慈姑花的开放式样及其花粉流

对一野生慈姑（ＳａｇｉｔａｒｉａｔｒｉｆｏｌｉａＬ．）居群的性表达状态及其花粉流散布规律进行了观测。慈姑雌雄同株,单株雄花数是雌花数的３．６倍。雌雄花单花期均为１ｄ,但二者开放式样不同。尽管雌花的数目较少,但在１ｄ内开放较多的花,其花的开放速率比雄花快。在居群水平上表现出雌雄花比例随时间大幅度波动。在传粉者进行的２６１２次访花活动中,传粉者表现出偏“雌性”访问,对每朵雌花的访问是雄花的１．４倍。用番红染色法标记慈姑的花粉运动表明,花的不同开放式样影响花粉流的散布。当雄花数占高比例时,花粉主要在邻近的个体间散布;而雄花的比例较低、雌花相对较多时,花粉远距离散布的强度加大。     

新疆荒漠植物耳叶补血草的爆发式开花式样与传粉模式

荒漠环境中干热、大风、浮尘、温度骤变等突发性天气状况,对植物的有性生殖具不利影响.耳叶补血草(Limonium otolepis)是新疆盐生荒漠的主要建群种,对其适应荒漠恶劣环境的生殖策略仍缺乏研究.为了探讨荒漠植物适应环境的开花式样和传粉模式,作者通过野外定点观测和室内电镜扫描等方法对耳叶补血草的开花进程、花部特征、传粉媒介、结实特性等进行了研究.耳叶补血草的花期在6月上旬至7月中旬,花期较长且具明显不同步的单株开花状态.在一天中,单花表现出极为集中的开花、散粉过程:一般早上8:00开始开放,9:00达开放高峰期,11:00以后基本不再有单花开放;开放后的单花持续6-8 h后闭合.每单花平均有花粉752粒,花粉表面有网状纹饰,有花蜜.传粉者主要为蜜蜂科和食蚜蝇科昆虫,访花高峰期在9:00-14:00.人工授粉实验表明耳叶补血草以异交为主,自动自花授粉率低.自然状态下结实率为36％,在花序中基部第一位上单花的结实率(45.7％)明显高于第二位上单花(3.3％).耳叶补血草爆发式开花、在短时间内快速完成传粉过程,可能是躲避荒漠环境突发性天气条件的一种策略;而居群分散的开花时间及较长的花期在应对不稳定生境,分摊生殖风险方面具重要意义.     

黄河三角洲柽柳的开花特性及传粉生态学研究

野外定位观测了柽柳(TamarixchinensisLour.)的开花物侯、开花动态、访花者的种类、行为和访花频率,并对其繁育系统、花粉-胚珠比(P/O)、花粉活力进行了检测。结果表明,柽柳单朵花的花期仅1d,P/O为390.9±81.0,繁育系统属于自交亲和、需要传粉者的类型。花的结构和开花式样适合以食蚜蝇为主的多种昆虫传粉。自然条件下的结实率为95.23%。柽柳的果实成熟期较短(15d),整个居群有长达几个月的花期,开花数目众多,因此能产生大量的种子,在适宜条件下会形成大片的柽柳灌丛。     

马先蒿属花冠形态的多样性与传粉式样的关系

马先蒿属(Pediculais)是有花植物中花冠形态多样化最为集中的属。该属主要的传粉者是熊蜂属(Bormbus)昆虫;在北美,熊蜂和蜂鸟是马先蒿植物一些种类有效的传粉者;也发现壁蜂(Osmia)为其传粉。不同的传粉机制要求某一特定的取食式样储藏和释放花粉。本文讨论了花冠类型的进化趋势与传粉式样和花粉形态的关系。传粉者的选择压力是决定花冠多样化的重要因素之一;花冠类型与传粉者和传粉行为紧密相关。马先蒿植物和传粉者的相互依赖与其花冠类型、功能和物候互相适应,但花冠类型与花粉形态两者之间似乎没有明显的一一对应关系。通过北美、日本和喜马拉雅不同地理分布马先蒿种类的比较研究表明,具有相同花冠类型的种类有着相同的传粉方式,花冠形态与传粉式样存在紧密的协同进化关系。     

锦带花的花粉活力、柱头可授性及传粉者的观察

在野外实地观测锦带花(Weigela florida(Bunge)A．DC．)的开花动态和访花者,在显微镜下观测柱头和花粉的形态及花粉-胚珠比,用TTC法测定锦带花花粉的活力,用联苯胺-过氧化氢法测定柱头可授性。结果表明,锦带花的花粉活力在开花时达70％以上,且能维持3d,之后明显下降。锦带花的柱头在开花3h后多数呈白色、二裂、具可授性,柱头的可授期持续2～3d。柱头与花药之间有5．3士0．9mm的空间距离,自然条件下难于自花授粉．开花当天7．00～10．00之间访花者最丰富,开花第2天访花者减少,开花第3天时访花者更少。在锦带花上记录到的访花者隶属于膜翅目、鳞翅目和双翅目,其中,熊蜂和蜜蜂是主要传粉者。     

开花时间与伴生种对鹤首马先蒿传粉和生殖成功的影响

开花物候是物种间相互作用的重要生活史特征和适合度因子,在全球气候变化的背景下而备受关注.为探讨开花时间如何存种内和种间水平上影响植物的传粉和生殖成功,我们连续3年(2003-2005)对不同花期和伴生种存在情况下的鹤首马先蒿(Pedicularis gruina)的传粉者访花忠实度、受粉率、坐果率、单果种子产量和果实被啃食频率进行了比较研究.结果表明鹤首马先蒿的坐果率主要受其传粉环境的影响:在没有伴生种时,不同时期鹤首马先蒿的坐果率没有显著差异,34-38％的花可以坐果;在有伴生种存在时既可以显著提高其坐果率,也可显著降低其坐果率,这取决于传粉者类型以及伴生种密穗马先蒿(P.densispica)花期的差异.密穗马先蒿具有花蜜和花粉双重报酬,在群落中可以作为主体物种吸引传粉者并间接促进与其伴生的鹤首马先蒿的传粉和生殖成功.同样无蜜的管花马先蒿(P.siphonantha)和鹤首马先蒿伴生,则是通过提高群落水平对传粉者的吸引力进而直接促进鹤首马先蒿的传粉和生殖成功.此外,研究结果也表明开花时间对坐果率没有显著影响,但是显著影响单果种子产量和果实被啃食的频率.在相同的传粉条件下早花期植株单果种子产量显著高于晚花期的种子产量,同时早花期的果实被啃食的频率显著增加.     

珍稀濒危植物猬实的开花特性与传粉生物学研究

对迁地保护的珍稀濒危植物猬实的开花动态、花粉活力、柱头可授性、访花昆虫种类、访花频率、花粉与胚珠比(P/O)、异交指数(OCI)进行观测.结果表明：猬实的单花期约为7 d,种群花期约为14 d,花冠展开后2~3 h,花粉活力达到最高,约为90％,3 d后花粉基本不具活力.在整个单花期,柱头一直具可授性,花冠展开后第2天可授性最强.花粉与胚珠比(P/O)为(398．1±63．7),异交指数(OCI)为3,表明猬实是以异交为主,自交亲和的繁育系统,有时需要传粉者完成传粉过程.猬实的访花昆虫有10余种,以膜翅目蜜蜂科和隧蜂科昆虫为主,另外还有少量双翅目食蚜蝇科昆虫,偶见鳞翅目的柑橘凤蝶和长喙天蛾,其中以蜜蜂科蜜蜂属昆虫传粉效率最高.迁地保护的猬实未见结籽,其原因还有待于进一步研究.     

叶下珠科花粉组织化学、花粉数和胚珠数及其与传粉者关系的研究

植物花粉中营养物质的储存形式以及单花的花粉数与胚珠数被认为与其传粉系统有一定的联系。本文研究了叶下珠科部分种类的花粉组织化学、花粉数和胚珠数, 以及它们与传粉者之间的关系。结果显示: 在叶下珠科内, 植物花粉所含营养成分和传粉者之间存在相关性: 蛾类传粉的类群主要属“淀粉型”花粉, 蝇类和蜂类传粉的类群主要属“非淀粉型”花粉。蝇类传粉和蛾类传粉的植物花粉数没有一定规律。蝇类传粉的类群比蛾类传粉的类群胚珠数少, 这可能是由于蝇类携带花粉能力及传粉精确性均较小, 导致植物以减少胚珠数来适应的结果。对同一属内不同生活型植物的花粉数比较, 发现乔木的单花花粉数高于灌木, 灌木的单花花粉数明显高于草本。这可能是由于不同生活型的植株, 其花朵大小不同, 导致花粉数出现明显差别。另外, 通过扫描电子显微镜对花粉形态的观察, 发现蝇类传粉的类群和蛾类传粉的类群间的花粉表面纹饰存在显著差异。     

探讨监测传粉者的方法

种子植物的有性生殖依赖于花粉传递, 传粉者是花粉传递的媒介。传粉者为野生植物和农作物提供的传粉服务, 是我们绿色星球最重要的生态过程之一, 在维持生物多样性和农作物生产方面具有重要作用。农业集约化、生境破碎、全球气候变暖等因素加剧了传粉者衰减和灭绝的风险, 对生态系统的功能和农业生产造成了不利影响。为了维系植物与传粉者生态互作关系的稳定性, 人们建立了一系列从局部地区到国际、由普通民众到科研人员参与的传粉者监测项目, 以期掌握传粉生态系统的状况和发展趋势, 为自然和农业生态系统的健康提供预警和反馈。本文强调了监测传粉者的首要前提条件, 即正确区分传粉者和访花者; 总结了监测传粉者的直接和间接方法, 包括群落水平的直接观察监测, 以及利用关联数据进行间接推断与调查; 介绍了具有潜力的由大众参与的公众监测项目。针对7种常见传粉者类群, 讨论了可行的适用于各类群的监测方法, 为监测拓展到更多的传粉者类群提供了可能。期望能为生物多样性的保护、传粉者动态的精准监测提供建议与参考。     

人工引入传粉者对油茶丰产的意义及潜在的生物安全

动物传粉在全球生态系统中提供重要服务,全球农业生产对动物传粉服务的需求稳定增长。油茶是我国特有的重要木本油料植物,栽培历史悠久,由于严格自交不亲和而高度依赖动物传粉。基于我国油茶产业发展的新形势,从资源分配和花粉限制等生态因素系统分析了油茶产量受限制的原因,提出油茶的传粉者限制效果等同于花粉限制效果,人工引入潜在的高效传粉者是解除油茶资源限制措施和传粉生态限制措施之间冲突、提高油茶产量的有效途径。论述了人工引入传粉者传粉服务的优势和挑战。对人工引入传粉者,特别是外来传粉者所面临的潜在风险和控制途径进行了梳理,提出从传粉生态服务解决油茶产量和质量问题的新思路。全文旨在为人工引入传粉者在油茶丰产中的作用提供理论与科学依据,以期促进油茶产业健康有序发展。     

Impact of insect pollinator group and floral display size on outcrossing rate

Despite the strong influence of pollination ecology on the evolution of selfing, we have little information on how distinct groups of insect pollinators influence outcrossing rate. However, differences in behavior between pollinator groups could easily influence how each group affects outcrossing rate. We examined the influence of distinct insect pollinator groups on outcrossing rate in the rocky mountain columbine, Aquilegia coerulea. The impact of population size, plant density, size of floral display, and herkogamy (spatial separation between anthers and stigmas) on outcrossing rate was also considered as these variables were previously found to affect outcrossing rate in some plant species. We quantified correlations between all independent variables and used simple and two-factor regressions to determine direct and indirect impact of each independent variable on outcrossing rate. Outcrossing rate increased significantly with hawkmoth abundance but not with the abundance of any of the other groups of floral visitors, which included bumblebees, solitary bees, syrphid flies, and muscidae. Outcrossing rate was also significantly affected by floral display size and together, hawkmoth abundance and floral display size explained 87% of the variation in outcrossing rate. None of the other independent variables directly affected the outcrossing rate. This is the first report of a significant impact of pollinator type on outcrossing rate. Hawkmoths did not visit fewer flowers per plant relative to other pollinator groups but preferred visiting female-phase flowers first on a plant. Both the behavior of pollinators and floral display size affected outcrossing rate via their impact on the level of geitonogamous (among flower) selfing. Given that geitonogamous selfing is never advantageous, the variation in outcrossing rate and maintenance of mixed mating systems in populations of A. coerulea may not require an adaptive explanation.     

Primary pollinator exclusion has divergent consequences for pollen dispersal and mating in different populations of a bird‐pollinated tree

Pollination by nectarivorous birds is predicted to result in different patterns of pollen dispersal and plant mating compared to pollination by insects. We tested the prediction that paternal genetic diversity, outcrossing rate and realized pollen dispersal will be reduced when the primary pollinator group is excluded from bird‐pollinated plants. Pollinator exclusion experiments in conjunction with paternity analysis of progeny were applied to Eucalyptus caesia Benth. (Myrtaceae), a predominantly honeyeater‐pollinated tree that is visited by native insects and the introduced Apis mellifera (Apidae). Microsatellite genotyping at 14 loci of all adult E. caesia at two populations (n = 580 and 315), followed by paternity analysis of 705 progeny, revealed contrasting results between populations. Honeyeater exclusion did not significantly impact pollen dispersal or plant mating at Mount Caroline. In contrast, at the Chiddarcooping site, the exclusion of honeyeaters led to lower outcrossing rates, a threefold reduction in the average number of sires per fruit, a decrease in intermediate‐distance mating and an increase in near‐neighbour mating. The results from Chiddarcooping suggest that bird pollination may increase paternal genetic diversity, potentially leading to higher fitness of progeny and favouring the evolution of this strategy. However, further experimentation involving additional trees and study sites is required to test this hypothesis. Alternatively, insects may be effective pollinators in some populations of bird‐adapted plants, but ineffective in others.     

Pollinator response to female and male floral display in a monoecious species and its implications for the evolution of floral dimorphism

Pollinator-mediated selection has been hypothesized as one cause of size dimorphism between female and male flowers. Flower number, ignored in studies of floral dimorphism, may interact with flower size to affect pollinator selectivity. In the present study, we explored pollinator response, and estimated pollen receipt and removal, in experimental populations of monoecious Sagittaria trifolia, in which plants were manipulated to display three, six, nine or 12 female or male flowers per plant. In this species, female flowers are smaller but have a more compressed flowering period than males, creating larger female floral displays. Overall, pollinators preferred to visit male rather than female displays of the same size. Both first visit per foraging bout and visitation rates to female displays increased with display size. However, large male displays did not show increased attractiveness to pollinators. A predicted relationship that pollen removal, rather than pollen receipt, is limited by pollinator visitation was confirmed in the experimental populations. The results suggest that the lack of selection on large male displays may affect the evolution of floral dimorphism in this species.     

The evolution of floral sonication,a pollen foraging behavior used by bees (Anthophila)

Over 22,000 species of biotically pollinated flowering plants, including some major agricultural crops, depend primarily on bees capable of floral sonication for pollination services. The ability to sonicate (“buzz”) flowers is widespread in bees but not ubiquitous. Despite the prevalence of this pollinator behavior and its importance to natural and agricultural systems, the evolutionary history of floral sonication in bees has not been previously studied. Here, we reconstruct the evolutionary history of floral sonication in bees by generating a time‐calibrated phylogeny and reconstructing ancestral states for this pollen extraction behavior. We also test the hypothesis that the ability to sonicate flowers and thereby efficiently access pollen from a diverse assemblage of plant species, led to increased diversification among sonicating bee taxa. We find that floral sonication evolved on average 45 times within bees, possibly first during the Early Cretaceous (100–145 million years ago) in the common ancestor of bees. We find that sonicating lineages are significantly more species rich than nonsonicating sister lineages when comparing sister clades, but a probabilistic structured rate permutation on phylogenies approach failed to support the hypothesis that floral sonication is a key driver of bee diversification. This study provides the evolutionary framework needed to further study how floral sonication by bees may have facilitated the spread and common evolution of angiosperm species with poricidal floral morphology.     

Types of pollen dispersal units in orchids,and their consequences for germination and fertilization

The various pollen dispersal units (PDU) found in orchids are discussed together with possible evolutionary trends and the consequences for germination and fertilization. Orchids with monad and tetrad pollen form more complex dispersal units by means of pollenkitt, elastoviscin, a callosic wall, common walls or a combination of these. Evolutionary trends include (1) from pollenkitt to elastoviscin; (2) from monad to tetrads and multiples of tetrads; (3) from partially dehydrated (<30 %) to partially hydrated (>30 %) pollen; and (4) from monad pollen to PDUs with many pollen grains. The biological consequences concern both male and female reproductive systems. Some features of the male side are present in all orchids irrespective of the pollen dispersal unit, whereas other characters are found only in orchids with pollinia; the same applies for the female counterpart. Pollen grains of orchids with pollinia germinate at least 24 h after pollination because the pollen grains/tetrads must swell and make space for the growth of pollen tubes.     

Influence of pollinator grooming on pollen‐mediated gene dispersal in Mimulus ringens (Phrymaceae)

Pollinator foraging patterns and the dynamics of pollen transport influence the quality and diversity of flowering plant mating opportunities. For species pollinated by grooming pollinators, such as bees, the amount of pollen carried between a donor flower and potential recipient flowers depends on how grooming influences pollen transfer. To investigate the relationship between grooming and pollen‐mediated gene dispersal, we studied bumblebee (Bombus fervidus) foraging behavior and resulting gene dispersal in linear arrays of Mimulus ringens. Each of the 14 plants in an array had a unique multilocus genotype, facilitating unambiguous assignment of paternity to 1050 progeny. Each plant was trimmed to a single flower so that pollinator movements could be linked directly to resulting gene dispersal patterns. Pollen‐mediated gene dispersal was very limited. More than 95% of the seeds sired by a donor flower were distributed over the first three recipient flowers in the visitation sequence. However, seeds were occasionally sired on flowers visited later in the pollinator's floral visitation sequence. Intensive grooming immediately following pollen removal from a donor flower significantly increased the decay rate of the donor flower's gene dispersal curve. These results suggest that the frequency and relative intensity of grooming can have significant effects on patterns of pollen‐mediated gene dispersal from individual pollen donors.