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1.
Quantitative and spatial data for orchid pollination are scarce and may be important tools for reintroduction and conservation; however, conclusions cannot be drawn on the basis of the typically infrequent and unpredictable pollination events. We carried out a novel, retrospective, spatial analysis of the pollination of the entire population of two miniature orchids, Erycina crista‐galli and Notylia barkeri, on coffee bushes in plantations at 900 m in Soconusco, south‐eastern Mexico. The numbers of mature flowering plants of both species in the experimental site were similar. Notylia barkeri produced nearly four times as many flowers, but a similar proportion of the total number of flowers produced was pollinated (1.23% and 1.48% for N. barkeri and E. crista‐galli, respectively). An estimated 29 919 977 (±4 983 995) seeds were produced by N. barkeri, nearly 12 times more than E. crista‐galli at 1 009 414 (±147 000). The pollinators of N. barkeri chose flower clusters at random and pollinated various flowers within a patch, whereas the pollinators of E. crista‐galli chose patches of flowers slightly more systematically, with less dependence on flower density, and appeared to dedicate less attention to each patch. For both species, pollinators slightly favoured larger clusters of flowers and left many individual and groups of flowers unvisited. To restore populations of these orchids in coffee plantations as a replacement habitat, N. barkeri should be planted in small, separate groups and E. crista‐galli in larger groups of individuals, dispersed regularly throughout the selected site to maximize the possibility that the flowers will be discovered by pollinators. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 448–459.  相似文献   

2.
The breeding system of the terrestrial orchid Eulophia alta was investigated in south Florida where it has previously been reported as an auto‐pollinated species. The effect of breeding system on seed viability and germinability and seedling development was also investigated. Incidences of spontaneous autogamy in E. alta were rare at the study site, resulting in only 7.1% of observed flowers forming capsules. In addition, hand pollination resulted in significantly greater capsule formation when flowers were subjected to induced autogamy (46.4%), artificial geitonogamy (64.3%) and xenogamy at both short (pollen source 10–100 m away; 42.9%) and long (pollen source > 10 km away; 67.9%) distances. Pollen source had little effect on seed viability and germinability or seedling growth rates. However, seed resulting from spontaneous autogamy developed more slowly than seed originating from the other treatments. These data indicate that spontaneous autogamy is rare in E. alta and that naturally forming capsules may be the result of unobserved pollination events. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 161 , 78–88.  相似文献   

3.
Pollinator‐mediated selection does not seem to have a direct influence on the evolution of a long corolla tube in a nectarless flower. We hypothesized that the long pistil length of the nectarless flower with a deep corolla tube provided an opportunity for male competition. Pedicularis siphonantha, a nectarless and partially self‐incompatible lousewort with substantial variation in corolla tube length, was used to test the hypothesis. We tested whether and how corolla tube length affected seed production per capsule and seed germination rate with different pollination treatments. Flowers were hand‐pollinated with pollen from one self donor and one outcross donor and mixed pollen grains consisting of equal amounts from the two donor types, respectively. Additionally, seeds from open‐pollinated flowers with different corolla tube lengths were collected separately for measurement of germination rate. Pollination treatment and corolla tube length significantly affected number of seeds per capsule. Moreover, a significant positive relationship between seeds per capsule and corolla tube length was found when mixed hand pollination was conducted. Seeds of self hand‐pollinated flowers had a lower germination rate than those from outcross‐pollinated flowers. Under open pollination, seeds from flowers with longer corolla tubes tended to have higher germination rate. In P. siphonantha, outcross pollen may have a higher probability of contributing to the next generation when transferred to flowers with longer corolla tubes. The pistil length, therefore, should be seen as a female choice mechanism, which provides an arena for male‐to‐male competition. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 526–532.  相似文献   

4.
One of the challenges facing orchid conservationists is to get a better understanding of seed parent fecundity. This can be especially laborious for orchids whose seed is difficult to germinate. Mature seeds ofCypripedium calceolusvar.pubescens(Willd.) Correll (Orchidaceae) have been reported to require 8 weeks pre-chilling at 4°C and a further month at 20°C to induce germination, but seeds prematurely harvested at 7–8 weeks post-pollination germinate asymbiotically without chilling in less than 1 month. Mature seeds ofEpipactis helleborine(L.) Crantz (Orchidaceae) have also presented a challenge but the identification of plants whose seeds are quick and easy to germinate has provided us with a tool to study patterns of production of this seed class. Preliminary field experiments suggest that timing of pollination in these two taxa is critical for the development of seed. When seeds from capsules ofC. calceolusvar.pubescensharvested 7 weeks after pollination were examined, the proportion of fully mature embryos increased with increasing anthesis-pollination interval over the first 10 days. Paired flowers from five genets xenogamously hand-pollinated at 2-day intervals from the second day after anthesis until the flowers wilted were significantly less likely to produce fruits as the flowers aged but the flower age at which this occurred varied between genets. The germinability of seeds from different pollen and seed parent combinations was tested on eight different media formulations and over a range of post-anthesis and post-pollination intervals. Different aged seeds germinated variably, the post-anthesis interval being the most reliable predictor of germination outcomes. Intercrossing of plants ofC. calceolusvar.pubescenssuggests that seed production and germinability are maternally mediated traits. WithE. helleborine, germinable seed can be produced both by self- and by cross-pollination of selected plants but we have observed an influence of flower position in the inflorescence on self-compatibility and on the production of the easy-to-germinate seed class. The timing of pollination in these two unrelated orchids has a considerable influence upon seed production and seed quality in plants of established fecundity. These findings suggest that flower age at pollination must be considered when interpreting similar studies in the Orchidaceae.  相似文献   

5.
Reproductive phenology, floral biology, degree of self‐incompatibility, and floral visitors of Erythrina falcata were studied in an Argentinean population. Flowering occurs during the dry season from late August to late October. Flower lifetime is 5–6 d. Phylogenetic studies indicate that E. falcata, together with E. fusca and E. crista‐galli, are included in a basal clade within Erythrina. Its phylogenetic position, floral morphology, and nectar characteristics suggest a hummingbird–passerine mixed pollination system. The flowers are nontubular, and the vexillum (the upper petal of the corolla) covers the other remaining floral parts until displaced by a visiting passerine (Icterus cayanensis) or a hummingbird (Amazilia chionogaster). Both birds act as pollen vectors. Bees were observed as occasional pollinators. Nectar production begins at anther dehiscence and coincides with maximum stigmatic receptivity. The base of the keel forms a secondary nectar reservoir. Controlled pollinations showed that this species is self‐incompatible, although a few fruits develop from selfing. Pollen:ovule ratio (43,200:7) is as expected for a xenogamous plant. Only 1 percent of the flowers set seeds under natural conditions. Possible explanations for the low reproductive success are discussed.  相似文献   

6.
Natural fruit set is constrained by pollen limitation and fruiting failure, and pollen limitation is expected to be especially severe in deceptive orchids. We performed hand cross‐pollinations in ten populations of a food‐deceptive orchid, Calypso bulbosa, under sparse and dense canopies in three non‐consecutive years. We explored the relationships between natural fruit set, pollen limitation and fruiting failure. Mean natural fruit set over the years was 60%, which is exceptionally high for a deceptive orchid. On average, hand cross‐pollination increased fruit set by 23%. Among open‐pollinated plants that did not set a fruit, 55.5% were estimated to be pollen limited and 44.5% to be limited by fruiting failure, i.e. inability to set a fruit after pollination. In species with high natural fruit set, hand cross‐pollination experiments may not always detect statistically significant pollen limitation. In our case, pollen limitation tended to become significant when the natural fruit set dropped below 60%. Canopy cover had a significant effect on fruiting failure, which was more severe under a dense canopy. Although our results demonstrate pollen limitation in many cases, they also highlight the fact that food deception can be a very effective pollination strategy. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013 , 171 , 744–750.  相似文献   

7.
Pollination by rodents, originally discovered in Cape Proteaceae, is known from a handful of plant lineages and may be more widespread than current data suggest. Here, we demonstrate the occurrence of this mode of pollination in Erica, the largest plant genus in the Cape flora of South Africa. The localized endemic Erica hanekomii appears to be adapted for pollination by rodents, on account of its low, mat‐forming habit with many dull‐coloured, pendulous flower heads, large volumes (up to c. 30 µL per inflorescence) of sucrose‐dominated nectar, hook‐shaped styles and late winter flowering phenology. Rodents trapped in the vicinity of E. hanekomii plants had many thousands of Erica tetrads in their droppings. Nocturnal laboratory observation showed that Acomys subspinosus (Cape spiny mouse) is adept at manipulating E. hanekomii inflorescences and lapping nectar without destroying gynoecia. During terrarium experiments, pollen was deposited mainly on the rostrum, but also on the chest area and forelegs of A. subspinosus. No birds or insects were seen to visit E. hanekomii in the field. Whereas natural fruit set was 73%, inflorescences from which rodents, but not insects, were excluded using mesh cages, had fruit set of just 3.3%. Exclusion of all visitors resulted in zero seed production. Broken anther rings (a sign of flower visitation in Erica) were observed in 90.1% of flowers in the field and 92% of flowers exposed to rodents in the laboratory, but in virtually none of the flowers from which rodents were selectively excluded. This first record of a non‐flying mammal pollination syndrome in Ericaceae raises interesting new questions about the origins of the rodent pollination system and the selective factors that lead to its evolution. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 166 , 163–170.  相似文献   

8.
Cross‐ and self‐fertilization in angiosperms are regulated by several factors, and a knowledge of the mechanism and time of spontaneous self‐pollination offers opportunities for a better understanding of the evolution of mating systems and floral traits. The floral biology of five species of Gentianaceae found in high‐altitude neotropical grassland is presented, with emphasis on the mechanisms that promote spontaneous self‐pollination. A presumed floral Batesian mimicry system is suggested between the rare and rewardless Zygostigma australe and Calydorea campestris, a species of Iridaceae with pollen‐flowers, pollinated by syrphids and bees. The floral morphology of the other four gentian species points to three different pollination syndromes: melittophily, phalaenophily and ornithophily. However, with the exception of the nocturnal Helia oblongifolia, flowers are nectarless and appear to exhibit non‐model deceptive mechanisms, providing similar floral cues to some sympatric rewarding species with the same syndrome. The similar mechanism of spontaneous self‐pollination in Calolisianthus pedunculatus, Calolisianthus pendulus and H. oblongifolia (Helieae) is based on the stigmatic movements towards the anthers. Selfing is promoted by movements of the style/stigma and of the corolla in Deianira nervosa and Z. australe (Chironieae), respectively. The movements of stamens, style and stigma during anthesis seem to be the most common method of spontaneous self‐pollination in angiosperms. It is suggested that the evolution of delayed spontaneous self‐pollination would be more expected in those taxa with dichogamous flowers associated with herkogamy. Such a characteristic is frequent in long‐lived flowers of certain groups of Asteridae, which comprise most documented cases of autonomous selfing. Thus, the presence of dichogamy associated with herkogamy (which supposedly evolved as a result of selection to promote both separation of male and female functions and the efficient transfer of cross pollen) may be the first step in the adaptive evolution of delayed selfing to provide reproductive assurance. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 160 , 357–368.  相似文献   

9.
Non‐rewarding orchids rely on various ruses to attract their pollinators. One of the most common is for them to resemble flowers sought by insects as food sources. This can range from generalized food deception to the mimicry of specific sympatric food plants. We investigated the basis of pollinator deception in the European food‐deceptive orchid Traunsteinera globosa, which has unusually compact flowerheads resembling those of sympatric rewarding species of Knautia and Scabiosa (Dipsacaceae), and Valeriana (Caprifoliaceae). Visual signals of T. globosa are similar in both fly and bee vision models to those of the sympatric food plants used in the choice experiments, but scent signals are divergent. Field experiments conducted in Austria and the Czech Republic showed that both naive and experienced (with respect to visitation of T. globosa) insect species approached the orchids at the same rate as food plants, but direct contact with orchid flowers was taxon specific. Flies were most easily duped into probing the orchid, and, in doing so, frequently received and deposited pollinaria, whereas most bees and butterflies avoided landing on orchid flowers. We conclude that T. globosa is a mimic of a guild of fly‐pollinated plants, but the ecological dependence of the orchid on its models remains to be fully tested. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2016, 180 , 269–294.  相似文献   

10.
Pollination via sexual deception is hypothesised to be associated with more frequent outcrossing and greater pollen dispersal distances than strategies involving food‐foraging behaviour. In this study, we investigated the behaviour and movement distances of Lissopimpla excelsa (Hymenoptera: Ichneumonidae), and their implications for the pollination of the sexually deceptive Cryptostylis ovata (Orchidaceae). Pollinator observations revealed that while L. excelsa will alight on multiple flowers within a single visit to a patch of orchids, the frequency of attempted copulation decreases with successive visits, suggesting that pollinator learning may inhibit within‐patch pollen transfer. Mark‐recapture demonstrated that 25% of wasps revisited inflorescences within a day and 50% revisited within a week. Despite the apparent site fidelity of some individuals, L. excelsa often move over large distances (maximum = 625 m), and are capable of dispersing pollen between patches. To resolve the consequences of pollination by sexual deception of ichneumonids, we compared our results with those from studies of other sexually deceptive systems. While pollination rates were comparable with other sexually deceptive orchids, L. excelsa showed high rates of column contact and moved over large distances relative to other sexually deceived pollinators. Among sexually deceptive orchids in general, the frequency of column contact was not correlated either with the frequency of pseudocopulation or with pollination rate. These results suggest that the consequences of pollination by sexual deception may vary extensively between plant taxa due to variation in floral traits, and behavioural differences between pollinator groups.  相似文献   

11.
Non‐rewarding plants use a variety of ruses to attract their pollinators. One of the least understood of these is generalized food deception, in which flowers exploit non‐specific food‐seeking responses in their pollinators. Available evidence suggests that colour signals, scent and phenology may all play key roles in this form of deception. Here we investigate the pollination systems of five Eulophia spp. (Orchidaceae) lacking floral rewards. These species are pollinated by bees, notably Xylocopa (Anthophorinae, Apidae) or Megachile (Megachilidae) for the large‐flowered species and anthophorid (Anthophorinae, Apidae) or halictid (Halictidae) bees for the small‐flowered species. Spectra of the lateral petals and ultraviolet‐absorbing patches on the labella are strongly contrasting in a bee visual system, which may falsely signal the presence of pollen to bees. All five species possess pollinarium‐bending mechanisms that are likely to limit pollinator‐mediated self‐pollination. Flowering times extend over 3–4 months and the onset of flowering was not associated with the emergence of pollinators, some of which fly year round. Despite sharing pollinators with other plants and lacking rewards that would encourage fidelity, the Eulophia spp. exhibited relatively high levels of pollen transfer efficiency compared with other rewarding and deceptive orchids. We conclude that the study species employ generalized food deception and exploit food‐seeking bees. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013 , 171 , 713–729.  相似文献   

12.
The pollination biology of the nectarless orchid Pogonia minor was investigated in central Japan. The investigation revealed that the solitary flowers failed to attract pollinators, while high rates of fruit set were observed in the natural population. Comparable levels of fruit set were obtained in bagged, artificial self‐pollinated and artificial cross‐pollinated plants, indicating that the species is not pollinator‐limited for fruit set under natural conditions. Autonomous self‐pollination in P. minor resulted from a reduced rostellum, which allowed contact between the pollinia and the stigma. Self‐pollination is thought to be an adaptive response that provides reproductive assurance under conditions of pollinator limitation. Since pollen limitation is generally known to be frequent among deceptive orchids, strong pollen limitation is probably a driving force in the autonomous self‐pollination mechanism in the nectarless orchid P. minor.  相似文献   

13.
Ipomoea habeliana is an endemic, night‐flowering member of the Galápagos flora. Pollination experiments, flower‐visitor observations, nectar sampling, pollen transfer, and pollen to ovule ratio and pollen size studies were included in this project. The large, white flowers of this species set fruit via open pollination (55%), autonomous autogamy (51%), facilitated autogamy (91%), cross‐pollination (80%), diurnal open pollination (60%) and nocturnal open pollination (60%). Fruit set is pollen‐limited. Ants, beetles, crickets and hawk moths regularly visit the flowers. Ants are the most frequent visitors, but hawk moths are the only effective pollinators. Nectar is available throughout the night, but is most abundant early in the evening when hawk moth visits are most frequent. Experiments with fluorescent dust demonstrate intra‐ and inter‐plant pollen movement by hawk moths. Although this species is adapted for hawk moth pollination, it readily sets fruit via autonomous autogamy when no visits are made. Thus, it is concluded that it is facultatively xenogamous. Additional support for this conclusion is provided by the pollen to ovule ratio of 1407 and by the fact that the plants grow in a region that has few or no faithful pollinators. Conservation efforts for I. habeliana should include hand pollinations, which could significantly increase seed set. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 160 , 11–20.  相似文献   

14.
15.
Calanthe striata has nectarless flowers that are self‐compatible, but pollinator dependent. Field observations showed that the flowers were pollinated exclusively by the carpenter bee Xylocopa appendiculata circumvolans, although the bees occasionally wasted pollen by delivering to the stigmatic surface pollinaria that retained their anther caps. Fruit set ratios at the population level varied spatiotemporally, but were generally low (8.3–17.3%). Calanthe striata blooms in spring when post‐overwintering carpenter bees have not yet started foraging for brood production. It can therefore exploit an abundance of opportunistic/naïve foragers. This timing may also increase the possibility of pollinator visits, because no rewarding co‐flowering plants are available in the orchid habitats. A literature review of Orchidaceae pollinated by carpenter bees revealed that at least 14 species of Orchidoideae and Epidendroideae have evolved flowers specialized for carpenter bee pollination. They typically have shallow pink/magenta flowers with a foothold for pollinators; pollinaria are attached to the head, ventral thorax or base of the middle legs of carpenter bees when they insert their heads and/or proboscises into flowers; pollination success is generally low, a probable consequence of the deceptive pollination systems. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013 , 171 , 730–743.  相似文献   

16.
  • The evolution of monomorphisms from heterostylous ancestors has been related to the presence of homostyly and the loss of self‐incompatibility, allowing the occurrence of selfing, which could be advantageous under pollinator limitation. However, flowers of some monomorphic species show herkogamy, attraction and rewarding traits that presumably favour cross‐pollination and/or a mixed mating system. This study evaluated the contributions of pollinators, breeding system and floral traits to the reproduction of Turnera velutina, a herkogamous monomorphic species.
  • Floral visitors and frequency of visits were recorded, controlled hand cross‐pollinations were conducted under greenhouse and natural conditions, and individual variation in floral traits was characterised to determine their contribution to seed production.
  • Apis mellifera was the most frequent floral visitor. Flowers presented approach herkogamy, high variation in nectar features, and a positive correlation of floral length with nectar volume and sugar concentration. Seed production did not differ between manual self‐ and cross‐pollinations, controls or open cross‐pollinations, but autonomous self‐pollination produced, on average, 82.74% fewer seeds than the other forms, irrespective of the level of herkogamy.
  • Differences in seed production among autonomous self‐pollination and other treatments showed that T. velutina flowers depend on insect pollination for reproduction, and that approach herkogamy drastically reduced seed production in the absence of pollen vectors. The lack of differences in seed production from manual cross‐ and self‐pollinations suggests the possible presence of a mixed mating system in the studied population. Overall, this species was possibly derived from a distylous ancestor but appears fully capable of outcrossing despite being monomorphic.
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17.
18.
  • Caladenia is a diverse Australian genus that is exceptional among orchids in having both species pollinated by food‐seeking and sexually deceived insects. Here, we investigated the pollination of Caladenia nobilis, a species predicted to be food‐deceptive due to its large, cream‐coloured and apparently nectarless flowers.
  • Pollinator observations were made using experimental clumps of flowers. Measurements of floral colour were undertaken with a spectrometer, nectar was tested using GC‐MS, and reproductive success was quantified for 2 years.
  • While C. nobilis attracted nine species of insect, only males of the thynnine wasp Rhagigaster discrepans exhibited the correct size and behaviour to remove and deposit pollen. Male R. discrepans attempted to feed from the surface of the labellum, often crawling to multiple flowers, but showed no evidence of sexual attraction. Most flowers produced little or no nectar, although some may provide enough sucrose to act as a meagre reward to pollinators. Floral colouration was similar to a related Caladenia species pollinated by sexual deception, although the sexually deceptive species had a dull‐red labellum. Reproductive success was generally low and highly variable between sites and years.
  • In addition to most visitors being of inappropriate size for pollinia removal, the lack of response to the orchid by several co‐occurring species of thynnine wasp suggests filtering of potential pollinators at the attraction phase. Our discovery of a pollination strategy that may be intermediate between food deception and food reward raises the question, how many putatively rewardless orchids actually produce meagre amounts of nectar?
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19.
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.  相似文献   

20.
The majority of flowering plants rely on animals as pollen vectors. Thus, plant mating systems and pollen dispersal are strongly influenced by pollinator behaviour. In Australian sexually deceptive orchids pollinated by male thynnine wasps, outcrossing and extensive pollen flow is predicted due to floral deception, which minimizes multiple flower visitations within patches, and the movement of pollinators under mate‐search rather than foraging behaviours. This hypothesis was tested using microsatellite markers to reconstruct and infer paternity in two clonal, self‐compatible orchids. Offspring from naturally pollinated Chiloglottis valida and C. aff. jeanesii were acquired through symbiotic culture of seeds collected over three seasons. In both species, outcrossing was extensive (tm = 0.924–1.00) despite clone sizes up to 11 m wide. The median pollen flow distance based on paternity for both taxa combined was 14.5 m (n = 18, range 0–69 m), being larger than typically found by paternity analyses in other herbaceous plants. Unexpectedly for orchids, some capsules were sired by more than one father, with an average of 1.35 pollen donors per fruit. This is the first genetic confirmation of polyandry in orchid capsules. Further, we report a possible link between multiple paternity and increased seed fitness. Together, these results demonstrate that deceptive pollination by mate‐searching wasps enhances offspring fitness by promoting both outcrossing and within‐fruit paternal diversity.  相似文献   

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