天南星科植物的花多样性与传粉策略

天南星科植物具有特殊的佛焰苞花序及多样化的传粉策略, 是研究被子植物花的分化与动植物之间进化生态学联系的理想材料。本文简述了天南星科不同类型的花序结构及其传粉适应意义, 总结了天南星科传粉策略的基本类型与演化历史。天南星科的苞片结构主要包括原始型、外展平面型、直立宽佛焰苞型和直立狭佛焰苞4种类型, 呈现出从简单的片状与外展平面状结构向复杂的立体包裹状的佛焰苞结构演化的趋势。肉穗花序可分为两性花花序、单性花雌雄同序和单性花雌雄异序3种类型, 演化路线为两性花花序→单性花雌雄同序→单性花雌雄异序。天南星科的传粉者主要有鞘翅目、双翅目、膜翅目昆虫, 表现出5种主要传粉策略: 食物报酬型互利传粉、气味吸引型欺骗性传粉、交配场所型互利传粉、产卵场所型互利传粉和致死陷阱型欺骗性传粉。天南星科植物通过花序的形状、颜色、产热以及花部挥发物来吸引传粉者, 其中最主要的挥发物有二甲基硫化物、甲基吲哚化合物、萜类和苯类化合物, 模拟食物或产卵场所信号吸引鞘翅目甲虫和双翅目昆虫为其传粉。天南星科植物的佛焰苞被认为是促进该科物种分化的一个重要结构, 但该性状的演化历史及其与传粉系统分化之间的内在联系尚不明确。利用现代分子生物学技术以及模型模拟等手段, 结合生理生态学方法深入探究传粉事件与天南星科植物的花多样性以及物种分化之间的联系, 有望提升关于植物-传粉者互作与植物的花多样性分化之间关系的认识, 并丰富对被子植物多样性演化相关研究的理解。     

蝶形花亚科植物花部适应机制与传粉系统

蝶形花亚科(Papilionoideae)植物种类丰富、繁育系统多样,与其传粉者关系密切,主要表现在花部适应与传粉系统的形成。蝶形花形态复杂,为完全花,花萼、花瓣5基数,花萼呈箭头状,相邻花瓣螺旋轮生,旗瓣较大位于最外边,两片翼瓣紧贴旗瓣着生并包裹两片合生的龙骨瓣,龙骨瓣内包裹着雌、雄蕊,雌蕊位于正中央,雄蕊轮生,构成二体雄蕊(多数9+1,少数5+5)。对蝶形花亚科植物的花部特征、传粉功能群、酬物与传粉系统构建进行了回顾,重点论述了蝶形花形态和化学组成与传粉系统的进化关系以及花粉呈现机制。其中,泛化的传粉系统以蜂媒传粉为主,同时存在鸟媒传粉、蝙蝠传粉和松鼠传粉等方式,花部结构和传粉者的相互选择和相互适应推动了传粉系统的演化。花粉释放是体现蝶形花植物与其传粉功能群相互作用的重要方面,二者协同进化形成了以下4种花粉呈现机制:弹花机制、活塞机制、瓣膜机制和毛刷机制。蝶形花的花部特征与传粉功能群的相互作用形成相应的传粉系统,而传粉系统是执行传粉功能的重要集合体,各个构件的相互协调和适应保证了蝶形花亚科植物传粉过程的顺利完成。     

中国植物区系的鸟类传粉现象

概述了分布于中国的传粉鸟类类群和鸟类传粉的植物类群,并分析了这些植物的分布区类型和花部特征.中国的传粉鸟类几乎全部属于雀形目;鸟类传粉现象广泛存在于30余科的植物中,其花部特征表现出对非专性嗜蜜鸟类的适应.这些植物类群在中国的植物区系中主要表现出热带成分的特征,但其中也有温带成分.结合植物类群的系统发育研究以及对其鸟类传粉现象的认识,可以系统地了解鸟类传粉在旧世界温带地区的起源与演化,以及鸟-花协同进化的过程.     

钝叶柃不同性别花的花部形态与传粉特征比较

据有关资料记载,柃属(Eurya Thunb.)植物属于雌雄异株植物,目前仅在柃木(Eurya japonica Thunb.)中有过两性花的报道。近年的调查发现,钝叶柃(Eurya obtusifolia H.T.Chang)也有性别变异,存在两性花。在对其性别特征及功能研究的基础上,进一步跟踪了钝叶柃的开花和传粉过程,对不同性别花的花部形态和传粉特征进行了比较分析。在重庆市北碚区选取了4个样地,测定了花部形态、花朵朝向、花粉活力、柱头可授性、花粉对水的耐受性、单花花粉量和单花泌蜜体积等形态和传粉相关指标,并对其开花动态、传粉昆虫种类和昆虫传粉行为进行了仔细观察,还进行了套袋试验。结果发现钝叶柃不同性别花的花部形态和传粉特征既有一些共同点,又存在着明显差异,性别变异株则呈现出雌雄植株间的过渡特征。钝叶柃是一种花期短,花小而多,开花同步性高的植物,雌花和雄花色味相同。该植物的主要传粉方式为虫媒,主要传粉者为两种蜜蜂科昆虫,但风媒也在其传粉中起着一定作用。该植物不同性别花的主要差异有:1)雄花呈灯笼状,花瓣不反卷,雌花辐射状,花瓣反卷;2)雄花较雌花大;3)雄花倾向于垂直朝下,雌花倾向于斜向下朝向枝条末端;4)雌花寿命较雄花长。钝叶柃在开花和传粉上的许多特征都在一定程度上体现了其对雌雄异株性系统的适应。相应地,传粉者在不同性别植株上的行为也存在一定差异。钝叶柃不同性别花在形态上的差异是其周围各种生物因素及非生物因素共同作用的结果,其中传粉昆虫和雨水的选择可能在这些差异的塑造中起着重要作用。     

姜科、闭鞘姜科植物繁育系统与传粉生物学的研究进展

综述了姜科Zingiberaceae植物繁育系统和传粉生物学方面的研究及其进展。姜科有50余属1500多种,是一个泛热带分布的、动物传粉的单子叶植物大科。姜科植物中存在着雌花两性花异株、雄花两性花同株、花柱卷曲性、雄性先熟、自交不亲和等多种性表达方式和花部机制。姜科植物重要的传粉动物包括各种蜂类、天蛾、蝴蝶、鸟类等,不同的传粉动物对应不同的花部特征。在相对有限的研究中,姜科植物展现出了一些独特的传粉和繁育机制,在豆蔻属Amomum、山姜属Alpinia等植物中发现的花柱卷曲性被认为是植物界中一种独特的促进异交的行为机制,在对黄花大苞姜Caulokaempferia coenobialis的研究中发现了植物界中一种全新的花粉滑动自花传粉机制,这些新的研究和发现丰富了我们对姜科植物传粉和繁育系统多样性的认识。本文提出了今后姜科植物繁殖生物学研究的建议:对更多未知姜科植物类群的传粉和繁育系统进行研究;从系统发育的角度开展姜科不同类群植物的传粉和繁育系统的演化研究;对花柱卷曲性这一独特的性多态现象开展全面深入的研究。     

番荔枝科的抗癌植物

番荔枝科的抗癌植物宋万志马林番荔枝科植物是热带区系中主要的植物类群之一,喜生于气温较高而潮湿的林中。我国有２４属,约１０３种,资源较丰富。多年来人们仅知该科番荔枝为热带著名的水果,瓜馥木的花可提取精油,以及不多的民间药。许多种类尚未充分研究。近１０多...     

苦苣苔科镜像花的多样性及演化

泛热带分布的苦苣苔科(Gesneriaceae)在我国南方具有极高的物种丰富度与特有率,花部特征变化丰富,是研究物种形成与适应演化的代表类群。镜像花(mirror-image flowers)是极为特化的传粉系统,在苦苣苔科中出现了较多的不同类型,可能与苦苣苔科物种多样性形成与维持有关。该研究总结与分析了苦苣苔科镜像花的类型多样性以及系统分布与适应演化等,讨论了镜像花对苦苣苔科物种形成与维持的积极意义。结果表明:镜像花仅分布在亚洲和非洲的苦苣苔亚科(Didymocarpoideae)的7个属,在历史上就至少发生了5次独立起源。长冠苣苔属(Rhabdothamnopsis)、南洋苣苔属(Henckelia)及长蒴苣苔属(Didymocarpus)镜像花的花柱与可育雄蕊分别向左、右两侧偏转,形成互补镜像花;蛛毛苣苔属(Paraboea)、喜鹊苣苔属(Ornithoboea)、非洲堇属(Saintpaulia)镜像花缺乏与花柱对应侧偏的可育雄蕊(非互补镜像花);而海角苣苔属(Streptocarpus)直立堇兰亚属(subg.Streptocarpella Engler)则同时出现了互补、非互补镜像花。不同于其他被子植物(离瓣花、缺乏花冠筒),苦苣苔科中的镜像花大多伴随着明显的花冠筒、内藏的雄蕊、合生的花药,以非互补镜像花为主;传粉者以小型的无垫蜂(Amegilla spp.)和熊蜂(Bombus spp.)为主。这些特殊的花部综合征与特化的传粉机制,提高了传粉精确性,可能促进了传粉隔离与物种适应辐射。今后的一个研究重点应通过分子系统发育方法,进一步揭示苦苣苔亚科互补与非互补镜像花的进化顺序及其在物种分化与长距离扩散过程中的可能作用。     

植物气味腺研究进展

气味腺是花器官上能够产生和释放花气味的特殊腺体结构,在传粉过程中与其他花部性状结合能够吸引传粉者访花,气味腺的研究有助于揭示动物与植物之间的协同进化机制,此外,气味腺外部形态特征及细胞微形态可作为分类依据之一。对气味腺的结构、类型和检测方法,及其在植物科属中的分布情况进行了归纳总结,并对气味腺在传粉过程中和分类学上的意义进行了分析。最后提出只有结合分子实验技术手段,全面综合考虑繁殖生物学和植物化学的分析方法,才能深入理解气味腺的多样性与演化。     

鹅掌楸的传粉环境与性配置

近年来研究表明,动物传粉者对植物花部诱物特征（花冠形状大小,花蜜产量和花序大小）有潜在的选择作用。不同效率的传粉者可能导致植物性配置的变化,不同传粉效率的环境下,两性花植物鹅掌楸的花粉和胚珠的配置不同,居群Ｚ在主要访花者是传粉效率较低的类的传粉环境下,花粉粒小,花粉数量相对较高;另一方面胚珠投资的减少,缓解了低效的传粉（增大授粉的几率）,增加了受精的机会。相对而言,具有高效访花者的两个居群,资源较     

广西蜘蛛抱蛋(Aspidistra retusa)的传粉生物学研究

蜘蛛抱蛋属植物的花部结构丰富多样,且常常贴地表开花,但其传粉生物学研究鲜有报道。广西蜘蛛抱蛋(Aspidistra retusa)是广西特有植物,为揭示该物种的自然传粉机制,在蜘蛛抱蛋属世界分布和分化中心的广西境内,开展了广西蜘蛛抱蛋开花物候、访花昆虫及繁育系统的野外观测研究。结果表明:广西蜘蛛抱蛋的花部结构中雄蕊高于雌蕊,但自交不亲和,为异花传粉;双翅目瘿蚊属成虫(Cecidomyia sp.,Cecidomyiidae,Diptera)为其专性传粉者,作为回报,广西蜘蛛抱蛋为瘿蚊提供理想的交配场所,同时提供大量的花粉供雌瘿蚊取食以补充生殖所需能量,并为受精卵的孵化以及幼虫的发育提供舒适的环境。该研究用实地现场观察第一手数据验证了前人有关蜘蛛抱蛋属植物瘿蚊传粉的推测,为中国蜘蛛抱蛋属植物传粉生物学研究的首次报道,然而蜘蛛抱蛋属植物花部结构极具多样性,应存在更多样的传粉方式,还有待更深入的调查研究。     

Fly pollination and duodichogamy in Bridelia stipularis and Cleistanthus sumatranus (Phyllanthaceae)

The globally distributed family Phyllanthaceae comprises 1745 species, all of which produce unisexual flowers, and most of the species occur in the tropics. The few species in which the pollination system has been studied are pollinated by flies, wasps, or specialized moths, and at least two species are duodichogamous. Here we report on the flowering phenology and pollination of the Chinese species Bridelia stipularis and Cleistanthus sumatranus, which were studied on the tropical Hainan Island. Both species are duodichogamous and indicated to be fly‐pollinated. The calliphorid species Chrysomya megacephala, Isomyia isomyia, Pierretia sp., Hemipyrellia sp., and Achoetandrus tufifacies were the most frequent flower visitors to B. stipularis; some of these species together with syrphids (Meliscaeva cinctella, Dideopsis sp., and Eristalis sp.) were the most abundant visitors to Cl. sumatranus flowers. Fruit set in hand‐pollinated flowers was higher than in open‐pollinated flowers, but because of natural fruit abortion the difference was not significant, indicating that fly pollinators do not limit reproduction of these Phyllanthaceae species. This study provides an addition to the limited Asian literature on pollination by flies and the even more limited literature on duodichogamy. It could help to broaden our understanding for analysis of the evolution of duodichogamy in future research, but the specific ecological factors behind the evolution of this rare sexual system are still difficult to generalize.     

Evolution of a non-flying mammal-dependent pollination system in Asian Mucuna (Fabaceae)

Pollinator shifts are often related to speciation in angiosperms, and the relationship between them has been discussed in several plant taxa. Although limited information on plants pollinated by non-flying mammals in Central and South America and Africa is available, related research has not been conducted in Asia. Herein, I summarize the available knowledge of pollination in Asian Mucuna (Fabaceae), a genus mainly distributed in the tropics, and discuss the evolution of plants pollinated by non-flying mammals in Asia. Nineteen pollinator species have been recorded and pollination systems have been categorized into four types. An examination of the relationship between Mucuna species and their pollinators from the lineage perspective revealed that all species in Mucuna, subgenus Macrocarpa, which are distributed in Asia, are pollinated exclusively by non-flying mammals. Additionally, plants pollinated by non-flying mammals were found to have diverged from bat-pollinated and non-flying mammal-pollinated plants, while plants pollinated by non-flying mammals have evolved multiple times. This is a unique example of evolutionary transition. I hypothesize that the diversification of squirrel species in tropical Asia may have led to the speciation and diversification of Mucuna in Asia. Furthermore, the behavioural and ecological characteristics of bats and birds in Asia differ from the characteristics of those in other regions, implying that Asian Mucuna species do not rely on bat or bird pollinators. The adaptation of floral characteristics to pollinators is not well understood in Asia. Mammal-pollinated plants in Asia may have evolved differently from those in other regions and have unique pollination systems.     

The design of trapping devices in pollination traps of the genus Arum (Araceae) is related to insect type

Pollinators have long been known to select for floral traits, but the nature of this relationship has been little investigated in trap pollination systems. We investigated the trapping devices of 15 Arum spp. and compared them with the types of insects trapped. Most species shared a similar general design of trap chamber walls covered in downward‐pointing papillate cells, lacunose cells in the chamber wall and elongated sterile flowers partially blocking the exit of the trap. However, there was significant variation in all these morphological features between species. Furthermore, these differences related to the type of pollinator trapped. Most strikingly, species pollinated by midges had a slippery epidermal surface consisting of smaller papillae than in species pollinated by other insects. Midge‐pollinated species also had more elongated sterile flowers and tended to have a larger lacunose area. We conclude that pollination traps evolve in response to the type of insect trapped and that changes to the slippery surfaces of the chamber wall are an important and previously little recognized variable in the design of pollination traps. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 172 , 385–397.     

Flowers and Beetles in the South American Tropics

Examples of beetle pollination in the South American tropics are given. The case histories refer to representatives of the families Cyclanthaceae, Annonaceae, and Araceae. In most cases the cantharophilous syndrome does not seem to be the result of coevolution but of a one-sided adaptation of flowers to the behavior, necessities, and sense-capacities of beetle species. It is emphasized that cantharophily may not necessarily be an indication of ancientness of a flower/insect relationship. Besides primitive angiosperms, there are derived and modern groups which, in their pollination, are specialized for beetles. Carludovica palmata (Cyclanthaceae) is pollinated by small curculionids which are attracted by odors in the early morning hours. Annona coriacea (Annonaceae) and Philodendron selloum (Araceae) are pollinated by large dynastid scarab beetles in the evening hours. In all three species thermogenesis occurs. Although belonging to widely separate systematic groups, Annona flowers and Philodendron inflorescences have a similar pollination biology, which indicates that their adaptations to beetles are the result of convergent evolutionary developments.     

Pollination syndromes in a specialised plant‐pollinator interaction: does floral morphology predict pollinators in Calceolaria?

Pollination syndromes are defined as suites of floral traits evolved in response to selection imposed by a particular group of pollinators (e.g., butterflies, hummingbirds, bats). Although numerous studies demonstrated their occurrence in plants pollinated by radically different pollinators, it is less known whether it is possible to identify them within species pollinated by one functional pollinator group. In such a framework, we expect floral traits to evolve also in response to pollinator subgroups (e.g., species, genera) within that unique functional group. On this, specialised pollination systems represent appropriate case studies to test such expectations. Calceolaria is a highly diversified plant genus pollinated by oil‐collecting bees in genera Centris and Chalepogenus. Variation in floral traits in Calceolaria has recently been suggested to reflect adaptations to pollinator types. However, to date no study has explicitly tested that observation. In this paper, we quantitatively test that hypothesis by evaluating the presence of pollination syndromes within the specialised pollination system formed by several Calceolaria and their insect pollinators. To do so, we use multivariate approaches and explore the structural matching between the morphology of 10 Calceolaria taxa and that of their principal pollinators. Our results identify morphological matching between floral traits related to access to the reward and insect traits involved in oil collection, confirming the presence of pollinator syndromes in Calceolaria. From a general perspective, our findings indicate that the pollination syndrome concept can be also extended to the intra‐pollinator group level.     

Pollination syndromes predict brood-site deceptive pollination by female hoverflies in Paphiopedilum dianthum (Orchidaceae)

In order to explore the relationship between the pollinator and pollination syndromes, and to evaluate the possibility of predicting likely pollinators based on pollination syndromes, the pollination biology of Paphiopedilum dianthum was examined. This species shares a close phylogenetic relationship, similar habit, and a recognizable syndrome of floral features (including helmet-shaped labellum, big dorsal sepal, and black warts or hairs on petals) with other brood-site deceptive Paphiopedilum species. According to the pollination syndrome concept, P. dianthum would be pollinated by hoverflies and attract pollinators with brood-site deception. Results were consistent with this prediction. Paphiopedilum dianthum was mainly pollinated by female hoverflies (Episyrphus balteatus), and these flies were indeed lured by the false brood-site on the orchid flower. It is suggested that the pollination syndrome may be correlated with pollination selective pressure, but not simply with pollinator species, and that accurate prediction requires consideration of all factors influencing floral characters, including habit and evolutionary history.     

Floral closure in response to temperature and pollination in Gentiana straminea Maxim. (Gentianaceae), an alpine perennial in the Qinghai-Tibetan Plateau

Floral closure may be induced by pollination and various other factors, but is rarely studied comprehensively. Different kinds of floral closure should have various effects on reproductive fitness of plants. Two contrasting types of floral closure were observed in the flowers of Gentiana straminea Maxim. in the eastern Qinghai-Tibetan Plateau. The first type occurred prior to pollination during both gender phases, in response mainly to decreasing air temperatures. Flowers closed when decreasing temperatures approached 20°C and subsequently began to reopen the following day during mid-morning when air temperatures warmed to approximately 13–15 °C. This kind of floral closure can protect pollen grains on either stamens or stigmas, increasing fitness of both male and female. Following pollination, permanent floral closure occurred, although there was a delay between the dates of pollination and permanent closure, during which flowers continued to show temporary closure in response to low temperature episodes. The time required for permanent, pollination-induced closure varied according to the age of the gender phase, including a prolonged time before closure if pollination occurred early in the female phase. The retaining of permanent closed flowers increased both approaching (to inflorescences) and visiting (to unpollinated flowers) frequencies of individual plants when with fewer open flowers and the persisting corolla is further beneficial for seed sets of these pollinated flowers. Thus, two separate types of floral closure, one in response to environmental cues and the other in response to the age of each gender stage, appeared to have a strong influence on reproductive fitness in this species. These results revealed a different adaptive strategy of alpine plants in the sexual reproduction assurance in addition to the well-known elevated floral longevity, dominant role of more effective pollinators and increased reproduction allocation in the arid habitats.     

REPRODUCTIVE BIOLOGY OF TROPICAL LOWLAND RAIN FOREST TREES. II. POLLINATION SYSTEMS

The reproductive biology of tree species of a tropical rain forest was investigated to determine the relative frequency and spatial distribution of different types of pollination mechanisms. Species pollinated by medium-sized to large bees were most frequent, followed by those pollinated by moths, small diverse insects and small bees, in that order. Almost one half the total species were found to have pollinators with wide foraging ranges. Species pollinated by various groups of pollinators were distributed non-randomly. The greatest diversity of pollination systems was found in the subcanopy. As compared to the subcanopy, pollination mechanisms in the canopy were monotonous, consisting primarily of species pollinated by bees and small diverse insects. The hummingbird- and sphingid moth-pollinated species were found mainly in the subcanopy. The factors underlying the non-random distribution of pollinators are discussed and the potential implications of such distribution on the forest structure are explored.     

Pollination ecology of four epiphytic orchids of New Zealand

BACKGROUND AND AIMS: In New Zealand epiphytic orchids are represented by four genera and eight species. The genera Earina (three species) and Winika (one species) are the most conspicuous and widespread. These are likely to be some of the southernmost distributed genera of epiphytic orchids in the world. METHODS: To identify the pollination strategies that have evolved in these orchids, hand-pollination treatments were done and floral visitors were observed in several wild populations at two areas of southern North Island (approx. 40 degrees S). Pollen:ovule ratio and osmophores were also studied and the total carbohydrate content of the nectar produced by each species was measured. KEY RESULTS: Earina autumnalis and Earina mucronata are self-compatible, whereas Earina aestivalis and Winika cunninghamii appear to be partially self-incompatible. All four orchids are incapable of autonomous selfing and therefore completely dependent on pollinators to set fruits. Floral visitors observed in the genus Earina belong to Diptera, Coleoptera and Hymenoptera and to Diptera and Hymenoptera in W. cunninghamii. CONCLUSIONS: Contrary to many epiphytic orchids in the tropics, the orchid-pollinator relationship in these orchids is unspecialized and flowers are visited by a wide range of insects. Putative pollinators are flies of the families Bibionidae, Calliphoridae, Syrphidae and Tachinidae. All four orchids display anthecological adaptations to a myophilous pollination system such as simple flowers, well-exposed reproductive structures, easily accessed nectar and high pollen : ovule ratios.     

Repeated evolution of vertebrate pollination syndromes in a recently diverged Andean plant clade

Although specialized interactions, including those involving plants and their pollinators, are often invoked to explain high species diversity, they are rarely explored at macroevolutionary scales. We investigate the dynamic evolution of hummingbird and bat pollination syndromes in the centropogonid clade (Lobelioideae: Campanulaceae), an Andean‐centered group of ∼550 angiosperm species. We demonstrate that flowers hypothesized to be adapted to different pollinators based on flower color fall into distinct regions of morphospace, and this is validated by morphology of species with known pollinators. This supports the existence of pollination syndromes in the centropogonids, an idea corroborated by ecological studies. We further demonstrate that hummingbird pollination is ancestral, and that bat pollination has evolved ∼13 times independently, with ∼11 reversals. This convergence is associated with correlated evolution of floral traits within selective regimes corresponding to pollination syndrome. Collectively, our results suggest that floral morphological diversity is extremely labile, likely resulting from selection imposed by pollinators. Finally, even though this clade's rapid diversification is partially attributed to their association with vertebrate pollinators, we detect no difference in diversification rates between hummingbird‐ and bat‐pollinated lineages. Our study demonstrates the utility of pollination syndromes as a proxy for ecological relationships in macroevolutionary studies of certain species‐rich clades.