侧穗凤仙花的传粉生态和繁育系统

通过对峨眉山特有种侧穗凤仙花的开花生物学特性、花器官结构、传粉者种类和访花行为、繁育系统、花粉胚珠比(P/O)及花粉活力的研究.发现居群之间花的寿命变化比较大,它们的雄蕊期长,雌/雄蕊期比为0.12～0.17;花粉胚珠比达到4.6万,花粉在开花第一天有很高的活力(＞90%);传粉者为熊蜂和天蛾,熊蜂包括贞洁熊蜂、白背熊...     

Pollination Ecology of Pedicularis punctata Decne. (Scrophulariaceae) in the Kashmir Himalaya

Abstract The pollination ecology of Pedicularis punctata was studied in the Pir Panjal Range of the Kashmir Himalaya in the summer of 1989. Its nectarless, rostrate, long-tubed flower was found to be pollinated exclusively by Bombus foragers vibrating pollen while the stigma contacted pollen in the pollinator's cervical crevice. Workers of Bombus tunicatus and B. flavothoracicus comprised 95% of its pollinators. Pollen-foraging fidelity of its pollinators was greatest where diversity of Bombus -pollinated plant species in three plant communities was least. Foragers on other plants carried virtually no Pedicularis pollen. P. punctata is a mid-season blooming species similar in its pollination syndrome to comparable species in other geographic regions. The enigmatic function of its long, nectarless corolla tube, even more exaggerated in other Asiatic species, requires further investigation.     

牛耳朵传粉生物学研究

苦苣苔科(Gesneriaceae)报春苣苔属(Primulina Hance)是一个近年来备受关注的类群,其纷繁复杂的物种多样性和属下种间的特有分布引起了分类学家和植物学研究者的极大兴趣。该属除了极少数的物种如牛耳朵[(Primulina eburnea (Hance) Y. Z. Wang)]以外,绝大部分的物种为狭域分布或地方特有种,其分布范围很窄。为了揭示牛耳朵的传粉生物学和繁育系统对其生殖过程和拓殖能力的影响机制,作者系统地研究了牛耳朵的开花物候、花粉与柱头活性、访花昆虫的种类和访花行为、花粉胚珠比、OCI指数和套袋实验结实率,探究其传粉等生殖过程对牛耳朵的广布是否有正面影响。结果表明:牛耳朵的自然花期是3—5月,全花期约45 d,其中盛花期约20 d,单花期6～8 d;开花后1～2 d花粉活力最强,开花前柱头没有可授性;花粉胚珠比为537;杂交指数为5;去雌套袋、去雄套袋均无法结实,说明本种不存在无融合生殖;与自然授粉相比,自花授粉结实率略低,异花授粉结实率略高,说明自交亲和;牛耳朵的主要传粉者是花条蜂(Anthophora florea)和熊蜂(Bombus sp.)。花蜜产量较高、花粉量较大、花粉活力较强等特点,有利于牛耳朵完成传粉和结实的整个繁殖过程。因此,这一结果显然有利于牛耳朵的拓殖进而广布在我国华南至西南地区的喀斯特地区。     

牛耳朵传粉生物学研究

苦苣苔科(Gesneriaceae)报春苣苔属(Primulina Hance)是一个近年来备受关注的类群,其纷繁复杂的物种多样性和属下种间的特有分布引起了分类学家和植物学研究者的极大兴趣。该属除了极少数的物种如牛耳朵[(Primulina eburnea(Hance)Y. Z. Wang)]以外,绝大部分的物种为狭域分布或地方特有种,其分布范围很窄。为了揭示牛耳朵的传粉生物学和繁育系统对其生殖过程和拓殖能力的影响机制,作者系统地研究了牛耳朵的开花物候、花粉与柱头活性、访花昆虫的种类和访花行为、花粉胚珠比、OCI指数和套袋实验结实率,探究其传粉等生殖过程对牛耳朵的广布是否有正面影响。结果表明:牛耳朵的自然花期是3—5月,全花期约45 d,其中盛花期约20 d,单花期6～8 d; 开花后1～2 d花粉活力最强,开花前柱头没有可授性; 花粉胚珠比为537; 杂交指数为5; 去雌套袋、去雄套袋均无法结实,说明本种不存在无融合生殖; 与自然授粉相比,自花授粉结实率略低,异花授粉结实率略高,说明自交亲和; 牛耳朵的主要传粉者是花条蜂(Anthophora florea)和熊蜂(Bombus sp.)。花蜜产量较高、花粉量较大、花粉活力较强等特点,有利于牛耳朵完成传粉和结实的整个繁殖过程。因此,这一结果显然有利于牛耳朵的拓殖进而广布在我国华南至西南地区的喀斯特地区。     

Interspecific pollen transfer between two coflowering species was minimized by bumblebee fidelity and differential pollen placement on the bumblebee body

Aims When sympatric flowering plant species in a natural community share pollinators, study of plant–plant interactions via interspecific pollen transfer (IPT) is essential for understanding species coexistence. However, little is known about the extent of IPT between interactive species and its causes.Methods To explore how sympatric flowering plants sharing pollinators minimize deleterious effects of IPT, we investigated the pollination ecology of two endemic species, Salvia przewalskii and Delphinium yuanum, in an alpine meadow in the Hengduan Mountains, southwest China. We quantified conspecific and interspecific visits by shared bumblebee pollinators, amounts of pollen placed on different body sites of the pollinators and stigmatic pollen loads on open-pollinated flowers. To examine whether IPT affects female fitness, we measured pollen germination and seed production in the two species in an artificial pollination experiment.Important findings One bumblebee species, Bombus trifasciatus, was found to be the sole effective pollinator for the two coflowering species. Pollination experiments indicated that deposition of heterospecific pollen could significantly decrease seed set in both species. Experiments showed that S. przewalskii pollen could germinate well on stigmas of D. yuanum, inhibiting conspecific pollen germination in D. yuanum. However, seed set was not lower under open pollination than under cross-pollination within species, suggesting that no female fitness loss was caused by IPT. In foraging bouts with pollinator switches, switches from S. przewalskii to D. yuanum were relatively more frequent (8.27%) than the converse (1.72%). However, IPT from S. przewalskii to D. yuanum accounted for only 1.82% of total stigmatic pollen loads while the reverse IPT to S. przewalskii was 8.70%, indicating that more switches of bumblebees to D. yuanum did not result in higher IPT. By contrast, selection for reduced IPT to S. przewalskii would limit pollinator switches from D. yuanum. We found that a bumblebee generally carried pollen grains from both species but the two species differed in the position of pollen placement on the bumblebee's body; S. przewalskii ' s pollen was concentrated on the dorsal thorax while D. yuanum ' s pollen was concentrated ventrally on the head. This differential pollen placement along with pollinator fidelity largely reduced IPT between the two species with a shared pollinator.     

The efficiency of insect pollination of the neophyte Impatiens glandulifera (Balsaminaceae)

To comprehend the reproductional success of Impatiens glandulifera in Central Europe, the pollination system was analyzed under field conditions. Impatiens glandulifera attracts a lot of visitors because of its abundant amount of nectar with its high sugar content. The range of visitors, their composition and their changes during the blooming time and their pollen loading capacity were investigated as well as plant and flower morphology, the nectar production, the quantity and viability of pollen, the stigmatic pollen load, the pollen/ovule ratio and the seed production of the neophyte. The visitors, which in Central Europe almost exclusively utilize the nectar, are passively covered with pollen because of the morphology and the mobile suspension of the flowers. Consequently the next landing results in a pollination of I. glandulifera during the female blooming phase. Although the germination rate of the pollen deposited on the stigma is very low, a 100% seed set is readily obtained during the initial visit to a flower in female stage.     

Floral specialization for different pollinators and divergent use of the same pollinator among co‐occurring Impatiens species (Balsaminaceae) from Southeast Asia

Floral variation among closely related species is thought to often reflect differences in pollination systems. Flowers of the large genus Impatiens are characterized by extensive variation in colour, shape and size and in anther and stigma positioning, but studies of their pollination ecology are scarce and most lack a comparative context. Consequently, the function of floral diversity in Impatiens remains enigmatic. This study documents floral variation and pollination of seven co‐occurring Impatiens spp. in the Southeast Asian diversity hotspot. To assess whether floral trait variation reflects specialization for different pollination systems, we tested whether species depend on pollinators for reproduction, identified animals that visit flowers, determined whether these visitors play a role in pollination and quantified and compared key floral traits, including floral dimensions and nectar characteristics. Experimental exclusion of insects decreased fruit and seed set significantly for all species except I. muscicola, which also received almost no visits from animals. Most species received visits from several animals, including bees, birds, butterflies and hawkmoths, only a subset of which were effective pollinators. Impatiens psittacina, I. kerriae, I. racemosa and I. daraneenae were pollinated by bees, primarily Bombus haemorrhoidalis. Impatiens chiangdaoensis and I. santisukii had bimodal pollination systems which combined bee and lepidopteran pollination. Floral traits differed significantly among species with different pollination systems. Autogamous flowers were small and spurless, and did not produce nectar; bee‐pollinated flowers had short spurs and large floral chambers with a wide entrance; and bimodally bee‐ and lepidopteran‐pollinated species had long spurs and a small floral chamber with a narrow entrance. Nectar‐producing species with different pollination systems did not differ in nectar volume and sugar concentration. Despite the high frequency of bee pollination in co‐occurring species, individuals with a morphology suggestive of hybrid origin were rare. Variation in floral architecture, including various forms of corolla asymmetry, facilitates distinct, species‐specific pollen‐placement on visiting bees. Our results show that floral morphological diversity among Impatiens spp. is associated with both differences in functional pollinator groups and divergent use of the same pollinator. Non‐homologous mechanisms of floral asymmetry are consistent with repeated independent evolution, suggesting that competitive interactions among species with the same pollination system have been an important driver of floral variation among Impatiens spp.     

The Abundance and Pollen Foraging Behaviour of Bumble Bees in Relation to Population Size of Whortleberry (Vaccinium uliginosum)

Habitat fragmentation can have severe effects on plant pollinator interactions, for example changing the foraging behaviour of pollinators. To date, the impact of plant population size on pollen collection by pollinators has not yet been investigated. From 2008 to 2010, we monitored nine bumble bee species (Bombus campestris, Bombus hortorum s.l., Bombus hypnorum, Bombus lapidarius, Bombus pascuorum, Bombus pratorum, Bombus soroensis, Bombus terrestris s.l., Bombus vestalis s.l.) on Vaccinium uliginosum (Ericaceae) in up to nine populations in Belgium ranging in size from 80 m² to over 3.1 ha. Bumble bee abundance declined with decreasing plant population size, and especially the proportion of individuals of large bumble bee species diminished in smaller populations. The most remarkable and novel observation was that bumble bees seemed to switch foraging behaviour according to population size: while they collected both pollen and nectar in large populations, they largely neglected pollen collection in small populations. This pattern was due to large bumble bee species, which seem thus to be more likely to suffer from pollen shortages in smaller habitat fragments. Comparing pollen loads of bumble bees we found that fidelity to V. uliginosum pollen did not depend on plant population size but rather on the extent shrub cover and/or openness of the site. Bumble bees collected pollen only from three plant species (V. uliginosum, Sorbus aucuparia and Cytisus scoparius). We also did not discover any pollination limitation of V. uliginosum in small populations. We conclude that habitat fragmentation might not immediately threaten the pollination of V. uliginosum, nevertheless, it provides important nectar and pollen resources for bumble bees and declining populations of this plant could have negative effects for its pollinators. The finding that large bumble bee species abandon pollen collection when plant populations become small is of interest when considering plant and bumble bee conservation.     

Reproductive system and fitness of Vriesea friburgensis,a self‐sterile bromeliad species

Reproductive biology and plant fertility are directly related to many aspects of plant evolution and conservation biology. Vriesea friburgensis is an epiphytic and terrestrial bromeliad endemic to the Brazilian Atlantic rainforest. Hand‐pollination experiments were used to examine the reproductive system in a wild population of V. friburgensis. Plant fertility was assigned considering flower production, fruit and seed set, seed germination, and pollen viability. Self‐sterility observed from spontaneous selfing and manual self‐pollination treatments may be the consequence of late‐acting self‐incompatibility. Hand‐pollination results indicated no pollen limitation in the population studied. Floral biology features such as a few daily open flowers, nectar production, and sugar concentration corroborate hummingbirds as effective pollinators, although bees were also documented as pollinators. Components of fitness such as high flower, fruit, and seed production together with high seed and pollen viability indicate that this wild population is viable. From a conservation point of view, we highlight that this self‐sterile species depends on pollinator services to maintain its population fitness and viability through cross‐pollination. Currently, pollinators are not limited in this population of V. friburgensis. Conversely, the maintenance and continuous conservation of this community is essential for preserving this plant–pollinator mutualism.     

海南三七（姜科）的食源性欺骗传粉

有花植物为繁殖成功,进化出各种各样的花部特征来吸引传粉者,如为传粉者提供花蜜、花粉、栖息地等,然而在33科146属的被子植物中也存在着不提供任何报酬而欺骗昆虫为其传粉的现象。这种欺骗性传粉模式主要出现在高度进化的具有多样化传粉模式的兰科植物中。报道了在姜科植物中首次发现的食源性欺骗传粉模式。对姜科山柰属海南三七进行连续2年的传粉生物学观察和研究发现,海南三七的花在早上5:30～6:00之间开放,下午17:00～18:00左右闭合萎蔫,持续大约11～12h。开花过程中花粉活性与柱头可受性均保持较高水平(>90%)。花粉/胚珠比率(P/O)为82.20±47.89(n=20)。木蜂是其主要的访花和传粉昆虫,访花目的是吸取花蜜。海南三七虽有细长线形的蜜腺,但并不分泌花蜜作为传粉昆虫访花的报酬,采用食源性欺骗的方式欺骗木蜂为其传粉。繁育系统的研究表明广西弄化的海南三七居群主要是通过根茎进行无性繁殖。     

Autogamy in Boronia falcifolia: consequences for inbreeding and persistence in fragmented coastal heaths

Coastal heath is becoming increasingly fragmented, resulting in reduced pollinator abundance affecting species viability. The reproductive ecology and inbreeding of a common coastal heath species, Boronia falcifolia (Rutaceae), was investigated. Pollination observations and experiments were carried out at one site, and inbreeding was assessed using genetic markers at eight populations. Four pollination treatments were assessed: cross-pollination, self-pollination, autogamous pollination and open (insect) pollination. Boronia falcifolia was found to be highly self-compatible, frequently setting seeds from autogamous pollination. There were no significant differences between the autogamous, self and cross pollen treatments for any measures of reproductive success (pollen tube growth, fruit set, swollen locules and seed production). Insect activity resulted in fewer seeds per fruit than hand cross pollination, although pollinator visits were few. All populations studied were highly inbred. Autogamous self-pollination is widespread in B. falcifolia and this combined with its ability to vegetatively regenerate enhances its potential for survival when pollinators are few.     

Reproductive biology of the invasive exotic shrub, Rhododendron ponticum L. (Ericaceae)

The reproductive biology of an exotic species will affect its ability to become naturalized and invasive in non-native habitats. Rhododendron ponticum is an ecologically damaging exotic weed in the British Isles, which spreads predominantly by seed. I investigated how inbreeding and outcrossing affect seed production and germination in a wild population of this species in Ireland. Experimental manipulations revealed low fruit and seed set when insects were excluded from flowers, suggesting that this species has limited capability for spontaneous autogamy. Hand-pollination treatments showed that, although flowers are self-compatible (with self and same plant pollen), higher levels of seed set occur following outcrossing (xenogamy). There was no significant difference in rate of germination of seeds from inbred or outcrossed treatments. The addition of xenogamous pollen to open flowers did not increase fruit or seed set, suggesting that flowers in this population are not pollen limited: native generalist pollinators, mainly bumblebees ( Bombus spp.), are providing an adequate pollinator service. This work demonstrates that outcrossing increases seed set and pollinators are required to facilitate this. Hence, generalist native pollinators can promote invasion by exotic plants. Native pollinators can clearly play an important part in alien species invasion.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 373–381.     

Beyond the pollination syndrome: nectar ecology and the role of diurnal and nocturnal pollinators in the reproductive success of Inga sessilis (Fabaceae)

Inga species present brush‐type flower morphology allowing them to be visited by distinct groups of pollinators. Nectar features in relation to the main pollinators have seldom been studied in this genus. To test the hypothesis of floral adaptation to both diurnal and nocturnal pollinators, we studied the pollination ecology of Inga sessilis, with emphasis on the nectar secretion patterns, effects of sequential removals on nectar production, sugar composition and the role of diurnal and nocturnal pollinators in its reproductive success. Inga sessilis is self‐incompatible and pollinated by hummingbirds, hawkmoths and bats. Fruit set under natural conditions is very low despite the fact that most stigmas receive polyads with sufficient pollen to fertilise all ovules in a flower. Nectar secretion starts in the bud stage and flowers continually secreting nectar for a period of 8 h. Flowers actively reabsorbed the nectar a few hours before senescence. Sugar production increased after nectar removal, especially when flowers were drained during the night. Nectar sugar composition changed over flower life span, from sucrose‐dominant (just after flower opening, when hummingbirds were the main visitors) to hexose‐rich (throughout the night, when bats and hawkmoths were the main visitors). Diurnal pollinators contributed less than nocturnal ones to fruit production, but the former were more constant and reliable visitors through time. Our results indicate I. sessilis has floral adaptations, beyond the morphology, that encompass both diurnal and nocturnal pollinator requirements, suggesting a complementary and mixed pollination system.     

Pollination ecology of Gentianella uliginosa, a rare annual of the Dutch coastal dunes

The pollination ecology of Gentianella uliginosa , a rare annual in The Netherlands, was studied in three relatively small coastal dune populations. In all populations, the species was fully self-compatible: manual self pollination resulted in a seed set of 92–94%. Autofertility was also high (seed set of caged, unhandled flowers 80–85%). The homogamous flowers were visited by Bombus pascuorum , which collected nectar and transported pollen sternotribically. Differences among populations in bumblebee visitation rate did not affect natural seed set. In one plot, seed set following natural pollination was lower than after manual selñng, and as high as after spontaneous selñng. As flowers here were also visited frequently, this might be due to pollen limitation through heterospecific pollen competition. Support for this hypothesis was derived from another population, where seed set after natural pollination was lower in a plot dominated by co-flowering Mentha aquatica than in a plot with few Mentha. However, differences in water availability might also have caused this. In one population, seed sets of the cross pollination and spontaneous selfing treatments were lower than those of the manual selñng and natural pollination treatments. Whether the low outcrossing success can be attributed to small differences in the treatment of the experimental plants or to outcrossing depression remains unclear. We conclude that this annual species is most likely a predominant selfer. Its high autofertility is probably an adaptation to its wet dune slack habitat, where reproductive assurance may be important to cope with unpredictable fluctuations in water table, summer droughts and pollinator service.     

Foraging behavior affects pollen removal and deposition in Impatiens capensis (Balsaminaceae)

Flowers of most plant species are visited by a variety of animals. Some of these visitors are effective pollinators while others remove resources without transferring pollen. Studies comparing the effectiveness of different visitors as pollinators often compare taxa without considering variation in behavior within a taxon. Wilson and Thomson (Ecology 72: 1503-1507, 1991) documented the effects of honey bees and bumble bees on the pollination dynamics of Impatiens capensis. They found that pollen-collecting honey bees removed large numbers of pollen grains from anthers but deposited little of it on stigmas; bumble bees, which sought nectar, removed less pollen but deposited more of it on stigmas. It is unclear whether the low pollen transfer efficiencies of honey bees are explained by their morphology or by their pollen-collecting behavior. We repeated the work of Wilson and Thomson at a site where honey bees were foraging for nectar, not pollen. We measured the quantity of pollen remaining in anthers, the number of pollen grains deposited on stigmas, and seed production after single visits by honey bees and bumble bees. The differences between the taxa disappeared when they were foraging in a similar manner. Our results clearly demonstrate the importance of foraging behavior on the pollination effectiveness of floral visitors.     

Passerine Pollination of Rhodoleia championii (Hamamelidaceae) in Subtropical China

The pollination ecology and breeding system of the Hamamelidaceae tree species Rhodoleia championii were studied in an evergreen broad-leaved forest in Nankunshan National Forest in Guangdong Province in China. Rhodoleia championii produces lipid-rich pollen grains and dilute nectar (averaging 0.7 mL/d and 9% sugar), with nectar production peaking before 0800 h; the species is self-incompatible and does not set seed asexually. Seven species of nectar-foraging birds visited the inflorescences, with the most common visitors being Japanese white-eyes (Zosterops japonicus, Zosteropidae) and fork-tailed sunbirds (Aethopyga christinae, Nectariniidae). Bumblebees and honeybees played limited roles as pollinators. As documented by fossils from Europe, the Rhodoleia stem lineage dates back at least to the Paleocene. Bird pollination, however, is unlikely to have evolved before the Oligocene when sunbirds arrived in Europe, and pollination by Z. japonicus cannot be much older than 250,000 million years ago, when Z. japonicus diverged from its closest relative.     

华凤仙花部特征和传粉系统研究

研究了华凤仙（Impatiens chinensis L.）的花部特征和传粉系统,结果表明华凤仙单花期为2.3 d,雄性期是雌性期的6.8倍。花蜜量和花蜜可溶性糖含量分别为0.56 μL和28.2%。开花当天柱头即具有可授性,花粉活力在花朵刚开放时最高（95%）,至花朵凋谢之前仍保持较高的活力（55%）。花粉胚珠比（5 730.3±2 941.1）和套袋实验的结果表明华凤仙属于自交亲和但以异交为主的繁育系统,传粉过程需要传粉者。蜜蜂、熊蜂、蝶类和几种芦蜂是华凤仙的主要访花者,最有效的传粉者为三条熊蜂。考氏无垫蜂作为盗蜜者,可能是除正常访花者之外,对华凤仙的有性繁殖影响最大的生物因素。     

Deceptive pollination of Calanthe by skippers that commonly act as nectar thieves

Flowers have developed different strategies to attract pollinators through visual or olfactory signals. Most flowers offer pollinators a reward (e.g. nectar and pollen) for the pollination service. However, one‐third of Orchidaceae have been shown not to provide a reward. Calanthe are terrestrial orchids distributed throughout China, Nepal, Japan and tropical Asia. Despite its high diversity, the pollination biology of Calanthe remains largely unknown, even though it is an important aspect of plant conservation. In the study, through field surveying, there were three Hesperiidae butterflies pollinating two species of Calanthe and the pollination behavior differed between the two species of Calanthe, which might lead to different fruit setting rates. There was no nectar in the flowers of the two species, indicating deceptive pollination. Using a glass cylinder experiment, it was deduced that the two species of Calanthe were most likely to attract pollinators by generalized food deception. Interestingly, Hesperiidae butterflies were traditionally thought to be nectar thieves and generally do not transmit pollinia. However, our findings showed that, in this case, the thieves were deceived by the plants and pollinated them for free.     

Floral biology and pollination mechanisms of four Mexico-endemic Fuchsia species with contrasting reproductive systems

Aims The evolution of the outstanding variation of reproductive systems in angiosperms has been considered an important driver of lineage diversification. Closely related hermaphroditic and dioecious species with biotic pollination provide the opportunity to study and compare traits related to pollinator attraction and their consequences on reproductive components. A higher predictability of pollination syndromes is expected in dioecious species, which are dependent on pollinators, than in self-compatible hermaphroditic taxa. Dioecious species may suffer pollen limitation depending on the quality of floral rewards and the kind and abundance of pollinators, whereas no pollen limitation is expected in hermaphroditic species with autonomous self-pollination. Additionally, in the absence of pollen limitation, more or better seeds are expected in dioecious species, according to the sexual specialization hypothesis.Methods In natural populations of the hermaphroditic Fuchsia fulgens and Fuchsia arborescens and dioecious Fuchsia parviflora and Fuchsia obconica, all endemic to Mexico, we first described flower phenology, flower production and longevity and nectar volume and concentration. Then, we evaluated the correspondence between floral visitors and pollination syndromes. In hermaphrodite plants, we determined the level of herkogamy and the potential for autonomous self-pollination. Finally, we evaluated the effect of pollen limitation on fruit set and seed number and assessed seed germination for all species.Important findings In contrast to our prediction, dioecious species did not show a higher correspondence between pollination syndromes and floral visitors than did hermaphrodites; however, male flowers exhibited a higher correspondence than female flowers. No pollen limitation was detected in dioecious species, for which visitation rate did not differ between male and female flowers. The hermaphroditic F. fulgens showed pollen limitation for seed number, despite the presence of autonomous selfing. Fruit set from autonomous pollination was higher in F. arborescens, which showed a lower level of herkogamy compared with F. fulgens. Finally, dioecious species produced fewer but heavier seeds compared with hermaphrodite species. Although Fuchsia is classified as an outcrossing genus, both hermaphroditic species showed autonomous self-pollination. The heavier but lower number of seeds per fruit in dioecious species may be related to the more efficient resource allocation expected from sexual specialization. This could play an important role in the evolution of dioecy; however, a comparative phylogenetic approach is required to confirm this hypothesis.     

双翅目昆虫传粉研究进展

昆虫传粉不仅在自然生态系统中发挥着十分重要的作用,也和农业生态系统中产量密切相关。众所周知,膜翅目昆虫是最重要的传粉昆虫。双翅目昆虫分布广,物种多,数量大,也是一类十分重要的传粉昆虫,但其传粉作用未受到足够的重视。本文主要综述了双翅目传粉昆虫的主要种类、传粉效力、传粉特征、与植物的协同进化以及双翅目昆虫传粉的生态学意义。据记载双翅目昆虫中至少有71个科涉及虫媒种类,目前有资料显示访花昆虫类群中双翅目约有54 417种,按涉及的种数排序居于昆虫纲传粉昆虫目中第4位。尽管双翅目昆虫单次访问可携带花粉量相对较少(相比于膜翅目),但是较高访问速率及庞大的个体数量,保证了其作为有效传粉者的地位。传粉综合征能够有效揭示植物与传粉者的协同进化关系,尤其是对一些专化传粉现象(如五味子科-瘿蚊系统)和泛化传粉的深入研究,更加深了我们对协同进化的理解。就生态学意义而言,一方面双翅目传粉昆虫是膜翅目传粉昆虫的有益补充,另一方面在一些特殊环境中,双翅目昆虫具有不可替代的作用。当前传粉昆虫(包括双翅目)数量急剧下降,而且双翅目昆虫的传粉价值还利用较少。结合我国当前的研究现状提出了以下未来研究重点:1)加深双翅目传粉效力和适应意义的案例研究以明确双翅目昆虫在传粉体系中的地位;2)加强栖息地格局变化与昆虫多样性的研究以明确栖息地改变对昆虫的影响程度;3)梳理访花和传粉、专化传粉和泛化传粉等关系以更加明确双翅目昆虫在与植物协同进化中的作用;4)逐步深入探讨花粉浪费和花粉竞争以探究传粉策略和植物繁殖策略。这些努力将为双翅目传粉昆虫的知识普及、资源保护与利用研究等方面提供参考。