论依据。     

榕树——传粉者共生体系的研究

榕属（Ｆｉｃｕｓ）植物与它的传粉昆虫榕小蜂之间有丰专一性的互惠共生关系,它们是动植物间历史悠久关系最密切的共生伙伴,它们在形态结构,生理功能,生活史同步上构成了榕树－传粉者共生体系并协同进化至今,本文论述了榕属植物和榕小蜂的生物学特征以及二者的相互作用,阐述了榕树－传粉者共生体系的构成,维持及其生物学意义。     

榕树及其传粉榕小蜂的系统发育和协同进化研究现状及展望

榕属(Ficus)是有花植物中最大的木本属,全世界有750多种.榕树及其传粉榕小蜂形成的种类专一的互惠共生系统,长期以来被作为研究共生系统比较生物学和协同进化的模式材料.虽然从20世纪90年代才开始对榕树一榕小蜂体系开展分子系统发育研究,但由于这个体系的特殊性和分子技术的快速发展,越来越多的学者开始利用分子学手段来研究榕一蜂共生系统的一系列生物学问题.本文总结了近年来对榕树及其传粉榕小蜂开展的系统发育及协同进化方面的研究,并分析了中国此方面的研究现状,对未来的研究趋势和前景进行了展望.     

Pollinators entering female dioecious figs: why commit suicide?

In the dioecious fig/pollinator mutualism, the female wasps that pollinate figs on female trees die without reproducing, whereas wasps that pollinate figs on male trees produce offspring. Selection should strongly favour wasps that avoid female figs and enter only male figs. Consequently, fig trees would not be pollinated and fig seed production would ultimately cease, leading to extinction of both wasp and fig. We experimentally presented pollinators in the wild (southern India) with a choice between male and female figs of a dioecious fig species, Ficus hispida L. Our results show that wasps do not systematically discriminate between sexes of F. hispida. We propose four hypotheses to explain why wasp choice has not evolved, and how a mutualism is thus maintained in which all wasps that pollinate female figs have zero fitness.     

Adaptive phenology of Ficus subpisocarpa and Ficus caulocarpa in Taipei,Taiwan

Insect pollination is the main strategy used by Angiosperm plants to transport pollen to another individual. The interaction between entomophilous plants and their pollinators is often mutualistic, with many species pairs being interdependent. In obligate pollination mutualism, the plant relies on its partner for pollination, whereas the pollen vector relies on plant resources. In the mutualism between Ficus (Moraceae) and the fig wasps (Hymenoptera, Agaonidae), the plant provides oviposition sites to its exclusive pollinator, which has an extremely short lifespan (a maximum lifespan of few days). This study examined how fig trees maintain their associated pollinator populations by conducting a 45-month phenological survey of 27 and 64 trees belonging to the species Ficus caulocarpa and F. subpisocarpa in Taipei, Taiwan. The observations indicated that the trees produce figs year-round with no clear seasonal pattern, and are not affected by meteorological factors. On average, about 30% of the trees of both species were bearing figs during the survey. The duration of the fig development was longer during the winter-spring period than during the summer-fall period. The trees displayed strong asynchrony among trees in the population but each crop was synchronous within a tree. However, after wasp emergence, crops lost their synchrony with part of the figs ripening within few days whereas some figs only ripened eight weeks later for F. subpisocarpa and four weeks later for F. caulocarpa. This study also discusses the implications of fig frugivory and mutualism.     

Restructuring of a mutualism following introduction of Australian fig trees and pollinating wasps to Europe and the USA

Figs and fig-pollinating wasps are obligate mutualists that require each other to complete sexual reproduction. However, landscapers can establish populations of fig trees outside their native ranges by propagation through exported seeds, seedlings or cuttings. Once mature, these trees could be colonized by pollinating wasps and/or various non-pollinating wasps that also develop in figs. In recent decades, the Australian endemic Ficus rubiginosa has been planted widely in the Mediterranean region and in parts of the USA. Observation of ripe fruit production suggested that a pollination mutualism has been re-established by pollinating wasps colonizing trees in the plant’s introduced range. We therefore used sampling of pollinators from mainland Spain, Tenerife and California (USA) and molecular studies to characterize the restructured mutualism and compare it with the native range. In the native range, the plant is pollinated by five wasp species that form the Pleistodontes imperialis complex. However, all wasps in the introduced ranges belonged to just one of these species (P. imperialis sp. 1). Moreover, their mtDNA diversity was close to zero and the sequences clearly link them with the native southern population of this species. None of the?>?20 non-pollinating wasp species from the native range were found in the introduced ranges. In summary, the restructured mutualism has been dramatically simplified, lacking all non-pollinating wasps and all but one pollinator species from the native range. Moreover, the one pollinator species to establish successfully shows a drastic reduction in genetic diversity relative to its source population.     

Interference Competition and High Temperatures Reduce the Virulence of Fig Wasps and Stabilize a Fig-Wasp Mutualism

Fig trees are pollinated by fig wasps, which also oviposit in female flowers. The wasp larvae gall and eat developing seeds. Although fig trees benefit from allowing wasps to oviposit, because the wasp offspring disperse pollen, figs must prevent wasps from ovipositing in all flowers, or seed production would cease, and the mutualism would go extinct. In Ficus racemosa, we find that syconia (‘figs’) that have few foundresses (ovipositing wasps) are underexploited in the summer (few seeds, few galls, many empty ovules) and are overexploited in the winter (few seeds, many galls, few empty ovules). Conversely, syconia with many foundresses produce intermediate numbers of galls and seeds, regardless of season. We use experiments to explain these patterns, and thus, to explain how this mutualism is maintained. In the hot summer, wasps suffer short lifespans and therefore fail to oviposit in many flowers. In contrast, cooler temperatures in the winter permit longer wasp lifespans, which in turn allows most flowers to be exploited by the wasps. However, even in winter, only in syconia that happen to have few foundresses are most flowers turned into galls. In syconia with higher numbers of foundresses, interference competition reduces foundress lifespans, which reduces the proportion of flowers that are galled. We further show that syconia encourage the entry of multiple foundresses by delaying ostiole closure. Taken together, these factors allow fig trees to reduce galling in the wasp-benign winter and boost galling (and pollination) in the wasp-stressing summer. Interference competition has been shown to reduce virulence in pathogenic bacteria. Our results show that interference also maintains cooperation in a classic, cooperative symbiosis, thus linking theories of virulence and mutualism. More generally, our results reveal how frequency-dependent population regulation can occur in the fig-wasp mutualism, and how a host species can ‘set the rules of the game’ to ensure mutualistic behavior in its symbionts.     

Interactions between seed predators/pollinators and their host plants: a first step towards mutualism?

The mutualisms between fig trees and their pollinator fig wasps and between yucca plants and yucca moths are spectacular examples of coevolution. The characteristics of these independently evolved mutualisms have resulted from long‐term processes, the first stages of which are unknown. A fundamental question in the study of mutualism is how these interactions evolve. Seed predator/pollinator and host plant interactions, which may initially be considered as mainly antagonistic, have the potential to provide good model systems for the study of the first stages of evolution towards mutualism. We present here theoretical models assessing the consequences of interactions between specialized seed predator insects and their host plants. These models describe the parameters that affect the fitness of an individual female seed predator and her influence on the fitness of the host plant. In an optimal strategy for the seed predator, the number of eggs laid in each flower depends on the interaction between the adult and larva survival. Along with a growing predation pressure on adults and larvae several eggs must be laid in each flower by the female seed predator to enhance her fitness. However, in a situation where the host plant selectively aborts flowers with a high number of eggs the fitness of the seed predator will seriously decrease. If the cost of selective abortion is less than the cost of seed predation the host plant will maintain fitness. In a mutualistic relationship a balance between the cost and the benefit of the parameters in the fitness models of the seed predator and the host plant has to occur so that the net seed output is larger than zero (0). Any unselfish behaviour or quality of the seed predator that would benefit the host plant in such a way that the net seed output increases might be a first stage in an interaction becoming mutualistic. The models presented here will not only provide a platform for empirical studies on interactions that may swing from parasitism to mutualism, but also for seed predator/pollinator and host plant interactions in general.     

A comparison of growth and reproduction, under laboratory conditions, of males and females of a dioecious fig tree

The interaction between Ficus spp. (Moraceae) and their pollinating wasps (Chalcidoidae: Agaonidae) is a highly co-evolved mutualism. Approximately half of all fig species are monoecious and produce a mixture of wasps and seeds within the same fig. In functionally dioecious fig trees male and female functions are separate. Figs on male trees produce wasps and pollen, whereas figs borne on female plants produce only seeds. Dioecious fig phenology provides an excellent opportunity to investigate the effect of sexual specialization on the obligate fig?Cfig wasp interaction and the non-pollinators associated with the system. Here we describe laboratory studies of phenological variation between two sexes in terms of vegetative growth and fig production in a dioecious fig tree Ficus montana. We also describe reproductive output in terms of wasp production in males and seeds in females. Intrasexual asynchrony was observed for the plants, with synchrony between the sexes with year-round production of figs. Male plants grew more rapidly, but leaf phenology was very similar. Crop sizes and development times were the same for males and females. Seasonal effects were strong for leaf phenology and fig initiation, but had a very limited effect on fig composition. The results show that the phenological differences described for other dioecious figs do not apply to all species.     

Evolution of obligate pollination mutualism in the tribe Phyllantheae (Phyllanthaceae)

The landmark discovery of obligate pollination mutualism between Glochidion plants and Epicephala moths has sparked increased interest in the pollination systems of Phyllantheae plants. In this paper I review current information on the natural history and evolutionary history of obligate pollination mutualism in Phyllantheae. Currently, an estimated >500 species are mutualistic with Epicephala moths that actively pollinate flowers and whose progeny feed on the resulting seeds. The Phyllantheae also includes species that are not mutualistic with Epicephala moths and are instead pollinated by bees and/or flies or ants. Phylogenetic analyses indicate that the mutualism evolved independently five times within Phyllantheae, whereas active pollination behavior, a key innovation in this mutualism, evolved once in Epicephala . Reversal of mutualism has occurred at least once in both partner lineages, involving a Breynia species that evolved an alternative pollination system and a derived clade of Epicephala that colonized ant-pollinated Phyllantheae hosts and thereby lost the pollinating habit. The plant–moth association is highly species specific, although a strict one-to-one assumption is not perfectly met. A comparison of plant and moth phylogenies suggests signs of parallel speciation, but partner switches have occurred repeatedly at a range of taxonomic levels. Overall, the remarkable species diversity and multiple originations of the mutualism provide excellent opportunities to address many important questions on mutualism and the coevolutionary process. Although research on the biology of the mutualism is still in its infancy, the Phyllantheae– Epicephala association holds promise as a new model system in ecology and evolutionary biology.     

The dominant exploiters of the fig/pollinator mutualism vary across continents,but their costs fall consistently on the male reproductive function of figs

1. Fig trees (Moraceae: Ficus) are keystone species, whose ecosystem function relies on an obligate mutualism with wasps (Chalcidoidea: Agaonidae) that enter fig syconia to pollinate. Each female flower produces one seed (fig female reproductive function), unless it also receives a wasp egg, in which case it supports a wasp. Fig male reproductive function requires both male flowers and pollinator offspring, which are the only vectors of fig pollen. 2. The mutualism is exploited by other wasps that lay eggs but provide no pollination service. Most of these non‐pollinating fig wasps (NPFWs) do not enter syconia, but lay eggs through the wall with long ovipositors. Some are gall‐makers, while others are parasitoids or lethal inquilines of other wasps. 3. Ficus is pan‐tropical and contains >750 fig species. However, NPFW communities vary across fig lineages and continents and their effects on the mutualism may also vary. This provides a series of natural experiments to investigate how the costs to a keystone mutualism vary geographically. 4. We made the first detailed study of the costs of NPFWs in a fig (Ficus obliqua G. Forst) from the endemic Australasian section Malvanthera. In contrast to the communities associated with section Americana in the New World, wasps from the subfamily Sycoryctinae (Chalcidoidea: Pteromalidae) dominated this community. 5. These sycoryctine wasps have a negative impact on pollinator offspring numbers, but not on seed production. Consequently, while the NPFW fauna varies greatly at high taxonomic levels across continents, we show that the consistent main effect of locally dominant exploiters of the mutualism is to reduce fig male reproductive function.     

Biased oviposition and biased survival together help resolve a fig–wasp conflict

We report evidence that helps resolve two competing explanations for stability in the mutualism between Ficus racemosa fig trees and the Ceratosolen fusciceps wasps that pollinate them. The wasps lay eggs in the tree's ovules, with each wasp larva developing at the expense of a fig seed. Upon maturity, the female wasps collect pollen and disperse to a new tree, continuing the cycle. Fig fitness is increased by producing both seeds and female wasps, whereas short‐term wasp fitness increases only with more wasps, thereby resulting in a conflict of interests. We show experimentally that wasps exploit the inner layers of ovules first (the biased oviposition explanation), which is consistent with optimal‐foraging theory. As oviposition increases, seeds in the middle layer are replaced on a one‐to‐one basis by pollinator offspring, which is also consistent with biased oviposition. Finally, in the outer layer of ovules, seeds disappear but are only partially replaced by pollinator offspring, which suggests high wasp mortality (the biased survival or ‘unbeatable seeds’ explanation). Our results therefore suggest that both biased oviposition and biased survival ensure seed production, thereby stabilizing the mutualism. We further argue that biased oviposition can maintain biased survival by selecting against wasp traits to overcome fig defenses. Finally, we report evidence suggesting that F. racemosa balances seed and wasp production at the level of the tree. Because figs are probably selected to allocate equally to male and female function, a 1:1 seed:wasp ratio suggests that fig trees are in control of the mutualism.