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Scaccabarozzi D, Guzzetti L, Pioltelli E, Brundrett M, Aromatisi A, Polverino G, Vallejo-Marin M, Cozzolino S, Ren ZX. Evidence of introduced honeybees (Apis mellifera) as pollen wasters in orchid pollination. Sci Rep 2024; 14:14076. [PMID: 38890342 PMCID: PMC11189403 DOI: 10.1038/s41598-024-64218-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Accepted: 06/06/2024] [Indexed: 06/20/2024] Open
Abstract
Biological invasions threaten global biodiversity, altering landscapes, ecosystems, and mutualistic relationships like pollination. Orchids are one of the most threatened plant families, yet the impact of invasive bees on their reproduction remains poorly understood. We conduct a global literature survey on the incidence of invasive honeybees (Apis mellifera) on orchid pollination, followed by a study case on Australian orchids. Our literature survey shows that Apis mellifera is the primary alien bee visiting orchids worldwide. However, in most cases, introduced honeybees do not deposit orchid pollen. We also test the extent to which introduced honeybees affect orchid pollination using Diuris brumalis and D. magnifica. Diuris brumalis shows higher fruit set and pollination in habitats with both native and invasive bees compared to habitats with only introduced bees. Male and female reproductive success in D. magnifica increases with native bee abundance, while conversely pollinator efficiency decreases with honeybee abundance and rises with habitat size. Our results suggest that introduced honeybees are likely involved in pollen removal but do not effectively deposit orchid pollen, acting as pollen wasters. However, Apis mellifera may still contribute to pollination of Diuris where native bees no longer exist. Given the global occurrence of introduced honeybees, we warn that certain orchids may suffer from pollen depletion by these invaders, especially in altered habitats with compromised pollination communities.
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Affiliation(s)
- Daniela Scaccabarozzi
- Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18 D, 752 36, Uppsala, Sweden.
- School of Molecular and Life Sciences, Curtin University, Perth, Australia.
| | - Lorenzo Guzzetti
- ZooPlantLab, Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | - Emiliano Pioltelli
- ZooPlantLab, Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | - Mark Brundrett
- School of Biological Sciences, University of Western Australia, Crawley, Australia
| | | | - Giovanni Polverino
- Department of Ecological and Biological Sciences, University of Tuscia, Viterbo, Italy
| | - Mario Vallejo-Marin
- Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18 D, 752 36, Uppsala, Sweden
| | | | - Zong-Xin Ren
- Kunming Institute of Botany, Chinese Academy of Sciences (CAS), Kunming, China
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Phillips RD, Bohman B, Peakall R, Reiter N. Sexual attraction with pollination during feeding behaviour: implications for transitions between specialized strategies. ANNALS OF BOTANY 2024; 133:273-286. [PMID: 37963103 PMCID: PMC11005785 DOI: 10.1093/aob/mcad178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Accepted: 11/13/2023] [Indexed: 11/16/2023]
Abstract
BACKGROUND AND AIMS Understanding the origin of pollination by sexual deception has proven challenging, as sexually deceptive flowers are often highly modified, making it hard to resolve how any intermediate forms between sexual deception and an ancestral strategy might have functioned. Here, we report the discovery in Caladenia (Orchidaceae) of sexual attraction with pollination during feeding behaviour, which may offer important clues for understanding shifts in pollination strategy. METHODS For Caladenia robinsonii, we observed the behaviour of its male wasp pollinator, Phymatothynnus aff. nitidus (Thynnidae), determined the site of release of the sexual attractant, and experimentally evaluated if the position of the attractant influences rates of attempted copulation and feeding behaviour. We applied GC-MS to test for surface sugar on the labellum. To establish if this pollination strategy is widespread in Caladenia, we conducted similar observations and experiments for four other Caladenia species. KEY RESULTS In C. robinsonii, long-range sexual attraction of the pollinator is via semiochemicals emitted from the glandular sepal tips. Of the wasps landing on the flower, 57 % attempted copulation with the sepal tips, while 27 % attempted to feed from the base of the labellum, the behaviour associated with pollen transfer. A similar proportion of wasps exhibited feeding behaviour when the site of odour release was manipulated. A comparable pollination strategy occurs in another phylogenetically distinct clade of Caladenia. CONCLUSIONS We document a previously overlooked type of sexual deception for orchids involving long-distance sexual attraction, but with pollination occurring during feeding behaviour at the labellum. We show this type of sexual deception operates in other Caladenia species and predict that it is widespread across the genus. Our findings may offer clues about how an intermediate transitional strategy from a food-rewarding or food-deceptive ancestor operated during the evolution of sexual deception.
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Affiliation(s)
- Ryan D Phillips
- Department of Environment and Genetics and the Research Centre for Future Landscapes, La Trobe University, Melbourne, Victoria 3086, Australia
- Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, ACT 2600, Australia
- Royal Botanic Gardens Victoria, Science Division, Corner of Ballarto Road and Botanic Drive, Cranbourne, VIC 3977, Australia
- Kings Park and Botanic Garden, The Botanic Garden and Parks Authority, West Perth, WA 6005, Australia
| | - Björn Bohman
- Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, ACT 2600, Australia
- Department of Plant Protection Biology, the Swedish University of Agricultural Sciences, Lomma 23422, Sweden
- School of Molecular Sciences, The University of Western Australia Crawley, WA 6009Australia
| | - Rod Peakall
- Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, ACT 2600, Australia
| | - Noushka Reiter
- Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, ACT 2600, Australia
- Royal Botanic Gardens Victoria, Science Division, Corner of Ballarto Road and Botanic Drive, Cranbourne, VIC 3977, Australia
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3
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Capó M, Borràs J, Perelló-Suau S, Rita J, Cursach J. Phenotype-fitness relationships and pollen-transfer efficiency of five orchid species with different pollination strategies. AMERICAN JOURNAL OF BOTANY 2023:e16198. [PMID: 37342959 DOI: 10.1002/ajb2.16198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 04/16/2023] [Accepted: 04/17/2023] [Indexed: 06/23/2023]
Abstract
PREMISE Deceptive pollination, a fascinating mechanism that independently originated in several plant families for benefiting from pollinators without providing any reward, is particularly widespread among orchids. Pollination efficiency is crucial in orchids due to the aggregated pollen in a pollinarium, which facilitates pollen transfer and promotes cross-pollination as pollinators leave after being deceived. METHODS In this study, we compiled data on reproductive ecology from five orchid species with different pollination strategies: three deceptive-strategy species (shelter imitation, food deception, sexual deception), one nectar-rewarding species, and one shelter-imitation but spontaneously selfing species. We aimed to compare the reproductive success (female fitness: fruit set; male fitness: pollinarium removal) and pollination efficiency of species representing these strategies. We also investigated pollen limitation and inbreeding depression among the pollination strategies. RESULTS Male and female fitness were strongly correlated in all species but the spontaneously selfing species, which had high fruit set and low pollinarium removal. As expected, pollination efficiency was highest for the rewarding species and the sexually deceptive species. Rewarding species had no pollen limitation but did have high cumulative inbreeding depression; deceptive species had high pollen limitation and moderate inbreeding depression; and spontaneously selfing species did not have pollen limitation or inbreeding depression. CONCLUSIONS Pollinator response to deception is critical to maintain reproductive success and avoid inbreeding in orchid species with non-rewarding pollination strategies. Our findings contribute to a better understanding of the trade-offs associated with different pollination strategies in orchids and highlight the importance of pollination efficiency in orchids due to the pollinarium.
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Affiliation(s)
- Miquel Capó
- Research Group on Plant Biology under Mediterranean Conditions, Department of Biology, University of Balearic Islands, Palma, Spain
- Departamento de Sistemas y Recursos Naturales, E.T.S.I. Montes, Universidad Politécnica de Madrid, Madrid, Spain
| | - Joshua Borràs
- Research Group on Plant Biology under Mediterranean Conditions, Department of Biology, University of Balearic Islands, Palma, Spain
| | - Sebastià Perelló-Suau
- Research Group on Plant Biology under Mediterranean Conditions, Department of Biology, University of Balearic Islands, Palma, Spain
| | - Juan Rita
- Research Group on Plant Biology under Mediterranean Conditions, Department of Biology, University of Balearic Islands, Palma, Spain
| | - Joana Cursach
- Research Group on Plant Biology under Mediterranean Conditions, Department of Biology, University of Balearic Islands, Palma, Spain
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Lanzino M, Palermo AM, Pellegrino G. Pollinaria Reconfiguration Mechanism of Widespread Euro-Mediterranean Orchids: The Effects of Increasing Air Temperature. PLANTS (BASEL, SWITZERLAND) 2022; 11:1327. [PMID: 35631751 PMCID: PMC9145125 DOI: 10.3390/plants11101327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 05/12/2022] [Accepted: 05/16/2022] [Indexed: 06/15/2023]
Abstract
Orchids are fascinating for many reasons: their reproductive strategies, their pollination systems and the various morphological adaptations they have evolved, including the presence of pollen grains agglomerated into two masses, called pollinia, which form a structure known as a pollinarium. After withdrawal from a flower, the pollinarium undergoes a bending movement such that the pollen masses become correctly orientated to strike the stigma. We evaluated the duration of pollinator visits to inflorescences and the effects of temperature on pollinaria reconfiguration in eight orchid species in order to analyze the effects of increasing air temperature on the changes in bending time, and thus on geitonogamy levels. The impact of temperature on insect behavior was not assessed because our priority was to understand the effects of temperature on the process of pollinaria reconfiguration. All the examined species showed natural reconfiguration times that were 1.7-3.0 times longer than the pollinator residency times. A higher temperature showed a reduction in bending time regardless of the species tested. However, the bending time was never shorter than the residence time of the insects on the flower. Our data showed that high temperatures had a limited effect on the pollinarium reconfiguration time, thus indicating that high temperatures had a limited effect on folding compared to the effect that it had on the viability of the pollen.
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Affiliation(s)
- Micaela Lanzino
- Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036 Rende, Italy
| | - Anna Maria Palermo
- Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036 Rende, Italy
| | - Giuseppe Pellegrino
- Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036 Rende, Italy
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5
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Knauer AC, Kokko H, Schiestl FP. Pollinator behaviour and resource limitation maintain honest floral signalling. Funct Ecol 2021. [DOI: 10.1111/1365-2435.13905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Anina C. Knauer
- Department of Systematic and Evolutionary Botany University of Zurich Zürich Switzerland
| | - Hanna Kokko
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zürich Switzerland
| | - Florian P. Schiestl
- Department of Systematic and Evolutionary Botany University of Zurich Zürich Switzerland
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Pollination in the Rainforest: Scarce Visitors and Low Effective Pollinators Limit the Fruiting Success of Tropical Orchids. INSECTS 2021; 12:insects12100856. [PMID: 34680625 PMCID: PMC8538420 DOI: 10.3390/insects12100856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 09/10/2021] [Accepted: 09/17/2021] [Indexed: 11/17/2022]
Abstract
A single plant might be visited by many flower visitors but not all might act as pollinators. Legitimate pollinators might also differ considerably in their efficiency, limiting pollination success. Unsuitable climatic conditions such as rain also affect pollinator activity. However, in the evergreen rainforest there is no prolonged dry season and flowering occurs usually under rain. Here, we explore the dependence on pollinators and the efficiency of flower visitors for the fruiting success of 10 Andean rainforest orchids. All species were self-compatible but strictly pollinator-dependent. Overall, we found low levels of fruit set in control flowers while experimental geitonogamous and cross-pollinations increased fruit set, revealing extensive pollination limitation in all populations. Seed viability dropped considerably after self and geitonogamous pollinations suggesting the possibility of early-acting inbreeding depression. Even though we monitored flower visitors on an extensive survey, few visitors were seen in these species and even fewer acted as legitimate pollinators. Thus, even though orchid pollination might be extremely diversified, these results show that few visitors are pollinating these species, explaining the low levels of fruit set recorded in the area studied.
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7
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Chen XH, Tan SL, Liang YL, Huang L, Xiao HW, Luo HL, Xiong DJ, Yang BY, Ren ZX. The pollination of Habenaria rhodocheila (Orchidaceae) in South China: When butterflies take sides. Ecol Evol 2021; 11:2849-2861. [PMID: 33767841 PMCID: PMC7981216 DOI: 10.1002/ece3.7242] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 01/06/2021] [Accepted: 01/13/2021] [Indexed: 11/10/2022] Open
Abstract
Habenaria is one of the largest terrestrial genera in the family Orchidaceae. Most field studies on Habenaria species with greenish-white and nocturnal scented flowers are pollinated by nocturnal hawkmoths and settling moths. However, H. rhodocheila presents reddish flowers lacking a detectable scent and fails to fit the moth pollination syndrome. We investigated the pollinators, breeding system, and functional traits of H. rhodocheila in South China and found that two diurnal swallowtail butterflies Papilio helenus and Papilio nephelus (Papilionidae) were the effective pollinators. When butterflies foraged for nectar in the spur, the pollinia became attached between the palpi. A triangular projected median rostellar lobe was found at the entrance (sinus) of the spur of H. rhodocheila. This lobe divided the spur opening into two entrances forcing butterflies to enter their proboscides through the left or right side. When the projection of median rostellar lobe was removed, the site of pollinium attachment changed to the eyes of the butterflies, leading to a higher rate of pollinium removal but lower rate of pollinium deposition. Our quartz glass cylinder choice experiment suggested that visual rather than olfactory cues provided the major stimuli for butterflies to locate these flowers. Hand pollination experiments suggested this species was self-compatible but pollinator-dependent. However, the proportion of seeds with large embryos produced in self-pollinated fruits was significantly lower than in cross-pollinated fruits, indicating a significant inbreeding depression. Unlike many other orchid species, fruit set was higher than rates of pollinium removal, indicating a high level of pollination efficiency in a species with friable pollinia. Shifts from moth to butterfly pollination in the genus Habenaria parallel other orchid lineages providing insights into the potential for pollinator-mediated floral trait selection.
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Affiliation(s)
- Xing-Hui Chen
- Jiangxi Key Laboratory of Plant Resources School of Life Sciences Nanchang University Nanchang China
| | - Shao-Lin Tan
- Jiangxi Key Laboratory of Plant Resources School of Life Sciences Nanchang University Nanchang China
| | - Yue-Long Liang
- Jiulianshan National Natural Reserve Administration Bureau Ganzhou China
| | - Lang Huang
- Jiangxi Key Laboratory of Plant Resources School of Life Sciences Nanchang University Nanchang China
| | - Han-Wen Xiao
- Jiangxi Key Laboratory of Plant Resources School of Life Sciences Nanchang University Nanchang China
| | - Huo-Lin Luo
- Jiangxi Key Laboratory of Plant Resources School of Life Sciences Nanchang University Nanchang China
| | - Dong-Jin Xiong
- Jiangxi Key Laboratory of Plant Resources School of Life Sciences Nanchang University Nanchang China
| | - Bo-Yun Yang
- Jiangxi Key Laboratory of Plant Resources School of Life Sciences Nanchang University Nanchang China
| | - Zong-Xin Ren
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia Kunming Institute of Botany Chinese Academy of Sciences Kunming China
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8
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Harder LD, Richards SA, Ågren J, Johnson SD. Mechanisms of Male-Male Interference during Dispersal of Orchid Pollen. Am Nat 2021; 197:250-265. [PMID: 33523780 DOI: 10.1086/712378] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractSiring success of flowering plants depends on the fates of male gametophytes, which compete for access to stigmas, stylar resources, and ovules. Although rarely considered, pollen may often compete during dispersal, affecting the processes required for export to stigmas: pollen pickup, transport, and deposition. We quantified dispersal interference by tracking bee-mediated dispersal of stained Anacamptis morio (Orchidaceae) pollen from individual donor flowers and inferred the affected dispersal mechanisms on the basis of the fit of a process-based model. During individual trials, all recipient flowers were either emasculated, precluding interference with donor pollen, or intact, adding potentially interfering pollen to the pollinator. The presence of competing pollinaria on bees reduced pickup of additional pollinaria, doubled the overall proportion of lost donor pollen, and reduced total pollen export by 27%. Interference specifically increased loss of donor pollen between successive flower visits and variation in deposition among trials, and it likely also reduced pollen contact with stigmas and pollen deposition when contact occurred. Thus, by altering pollen removal, transport, and deposition, male-male interference during pollen dispersal can significantly-and perhaps commonly-limit plant-siring success.
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Capó M, Borràs J, Perelló-Suau S, Rita J, Cursach J. Ecological factors affecting the fitness of the threatened orchid Anacamptis robusta (Orchidaceae): Habitat disturbance, interactions with a co-flowering rewarding orchid and hybridization events. PLANT BIOLOGY (STUTTGART, GERMANY) 2021; 23:121-129. [PMID: 32896978 DOI: 10.1111/plb.13179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 08/24/2020] [Indexed: 06/11/2023]
Abstract
The food-deceptive species Anacamptis robusta is threatened in the Balearic Islands, and its habitat has recently been transformed through human disturbance. This study investigated how human disturbance affects the reproductive output of A. robusta and how its fitness is affected by competition with rewarding relatives, fungal infections and hybridization processes. To evaluate the impact of habitat loss on plant fitness, data on reproductive measures were obtained in two well-conserved subpopulations and the unique disturbed subpopulation. Photo-trapping cameras were installed to determine the floral visitation rate. All flowering individuals in 2019 were georeferenced using differential GPS to examine the influence of geospatial patterns on the reproductive success of A. robusta. In addition, hand-pollination treatments were performed to evaluate the hybridization between A. coriophora and A. robusta and the origin of A. × albuferensis. The human-disturbed subpopulation of A. robusta had a lower fruit set success than the subpopulations in well-conserved areas. The presence of A. coriophora is negatively affecting the reproductive output of A. robusta. Moreover, A. robusta can only act as the pollen donor during hybridization. The complexity of the ecological system, which is enhanced by the strong pollinator dependence of the threatened species, must be considered when making conservation decisions. Although human disturbance directly affects plant population stability, other ecological issues must be considered, such as pollinator interaction, interspecific competition for pollinators, fungal infection and hybridization events.
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Affiliation(s)
- M Capó
- Laboratory of Botany, Research Group on Plant Biology under Mediterranean Conditions, Department of Biology, University of Balearic Islands, Palma, Spain
| | - J Borràs
- Laboratory of Botany, Research Group on Plant Biology under Mediterranean Conditions, Department of Biology, University of Balearic Islands, Palma, Spain
| | - S Perelló-Suau
- Laboratory of Botany, Research Group on Plant Biology under Mediterranean Conditions, Department of Biology, University of Balearic Islands, Palma, Spain
| | - J Rita
- Laboratory of Botany, Research Group on Plant Biology under Mediterranean Conditions, Department of Biology, University of Balearic Islands, Palma, Spain
| | - J Cursach
- Laboratory of Botany, Research Group on Plant Biology under Mediterranean Conditions, Department of Biology, University of Balearic Islands, Palma, Spain
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10
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Borràs J, Cursach J. Female and male fitness of a sexually deceptive orchid with a narrow distribution area: from phenotypic traits to spatial distribution patterns. PLANT BIOLOGY (STUTTGART, GERMANY) 2021; 23:130-139. [PMID: 32959484 DOI: 10.1111/plb.13184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 09/09/2020] [Indexed: 06/11/2023]
Abstract
The Orchidaceae family presents one of the most extravagant pollination mechanisms: deception. While many studies on reproductive success have been performed on food-deception orchids, less have been performed on sexually deceptive orchids. Here, we focused on Ophrys balearica P. Delforge, an endemic orchid of the Balearic Islands, to study its reproductive ecology, the spatio-temporal variation of its reproductive success and the individual (floral display and geospatial position) and population parameters (patch size, shape and density) that affect its reproductive success. We performed hand-pollination experiments, along with the recording of floral display parameters and GPS position of over 1,100 individuals from seven populations in two consecutive years. We applied, for the first time, GIS tools to analyse the effects of individual's position within the population on the reproductive success. Reproductive success was measured both in male (removed pollinia) and female (fruit set) fitness. The results confirm that this species is pollinator-dependent and mostly allogamous, but also self-compatible. This species showed high values for the cumulative inbreeding depression index and high pollen limitation. Male fitness was almost equal to female fitness between years and populations, and reproductive success exhibited huge spatio-temporal variation. Although we did not find strong correlations between floral display and reproductive success, patches with low-plant density and individuals in the external portion of the population showed significantly higher plant fitness. These findings must be considered in conservation actions for endangered orchid species, especially considering that most orchids are strongly dependent on pollinators for their species' fitness.
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Affiliation(s)
- J Borràs
- Laboratory of Botany, Research Group on Plant Biology under Mediterranean Conditions, Department of Biology, University of Balearic Islands, Palma, Spain
| | - J Cursach
- Laboratory of Botany, Research Group on Plant Biology under Mediterranean Conditions, Department of Biology, University of Balearic Islands, Palma, Spain
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Suetsugu K. Gynomonoecy in a mycoheterotrophic orchid Eulophia zollingeri with autonomous selfing hermaphroditic flowers and putatively outcrossing female flowers. PeerJ 2020; 8:e10272. [PMID: 33194432 PMCID: PMC7597633 DOI: 10.7717/peerj.10272] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 10/08/2020] [Indexed: 11/20/2022] Open
Abstract
Most orchid species exhibit an extreme case of hermaphroditism, owing to the fusion of male and female organs into a gynostemium. Exceptions to this rule have only been reported from the subtribes Catasetinae and Satyriinae. Here, I report an additional orchidaceous example whose flowers are not always hermaphroditic. In several Japanese populations of Eulophia zollingeri (Rchb.f.) J.J.Sm, a widespread Asian and Oceanian orchid, some flowers possess both the anther (i.e., anther cap and pollinaria) and stigma, whereas others possess only the stigma. Therefore, pollination experiments, an investigation of floral morphology and observations of floral visitors were conducted to understand the reproductive biology of E. zollingeri in Miyazaki Prefecture, Japan. It was confirmed that E. zollingeri studied here possesses a gynomonoecious reproductive system, a sexual system in which a single plant has both female flowers and hermaphroditic flowers. In addition, hermaphroditic flowers often possess an effective self-pollination system while female flowers could avoid autogamy but suffered from severe pollinator limitation, due to a lack of agamospermy and low insect-mediated pollination. The present study represents the first documented example of gynomonoecy within Orchidaceae. Gynomonoecy in E. zollingeri may be maintained by the tradeoff in reproductive traits between female flowers (with low fruit set but potential outcrossing benefits) and hermaphroditic flowers (with high fruit set but inbreeding depression in selfed offspring). This mixed mating is probably important in mycoheterotrophic E. zollingeri because it occurs in shaded forest understorey with a paucity of pollinators.
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Affiliation(s)
- Kenji Suetsugu
- Department of Biology, Graduate School of Science, Kobe University, Kobe, Japan
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12
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Pyke GH, Kalman JRM, Bordin DM, Blanes L, Doble PA. Patterns of floral nectar standing crops allow plants to manipulate their pollinators. Sci Rep 2020; 10:1660. [PMID: 32015366 PMCID: PMC6997191 DOI: 10.1038/s41598-020-58102-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 01/03/2020] [Indexed: 12/02/2022] Open
Abstract
‘Pollination syndromes’ involving floral nectar have eluded satisfactory evolutionary explanation. For example, floral nectars for vertebrate-pollinated plants average low sugar concentrations, while such animals prefer high concentrations, perplexing pollination biologists and arousing recent controversy. Such relationships should result from evolutionary games, with plants and pollinators adopting Evolutionarily Stable Strategies, and nectar manipulating rather than attracting pollinators. Plant potential to manipulate pollinators depends on relationships between neighbouring flowers within plants, for all nectar attributes, but this has not been investigated. We measured nectar volume, concentration and sugar composition for open flowers on naturally-growing Blandfordia grandiflora plants, presenting classic bird-pollinated plant syndrome. To evaluate potential pollinator manipulation through nectar, we analysed relationships between neighbouring flowers for nectar volume, concentration, proportion sucrose, log(fructose/glucose), and sugar weight. To evaluate potential attraction of repeat-visits to flowers or plants through nectar, we compared attributes between successive days. Nearby flowers were positively correlated for all attributes, except log(fructose/glucose) as fructose≈glucose. Most relationships between nectar attributes for flowers and plants on successive days were non-significant. Nectar-feeding pollinators should therefore decide whether to visit another flower on a plant, based on all attributes of nectar just-obtained, enabling plants to manipulate pollinators through adjusting nectar. Plants are unlikely to attract repeat pollinator-visits through nectar production. Floral nectar evolution is conceptually straightforward but empirically challenging. A mutant plant deviating from the population in attributes of nectar-production per flower would manipulate, rather than attract, nectar-feeding pollinators, altering pollen transfer, hence reproduction. However, links between floral nectar and plant fitness present empirical difficulties.
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Affiliation(s)
- Graham H Pyke
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, CN, 650201, Kunming, PR China. .,Department of Biological Sciences, Macquarie University, Ryde, NSW, 2109, Australia.
| | - John R M Kalman
- School of Mathematical & Physical Sciences, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - Dayanne M Bordin
- School of Mathematical & Physical Sciences, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - Lucas Blanes
- School of Mathematical & Physical Sciences, University of Technology Sydney, Ultimo, NSW, 2007, Australia.,Laboratory for Applied Science and Technology in Health, Carlos Chagas Institute, Oswaldo Cruz Foundation (Fiocruz), Curitiba, Brazil
| | - Philip A Doble
- School of Mathematical & Physical Sciences, University of Technology Sydney, Ultimo, NSW, 2007, Australia
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Bartoš M, Janeček Š, Janečková P, Padyšáková E, Tropek R, Götzenberger L, Klomberg Y, Jersáková J. Self-compatibility and autonomous selfing of plants in meadow communities. PLANT BIOLOGY (STUTTGART, GERMANY) 2020; 22:120-128. [PMID: 31549455 DOI: 10.1111/plb.13049] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 08/30/2019] [Indexed: 06/10/2023]
Abstract
One of the most fundamental, although controversial, questions related to the evolution of plant mating systems is the distribution of outcrossing rates. Self-compatibility, and especially autonomous self-pollination, can become particularly beneficial in anthropogenically degraded habitats with impoverished pollinator assemblages and increased pollen limitation. In a hand-pollination experiment with 46 meadow plants from the Železné hory Mts., Czech Republic, we evaluated the species' ability to adopt different mating systems. For a subset of the species, we also tested seed germination for inbreeding depression. Subsequently, we analysed relationships between the species' mating systems and 12 floral and life-history traits. We found a relatively discrete distribution of the studied species into four groups. Fully and partially self-incompatible species formed the largest group, followed by self-compatible non-selfers and mixed mating species. The germination experiment showed an absence of inbreeding depression in 19 out of 22 examined species. Nectar sugar per flower, nectar sugar per shoot and dichogamy were significant associated with the mating system. Spontaneous selfing ability and self-incompatibility in species of the meadow communities had a discrete distribution, conforming to the general distribution of mating and breeding systems in angiosperms. The low frequency of spontaneous selfers and the lack of inbreeding depression at germination suggest the existence of a selection against selfing at the later ontogenetic stages. Some floral traits, such as the level of dichogamy and amount of nectar reward, may strongly impact the balance between selfing and outcrossing rates in the self-compatible species and thus shape the evolution of mating systems.
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Affiliation(s)
- M Bartoš
- Institute of Botany, The Czech Academy of Sciences, Třeboň, Czech Republic
| | - Š Janeček
- Department of Ecology, Faculty of Science, Charles University, Praha, Czech Republic
| | - P Janečková
- Department of Ecology, Faculty of Science, Charles University, Praha, Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - E Padyšáková
- Department of Ecology, Faculty of Science, Charles University, Praha, Czech Republic
- Biology Centre, Institute of Entomology, The Czech Academy of Sciences, České Budějovice, Czech Republic
| | - R Tropek
- Department of Ecology, Faculty of Science, Charles University, Praha, Czech Republic
- Biology Centre, Institute of Entomology, The Czech Academy of Sciences, České Budějovice, Czech Republic
| | - L Götzenberger
- Institute of Botany, The Czech Academy of Sciences, Třeboň, Czech Republic
| | - Y Klomberg
- Department of Ecology, Faculty of Science, Charles University, Praha, Czech Republic
| | - J Jersáková
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
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Parachnowitsch AL, Manson JS, Sletvold N. Evolutionary ecology of nectar. ANNALS OF BOTANY 2019; 123:247-261. [PMID: 30032269 PMCID: PMC6344224 DOI: 10.1093/aob/mcy132] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Accepted: 06/16/2018] [Indexed: 05/24/2023]
Abstract
Background Floral nectar is an important determinant of plant-pollinator interactions and an integral component of pollination syndromes, suggesting it is under pollinator-mediated selection. However, compared to floral display traits, we know little about the evolutionary ecology of nectar. Combining a literature review with a meta-analysis approach, we summarize the evidence for heritable variation in nectar traits and link this variation to pollinator response and plant fitness. We further review associations between nectar traits and floral signals and discuss them in the context of honest signalling and targets of selection. Scope Although nectar is strongly influenced by environmental factors, heritable variation in nectar production rate has been documented in several populations (mean h2 = 0.31). Almost nothing is known about heritability of other nectar traits, such as sugar and amino acid concentrations. Only a handful of studies have quantified selection on nectar traits, and few find statistically significant selection. Pollinator responses to nectar traits indicate they may drive selection, but studies tying pollinator preferences to plant fitness are lacking. So far, only one study conclusively identified pollinators as selective agents on a nectar trait, and the role of microbes, herbivores, nectar robbers and abiotic factors in nectar evolution is largely hypothetical. Finally, there is a trend for positive correlations among floral cues and nectar traits, indicating honest signalling of rewards. Conclusions Important progress can be made by studies that quantify current selection on nectar in natural populations, as well as experimental approaches that identify the target traits and selective agents involved. Signal-reward associations suggest that correlational selection may shape evolution of nectar traits, and studies exploring these more complex forms of natural selection are needed. Many questions about nectar evolution remain unanswered, making this a field ripe for future research.
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Affiliation(s)
- Amy L Parachnowitsch
- Plant Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
- Department of Biology, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - Jessamyn S Manson
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Nina Sletvold
- Plant Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
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Minnaar C, Anderson B, de Jager ML, Karron JD. Plant-pollinator interactions along the pathway to paternity. ANNALS OF BOTANY 2019; 123:225-245. [PMID: 30535041 PMCID: PMC6344347 DOI: 10.1093/aob/mcy167] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 11/23/2018] [Indexed: 05/09/2023]
Abstract
Background The male fitness pathway, from pollen production to ovule fertilization, is thought to strongly influence reproductive trait evolution in animal-pollinated plants. This pathway is characterized by multiple avenues of pollen loss which may lead to reductions in male fitness. However, empirical data on the mechanistic processes leading to pollen loss during transport are limited, and we therefore lack a comprehensive understanding of how male fitness is influenced by each step in the pollination process. Scope This review assesses the history of studying male function in plants and identifies critical gaps in our understanding of the ecology and evolution of pollen transport. We explore male reproductive function along the steps of the pathway to paternity and discuss evolutionary options to overcome barriers to siring success. In particular, we present a newly emerging idea that bodies of pollinators function as a dynamic arena facilitating intense male-male competition, where pollen of rival males is constantly covered or displaced by competitors. This perspective extends the pollen-competitive arena beyond the confines of the stigma and style, and highlights the opportunity for important new breakthroughs in the study of male reproductive strategies and floral evolution.
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Affiliation(s)
- Corneile Minnaar
- Department of Botany and Zoology, Stellenbosch University, Matieland, South Africa
| | - Bruce Anderson
- Department of Botany and Zoology, Stellenbosch University, Matieland, South Africa
| | - Marinus L de Jager
- Department of Botany and Zoology, Stellenbosch University, Matieland, South Africa
| | - Jeffrey D Karron
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
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Tong ZY, Wang XP, Wu LY, Huang SQ. Nectar supplementation changes pollinator behaviour and pollination mode in Pedicularis dichotoma: implications for evolutionary transitions. ANNALS OF BOTANY 2019; 123:373-380. [PMID: 29878060 PMCID: PMC6344217 DOI: 10.1093/aob/mcy102] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 05/17/2018] [Indexed: 05/26/2023]
Abstract
BACKGROUNDS AND AIMS Gain or loss of floral nectar, an innovation in floral traits, has occurred in diverse lineages of flowering plants, but the causes of reverse transitions (gain of nectar) remain unclear. Phylogenetic studies show multiple gains and losses of floral nectar in the species-rich genus Pedicularis. Here we explore how experimental addition of nectar to a supposedly nectarless species, P. dichotoma, influences pollinator foraging behaviour. METHODS The liquid (nectar) at the base of the corolla tube in P. dichotoma was investigated during anthesis. Sugar components were measured by high-performance liquid chromatography. To understand evolutionary transitions of nectar, artificial nectar was added to corolla tubes and the reactions of bumble-bee pollinators to extra nectar were examined. KEY RESULTS A quarter of unmanipulated P. dichotoma plants contained measurable nectar, with 0.01-0.49 μL per flower and sugar concentrations ranging from 4 to 39 %. The liquid surrounding the ovaries in the corolla tubes was sucrose-dominant nectar, as in two sympatric nectariferous Pedicularis species. Bumble-bees collected only pollen from control (unmanipulated) flowers of P. dichotoma, adopting a sternotribic pollination mode, but switched to foraging for nectar in manipulated (nectar-supplemented) flowers, adopting a nototribic pollination mode as in nectariferous species. This altered foraging behaviour did not place pollen on the ventral side of the bees, and sternotribic pollination also decreased. CONCLUSION Our study is the first to quantify variation in nectar production in a supposedly 'nectarless' Pedicularis species. Flower manipulations by adding nectar suggested that gain (or loss) of nectar would quickly result in an adaptive behavioural shift in the pollinator, producing a new location for pollen deposition and stigma contact without a shift to other pollinators. Frequent gains of nectar in Pedicularis species would be beneficial by enhancing pollinator attraction in unpredictable pollination environments.
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Affiliation(s)
- Ze-Yu Tong
- Institute of Evolution and Ecology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Xiang-Ping Wang
- South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Ling-Yun Wu
- Institute of Evolution and Ecology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Shuang-Quan Huang
- Institute of Evolution and Ecology, School of Life Sciences, Central China Normal University, Wuhan, China
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Cardoso-Gustavson P, Saka MN, Pessoa EM, Palma-Silva C, Pinheiro F. Unidirectional transitions in nectar gain and loss suggest food deception is a stable evolutionary strategy in Epidendrum (Orchidaceae): insights from anatomical and molecular evidence. BMC PLANT BIOLOGY 2018; 18:179. [PMID: 30180799 PMCID: PMC6122447 DOI: 10.1186/s12870-018-1398-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 08/27/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Nectar gain and loss are important flower transitions observed in angiosperms, and are particularly common in orchids. To understand such transitions, the availability of detailed anatomical data and species-level phylogenies are crucial. We investigated the evolution of food deception in Epidendrum, one of the largest orchid genera, using genus phylogeny to map transitions between nectar gain and loss among different clades. Associations between anatomical and histochemical changes and nectar gain and loss were examined using fresh material available from 27 species. The evolution of nectar presence/absence in Epidendrum species was investigated in a phylogenetic framework of 47 species, using one nuclear and five plastid DNA regions available from GenBank and sequenced in this study. RESULTS The presence or absence of nectar was strongly associated with changes in the inner epidermal tissues of nectaries. Nectar-secreting species have unornamented epidermal tissue, in contrast to the unicellular trichomes found on the epidermis of food deceptive species. Bayesian tests confirmed that transitions occurred preferentially from nectar presence to nectar absence across the Epidendrum phylogeny. In addition, independent nectar loss events were found across the phylogeny, suggesting a lack of constraint for these transitions. CONCLUSIONS Ornamented nectaries may play an important role in the deceptive pollination strategy by secreting volatile organic compounds and providing tactile stimuli to pollinators. The recurrent and apparently irreversible pattern of nectar loss in Epidendrum suggests that food deception may constitute an alternative evolutionarily stable strategy, as observed in other orchid groups.
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Affiliation(s)
| | - Mariana Naomi Saka
- Departamento de Botânica, Instituto de Biociências, Universidade Estadual Paulista, Rio Claro, SP 13506-900 Brazil
| | - Edlley Max Pessoa
- Centro de Ciências Biológicas, Departamento de Botânica, Universidade Federal de Pernambuco, Recife, PE 50670-420 Brazil
| | - Clarisse Palma-Silva
- Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP 13083-862 Brazil
| | - Fabio Pinheiro
- Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP 13083-862 Brazil
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Aguiar JMRBV, Roselino AC, Sazima M, Giurfa M. Can honey bees discriminate between floral-fragrance isomers? J Exp Biol 2018; 221:jeb.180844. [DOI: 10.1242/jeb.180844] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 05/18/2018] [Indexed: 11/20/2022]
Abstract
Many flowering plants present variable complex fragrances, which usually include different isomers of the same molecule. As fragrance is an essential cue for flower recognition by pollinators, we ask if honey bees discriminate between floral-fragrance isomers in an appetitive context. We used the olfactory conditioning of the proboscis extension response (PER), which allows training a restrained bee to an odor paired with sucrose solution. Bees were trained under an absolute (a single odorant rewarded) or a differential conditioning regime (a rewarded vs. a non-rewarded odorant) using four different pairs of isomers. One hour after training, discrimination and generalization between pairs of isomers were tested. Bees trained under absolute conditioning exhibited high generalization between isomers and discriminated only one out of four isomer pairs; after differential conditioning, they learned to differentiate between two out of four pairs of isomers but in all cases generalization responses to the non-rewarding isomer remained high. Adding an aversive taste to the non-rewarded isomer facilitated discrimination of isomers that otherwise seemed non-discriminable, but generalization remained high. Although honey bees discriminated isomers under certain conditions, they achieved the task with difficulty and tended to generalize between them, thus showing that these molecules were perceptually similar to them. We conclude that the presence of isomers within floral fragrances might not necessarily contribute to a dramatic extent to floral odor diversity.
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Affiliation(s)
- João Marcelo Robazzi Bignelli Valente Aguiar
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse; CNRS, UPS, France
- Programa de Pós-Graduação em Ecologia, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil
| | - Ana Carolina Roselino
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - Marlies Sazima
- Programa de Pós-Graduação em Ecologia, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil
| | - Martin Giurfa
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Université de Toulouse; CNRS, UPS, France
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When it pays to cheat: Examining how generalized food deception increases male and female fitness in a terrestrial orchid. PLoS One 2017; 12:e0171286. [PMID: 28141838 PMCID: PMC5283728 DOI: 10.1371/journal.pone.0171286] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 01/19/2017] [Indexed: 12/01/2022] Open
Abstract
Background Experimental manipulations of floral nectar in food deceptive species can reveal insights into the evolutionary consequences of the deceptive strategy. When coupled to pollen tracking, the effects of the deceptive pollination syndrome on both male and female reproductive success may be quantified. Attraction of pollinators in deceit-pollinated species often relies on producing a conspicuous floral display which may increase visibility to pollinators, but in-turn may increase within plant selfing. Methodology To understand the role of deception in Orchidaceae reproduction we studied Cypripedium candidum. All species of the Cypripedium genus employ a generalized food deceptive pollination strategy and have been suggested as a model system for the study of pollinator deception. We conducted a nectar addition experiment that randomly assigned the four plants closest to a transect point to receive one of four histochemical dyes. Two individuals selected for nectar addition in each of altogether 25 blocks received 2μl of 25% sucrose solution in the labellum of each flower, while two others received no artificial nectar. Number of fruits produced, fruit mass and fruit abortion were scored at the end of the four-month experiment. Results Nectar addition increased (p<0.0001) self-pollination and pollen discounting by nearly 3x, while plants not receiving nectar had greater (p<0.0001) numbers of non-self pollinia deposited and lower rates of pollen discounting. There was a non-significant (p = 0.0645) trend for deceptive plants to set more fruit, while presence of nectar did not affect pollen export. Conclusions This study demonstrates the adaptive advantages of food deception by showing a concurrent reduction in particular male and female functions when a food reward is restored to a deceptive flower. We found generalized food deception to not only decrease inbreeding depression in the system, but concurrently have no effect on pollinator attraction and fruit set when compared with rewarding flowers.
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20
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Hobbhahn N, Johnson SD, Harder LD. The mating consequences of rewarding vs. deceptive pollination systems: Is there a quantity-quality trade-off? ECOL MONOGR 2016. [DOI: 10.1002/ecm.1235] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Nina Hobbhahn
- School of Life Sciences; University of KwaZulu-Natal; Pietermaritzburg 3201 South Africa
- Department of Biological Sciences; University of Calgary; Calgary Alberta T2N 1N4 Canada
| | - Steven D. Johnson
- School of Life Sciences; University of KwaZulu-Natal; Pietermaritzburg 3201 South Africa
| | - Lawrence D. Harder
- Department of Biological Sciences; University of Calgary; Calgary Alberta T2N 1N4 Canada
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21
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Experimental fertilization increases amino acid content in floral nectar, fruit set and degree of selfing in the orchid Gymnadenia conopsea. Oecologia 2015; 179:785-95. [DOI: 10.1007/s00442-015-3381-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 06/17/2015] [Indexed: 10/23/2022]
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Whitehead MR, Linde CC, Peakall R. Pollination by sexual deception promotes outcrossing and mate diversity in self-compatible clonal orchids. J Evol Biol 2015; 28:1526-41. [PMID: 26079670 DOI: 10.1111/jeb.12673] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 05/19/2015] [Accepted: 06/10/2015] [Indexed: 11/28/2022]
Abstract
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.
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Affiliation(s)
- M R Whitehead
- Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - C C Linde
- Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - R Peakall
- Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Canberra, ACT, Australia
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Suetsugu K, Naito RS, Fukushima S, Kawakita A, Kato M. Pollination system and the effect of inflorescence size on fruit set in the deceptive orchid Cephalanthera falcata. JOURNAL OF PLANT RESEARCH 2015; 128:585-594. [PMID: 25801274 DOI: 10.1007/s10265-015-0716-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 02/09/2015] [Indexed: 06/04/2023]
Abstract
Larger inflorescences in reward-producing plants can benefit plants by increasing both pollinator attraction and the duration of visits by individual pollinators. However, ultimately, inflorescence size is determined by the balance between the benefits of large inflorescences and the increased cost of geitonogamy. At present, little is known about the relationship between inflorescence size and fecundity in deceptive plants. Given that pollinators are likely to leave inflorescences lacking rewards quickly, it seems unlikely that longer pollinator visits and the risk of geitonogamy would be strong selective pressures in these species, which indicates that pollinator attraction might be the most important factor influencing their inflorescence size. Here we examined the pollination ecology of the deceptive orchid Cephalanthera falcata in order to clarify the effects of inflorescence size on the fruit set of this non-rewarding species. Field observations of the floral visitors showed that C. falcata is pollinated by the andrenid bee Andrena aburana, whilst pollination experiments demonstrated that this orchid species is neither autogamous nor apogamous, but is strongly pollinator dependent. Three consecutive years of field observations revealed that fruit set was positively correlated with the number of flowers per inflorescence. These results provide strong evidence that the nectarless orchid C. falcata benefits from producing larger inflorescences that attract a greater number of innate pollinators. Large inflorescences may have a greater positive effect on fruit set in deceptive plants because a growing number of studies suggest that fruit set in reward-producing plants is usually unaffected by display size.
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Affiliation(s)
- Kenji Suetsugu
- Graduate School of Human and Environmental Studies, Kyoto University, Yoshida-Nihonmatsu-cho, Sakyo, Kyoto, 606-8501, Japan,
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Scopece G, Schiestl FP, Cozzolino S. Pollen transfer efficiency and its effect on inflorescence size in deceptive pollination strategies. PLANT BIOLOGY (STUTTGART, GERMANY) 2015; 17:545-550. [PMID: 25040501 DOI: 10.1111/plb.12224] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Accepted: 05/16/2014] [Indexed: 06/03/2023]
Abstract
Pollination systems differ in pollen transfer efficiency, a variable that may influence the evolution of flower number. Here we apply a comparative approach to examine the link between pollen transfer efficiency and the evolution of inflorescence size in food and sexually deceptive orchids. We examined pollination performance in nine food-deceptive, and eight sexually deceptive orchids by recording pollen removal and deposition in the field. We calculated correlations between reproductive success and flower number (as a proxy for resources allocated during reproductive process), and directional selection differentials were estimated on flower number for four species. Results indicate that sexually deceptive species experience decreased pollen loss compared to food-deceptive species. Despite producing fewer flowers, sexually deceptive species attained levels of overall pollination success (through male and female function) similar to food-deceptive species. Furthermore, a positive correlation between flower number and pollination success was observed in food-deceptive species, but this correlation was not detected in sexually deceptive species. Directional selection differentials for flower number were significantly higher in food compared to sexually deceptive species. We suggest that pollination systems with more efficient pollen transfer and no correlation between pollination success and number of flowers produced, such as sexual deception, may allow the production of inflorescences with fewer flowers that permit the plant to allocate fewer resources to floral displays and, at the same time, limit transpiration. This strategy can be particularly important for ecological success in Mediterranean water-deprived habitats, and might explain the high frequency of sexually deceptive species in these specialised ecosystems.
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Affiliation(s)
- G Scopece
- Department of Biology, University Federico II, Complesso Universitario MSA, Naples, Italy; Institute for Plant Protection, Consiglio Nazionale delle Ricerche, Sesto Fiorentino (FI), Italy
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Gross K, Schiestl FP. Are tetraploids more successful? Floral signals, reproductive success and floral isolation in mixed-ploidy populations of a terrestrial orchid. ANNALS OF BOTANY 2015; 115:263-73. [PMID: 25652914 PMCID: PMC4551083 DOI: 10.1093/aob/mcu244] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 10/07/2014] [Accepted: 10/22/2014] [Indexed: 05/11/2023]
Abstract
BACKGROUND AND AIMS Polyploidization, the doubling of chromosome sets, is common in angiosperms and has a range of evolutionary consequences. Newly formed polyploid lineages are reproductively isolated from their diploid progenitors due to triploid sterility, but also prone to extinction because compatible mating partners are rare. Models have suggested that assortative mating and increased reproductive fitness play a key role in the successful establishment and persistence of polyploids. However, little is known about these factors in natural mixed-ploidy populations. This study investigated floral traits that can affect pollinator attraction and efficiency, as well as reproductive success in diploid and tetraploid Gymnadenia conopsea (Orchidaceae) plants in two natural, mixed-ploidy populations. METHODS Ploidy levels were determined using flow cytometry, and flowering phenology and herbivory were also assessed. Reproductive success was determined by counting fruits and viable seeds of marked plants. Pollinator-mediated floral isolation was measured using experimental arrays, with pollen flow tracked by means of staining pollinia with histological dye. KEY RESULTS Tetraploids had larger floral displays and different floral scent bouquets than diploids, but cytotypes differed only slightly in floral colour. Significant floral isolation was found between the two cytotypes. Flowering phenology of the two cytotypes greatly overlapped, and herbivory did not differ between cytotypes or was lower in tetraploids. In addition, tetraploids had higher reproductive success compared with diploids. CONCLUSIONS The results suggest that floral isolation and increased reproductive success of polyploids may help to explain their successful persistence in mixed-ploidy populations. These factors might even initiate transformation of populations from pure diploid to pure tetraploid.
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Affiliation(s)
- Karin Gross
- Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland
| | - Florian P Schiestl
- Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland
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Jacquemyn H, Brys R. Pollen limitation and the contribution of autonomous selfing to fruit and seed set in a rewarding orchid. AMERICAN JOURNAL OF BOTANY 2015; 102:67-72. [PMID: 25587149 DOI: 10.3732/ajb.1400449] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
UNLABELLED • PREMISE OF THE STUDY Although rewarding orchids are believed to have a high pollination efficiency, pollination success is often low, suggesting that rewarding orchids may be prone to pollen limitation. Assuming that selfing contributes significantly to fruit and seed set (i.e., reproductive assurance) and that the quality of selfed seeds is high (i.e., low inbreeding depression), it can be hypothesized that under these circumstances populations evolve to facultative or even complete self-pollination.• METHODS In this study, we performed emasculation and pollen supplementation experiments in the field to assess the extent of outcross pollen limitation and the contribution of autonomous self-pollination to fruit and seed set in the rewarding orchid Epipactis palustris. Hand-pollinations using cross and self-pollen were performed in the greenhouse to investigate the impact of selfing on seed set and seed quality and to assess the magnitude of inbreeding depression.• KEY RESULTS Fruit set under natural conditions was high: ca. 70% of all flowers set fruit. Percentage fruit set of emasculated plants was 56%, implying that fruit set in about 14% of all flowers was the result of autonomous self-pollination. Pollen supplementation significantly increased fruit and seed set, indicating strong outcross pollen limitation. Hand-pollination with cross pollen resulted in significantly higher seed set and seed quality compared with manual self-pollination, indicating high levels of early inbreeding depression (δ = 0.46 ± 0.08).• CONCLUSIONS Overall, these results indicate that, despite the high pollination efficiency, populations of this rewarding orchid species were strongly pollen limited. Costs of early inbreeding depression, on the other hand, were high, which may prevent rapid evolution of complete selfing.
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Affiliation(s)
- Hans Jacquemyn
- KU Leuven, Biology Department, Plant Conservation and Population Biology, Kasteelpark Arenberg 31, B-3001 Heverlee, Belgium
| | - Rein Brys
- KU Leuven, Biology Department, Plant Conservation and Population Biology, Kasteelpark Arenberg 31, B-3001 Heverlee, Belgium
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Suetsugu K. Autonomous self-pollination and insect visitors in partially and fully mycoheterotrophic species of Cymbidium (Orchidaceae). JOURNAL OF PLANT RESEARCH 2015; 128:115-25. [PMID: 25286768 DOI: 10.1007/s10265-014-0669-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 08/14/2014] [Indexed: 05/12/2023]
Abstract
Few studies have examined the reproductive ecology of mycoheterotrophic plants, but the existing literature hypothesizes that they adopt a self-pollinating strategy. Although growing evidence indicates that some rewarding mycoheterotrophic plants depend (at least partially) on an insect-mediated pollination system, it remains unclear whether some mycoheterotrophic plants can attract pollinators without nectar or other rewards. Moreover, in a broader evolutionary/ecological context, the question of whether the evolution of mycoheterotrophy induces a shift in pollination pattern is still unknown. Here I present a comparative investigation into the breeding system of two fully mycoheterotrophic orchids, Cymbidium macrorhizon and C. aberrans, and their closest extant relative, the mixotrophic C. lancifolium. Pollination experiments were conducted to determine the breeding system of these plants. In addition, flower visitors that might contribute to pollination were recorded. Flowers at different maturity stages were examined to investigate mechanisms enabling or limiting self-fertilization. While nectarless flowers of C. lancifolium and C. macrorhizon can successfully attract potential pollinator honeybees, all three Cymbidium possess an effective self-pollination system in which the rostellum that physically separates the stigma and pollinia is absent. Because mixotrophic and mycoheterotrophic Cymbidium occupy low-light niches, pollinator foraging would be negatively influenced by low-light intensity. In partial and fully mycoheterotrophic Cymbidium, autogamy would likely be favoured as a reproductive assurance to compensate for pollinator limitation due to their lack of nectar and pollinators' hostile habitat preferences.
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Affiliation(s)
- Kenji Suetsugu
- Graduate School of Human and Environmental Studies, Kyoto University, Yoshida-Nihonmatsu-cho, Sakyo, Kyoto, 606-8501, Japan,
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Liao WJ, Harder LD. Consequences of Multiple Inflorescences and Clonality for Pollinator Behavior and Plant Mating. Am Nat 2014; 184:580-92. [DOI: 10.1086/678117] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Walsh RP, Arnold PM, Michaels HJ. Effects of pollination limitation and seed predation on female reproductive success of a deceptive orchid. AOB PLANTS 2014; 6:plu031. [PMID: 24916060 PMCID: PMC4094650 DOI: 10.1093/aobpla/plu031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 06/02/2014] [Indexed: 06/03/2023]
Abstract
For many species of conservation significance, multiple factors limit reproduction. This research examines the contributions of plant height, number of flowers, number of stems, pollen limitation and seed predation to female reproductive success in the deceit-pollinated orchid, Cypripedium candidum. The deceptive pollination strategy employed by many orchids often results in high levels of pollen limitation. While increased floral display size may attract pollinators, C. candidum's multiple, synchronously flowering stems could promote selfing and also increase attack by weevil seed predators. To understand the joint impacts of mutualists and antagonists, we examined pollen limitation, seed predation and the effects of pollen source over two flowering seasons (2009 and 2011) in Ohio. In 2009, 36 pairs of plants size-matched by flower number, receiving either supplemental hand or open pollination, were scored for fruit maturation, mass of seeds and seed predation. Pollen supplementation increased proportion of flowers maturing into fruit, with 87 % fruit set when hand pollinated compared with 46 % for naturally pollinated flowers. Inflorescence height had a strong effect, as taller inflorescences had higher initial fruit set, while shorter stems had higher predation. Seed predation was seen in 73 % of all fruits. A parallel 2011 experiment that included a self-pollination treatment and excluded seed predators found initial and final fruit set were higher in the self and outcross pollination treatments than in the open-pollinated treatment. However, seed mass was higher in both open pollinated and outcross pollination treatments compared with hand self-pollinated. We found greater female reproductive success for taller flowering stems that simultaneously benefited from increased pollination and reduced seed predation. These studies suggest that this species is under strong reinforcing selection to increase allocation to flowering stem height. Our results may help explain the factors limiting seed production in other Cypripedium and further emphasize the importance of management in orchid conservation.
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Affiliation(s)
- Ryan P Walsh
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43402, USA
| | - Paige M Arnold
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43402, USA
| | - Helen J Michaels
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43402, USA
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Stabilizing selection on nectar concentration in wild Petunia axillaris, as revealed by genetic analysis of pollen dispersal. Evol Ecol 2014. [DOI: 10.1007/s10682-014-9714-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Selosse MA. The latest news from biological interactions in orchids: in love, head to toe. THE NEW PHYTOLOGIST 2014; 202:337-340. [PMID: 24645780 DOI: 10.1111/nph.12769] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
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Broom M, Ruxton GD, Schaefer HM. Signal verification can promote reliable signalling. Proc Biol Sci 2013; 280:20131560. [PMID: 24068354 DOI: 10.1098/rspb.2013.1560] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The central question in communication theory is whether communication is reliable, and if so, which mechanisms select for reliability. The primary approach in the past has been to attribute reliability to strategic costs associated with signalling as predicted by the handicap principle. Yet, reliability can arise through other mechanisms, such as signal verification; but the theoretical understanding of such mechanisms has received relatively little attention. Here, we model whether verification can lead to reliability in repeated interactions that typically characterize mutualisms. Specifically, we model whether fruit consumers that discriminate among poor- and good-quality fruits within a population can select for reliable fruit signals. In our model, plants either signal or they do not; costs associated with signalling are fixed and independent of plant quality. We find parameter combinations where discriminating fruit consumers can select for signal reliability by abandoning unprofitable plants more quickly. This self-serving behaviour imposes costs upon plants as a by-product, rendering it unprofitable for unrewarding plants to signal. Thus, strategic costs to signalling are not a prerequisite for reliable communication. We expect verification to more generally explain signal reliability in repeated consumer-resource interactions that typify mutualisms but also in antagonistic interactions such as mimicry and aposematism.
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Affiliation(s)
- Mark Broom
- Department of Mathematics, City University London, , London EC1V 0HB, UK, School of Biology, University of St Andrews, , St Andrews KY16 9TH, UK, Faculty of Biology, Department of Evolutionary Biology and Animal Ecology, University of Freiburg, , Hauptstrasse 1, 79104 Freiburg, Germany
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Poor correlation between the removal or deposition of pollen grains and frequency of pollinator contact with sex organs. Naturwissenschaften 2013; 100:871-6. [PMID: 23928839 DOI: 10.1007/s00114-013-1087-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 07/25/2013] [Accepted: 07/26/2013] [Indexed: 10/26/2022]
Abstract
Pollinators deposit pollen grains on stigmas and remove pollen grains from anthers. The mechanics of these transfers can now be quantified with the use of high-speed video. We videoed hawkmoths, carpenter bees, and swallowtail butterflies pollinating Clerodendrum trichotomum. The number of grains deposited on stigmas did not vary significantly with the number of times pollinators contacted stigmas. In contrast, pollen removal from the anthers increased significantly with the number of contacts to anthers. Pollen removal varied among the three types of pollinators. Also, the three types carried pollen on different parts of their bodies. In hawkmoths and carpenter bees, a large number of contacted body part with anthers differed significantly from the body part that attached a large number of pollen grains. Our results indicate that a large number of contacts by pollinators does not increase either the male or female reproductive success of plants compared to a small number of contacts during a visit.
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Jacquemyn H, Lenaerts M, Tyteca D, Lievens B. Microbial diversity in the floral nectar of seven Epipactis (Orchidaceae) species. Microbiologyopen 2013; 2:644-58. [PMID: 23836678 PMCID: PMC3948608 DOI: 10.1002/mbo3.103] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 05/23/2013] [Accepted: 05/28/2013] [Indexed: 11/16/2022] Open
Abstract
Floral nectar of animal-pollinated plants is commonly infested with microorganisms, yet little is known about the microorganisms inhabiting the floral nectar of orchids. In this study, we investigated microbial communities occurring in the floral nectar of seven Epipactis (Orchidaceae) species. Culturable bacteria and yeasts were isolated and identified by partially sequencing the small subunit (SSU) ribosomal RNA (rRNA) gene and the D1/D2 domains of the large subunit (LSU) rRNA gene, respectively. Using three different culture media, we found that bacteria were common inhabitants of the floral nectar of Epipactis. The most widely distributed bacterial operational taxonomic units (OTUs) in nectar of Epipactis were representatives of the family of Enterobacteriaceae, with an unspecified Enterobacteriaceae bacterium as the most common. In contrast to previous studies investigating microbial communities in floral nectar, very few yeast species (mainly of the genus Cryptococcus) were observed, and most of them occurred in very low densities. Total OTU richness (i.e., the number of bacterial and yeast OTUs per orchid species) varied between 4 and 20. Cluster analysis revealed that microbial communities of allogamous species differed from those of autogamous and facultatively autogamous species. This study extends previous efforts to identify microbial communities in floral nectar and indicates that the floral nectar of the orchids investigated mainly contained bacterial communities with moderate phylogenetic diversity.
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MESH Headings
- Bacteria/classification
- Bacteria/genetics
- Bacteria/growth & development
- Bacteria/isolation & purification
- Biodiversity
- Cluster Analysis
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- DNA, Fungal/chemistry
- DNA, Fungal/genetics
- DNA, Ribosomal/chemistry
- DNA, Ribosomal/genetics
- Fungi/classification
- Fungi/genetics
- Fungi/growth & development
- Fungi/isolation & purification
- Genes, rRNA
- Molecular Sequence Data
- Orchidaceae/microbiology
- Phylogeny
- Plant Nectar
- RNA, Bacterial/genetics
- RNA, Fungal/genetics
- RNA, Ribosomal, 16S/genetics
- RNA, Ribosomal, 18S/genetics
- Sequence Analysis, DNA
- Sequence Homology, Nucleic Acid
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Affiliation(s)
- Hans Jacquemyn
- Plant Conservation and Population Biology Biology Department, KU LeuvenKasteelpark Arenberg 31, B-3001, Heverlee, Belgium
| | - Marijke Lenaerts
- Laboratory for Process Microbial Ecology and Bioinspirational Management (PME&BIM), Thomas More University College, De Nayer Campus Department of Microbial and Molecular Systems (MS), KU Leuven AssociationB-2860, Sint-Katelijne-Waver, Belgium
- Scientia Terrae Research InstituteB-2860 Sint-Katelijne-Waver, Belgium
| | - Daniel Tyteca
- Biodiversity Research Centre Earth and Life Institute, Université catholique de LouvainB-1348, Louvain-la-Neuve, Belgium
| | - Bart Lievens
- Laboratory for Process Microbial Ecology and Bioinspirational Management (PME&BIM), Thomas More University College, De Nayer Campus Department of Microbial and Molecular Systems (MS), KU Leuven AssociationB-2860, Sint-Katelijne-Waver, Belgium
- Scientia Terrae Research InstituteB-2860 Sint-Katelijne-Waver, Belgium
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Johnson SD, Hobbhahn N, Bytebier B. Ancestral deceit and labile evolution of nectar production in the African orchid genus Disa. Biol Lett 2013; 9:20130500. [PMID: 23904568 DOI: 10.1098/rsbl.2013.0500] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
An outstanding feature of the orchid family is that approximately 30-40% of the species have non-rewarding flowers and deploy various modes of deception to attract pollinators, whereas the remaining species engage in pollination mutualisms based on provision of floral rewards. Here, we explore the direction, frequency and reversibility of transitions between deceptive and rewarding pollination systems in the radiation of the large African genus Disa, and test whether these transitions had consequences for diversification. By optimizing nectar production data for 111 species on a well-resolved phylogeny, we confirmed that floral deception was the ancestral condition and that nectar production evolved at least nine times and was lost at least once. Transitions to nectar production first occurred ca 17 million years ago but did not significantly affect either speciation or extinction rates. Nectar evolved independently of a spur, which was lost and gained multiple times. These results show that nectar production can be a highly labile trait and highlight the need for further studies of the genetic architecture of nectar production and the selective factors underlying transitions between deception and mutualism.
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Affiliation(s)
- Steven D Johnson
- School of Life Sciences, University of KwaZulu-Natal, Scottsville, Pietermaritzburg 3209, South Africa.
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36
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Schiestl FP, Johnson SD. Pollinator-mediated evolution of floral signals. Trends Ecol Evol 2013; 28:307-15. [PMID: 23480953 DOI: 10.1016/j.tree.2013.01.019] [Citation(s) in RCA: 302] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 01/30/2013] [Accepted: 01/30/2013] [Indexed: 12/27/2022]
Abstract
Because most plants rely on animals for pollination, insights from animal sensory ecology and behavior are essential for understanding the evolution of flowers. In this review, we compare and contrast three main types of pollinator responses to floral signals--receiver bias, 'adaptive' innate preferences, and associative learning--and discuss how they can shape selection on floral signals. We show that pollinator-mediated selection on floral signals can be strong and that the molecular bases of floral signal variation are often surprisingly simple. These new empirical and conceptual insights into pollinator-mediated evolution provide a framework for understanding patterns of both convergent (pollination syndromes) and advergent (floral mimicry) floral signal evolution.
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Affiliation(s)
- Florian P Schiestl
- Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland.
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Schaeffer RN, Manson JS, Irwin RE. Effects of abiotic factors and species interactions on estimates of male plant function: a meta-analysis. Ecol Lett 2012; 16:399-408. [DOI: 10.1111/ele.12044] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 10/16/2012] [Accepted: 11/03/2012] [Indexed: 11/27/2022]
Affiliation(s)
- Robert N. Schaeffer
- Department of Biological Sciences; Dartmouth College; Hanover; NH; 03755; USA
| | | | - Rebecca E. Irwin
- Department of Biological Sciences; Dartmouth College; Hanover; NH; 03755; USA
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39
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Henning T, Weigend M. Total control - pollen presentation and floral longevity in Loasaceae (blazing star family) are modulated by light, temperature and pollinator visitation rates. PLoS One 2012; 7:e41121. [PMID: 22916102 PMCID: PMC3423403 DOI: 10.1371/journal.pone.0041121] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 06/19/2012] [Indexed: 11/18/2022] Open
Abstract
Stamen movements can be understood as a mechanism influencing pollen presentation and increasing outbreeding success of hermaphroditic flowers via optimized male function. In this study we experimentally analyzed the factors regulating autonomous and thigmonastic (triggered by flower visitors) stamen movements in eight species of Loasaceae. Both types of stamen movements are positively influenced by light and temperature and come to a virtual standstill in the dark and at low temperatures (12°C). Pollen presentation is thus discontinued during periods where pollinators are not active. Overall stamen presentation increases with increasing flower age. Contrary to expectation, no geometrical correlation between the floral scale stimulated and the stamen fascicle reacting exists, indicating that the stimulus is transmitted over the receptacle and stamen maturation dictates which and how many stamens react. Thigmonastic stamen presentation is dramatically accelerated compared to autonomous movement (3–37 times), indicating that the rate of stamen maturation can be adjusted to different visitation schedules. Flowers can react relatively uniformly down to stimulation intervals of 10–15 min., consistently presenting comparable numbers of stamens in the flower c. 5 min. after the stimulus and can thus keep the amount of pollen presented relatively constant even under very high visitation frequencies of 4–6 visits/h. Thigmonastic pollen presentation dramatically reduces the overall duration of the staminate phase (to 1/3rd in Nasa macrothyrsa). Similarly, the carpellate phase is dramatically reduced after pollination, down to 1 d from 4 d. Overall flower longevity is reduced by more than 2/3rds under high visitation rates (<3 d versus 10 d under visitor exclusion) and depleted and pollinated flowers are rapidly removed from the pool. Complex floral behaviour in Loasaceae thus permits a near-total control over pollen dispensation schedules and floral longevity of the individual flower by an extraordinary fine-tuning to both biotic and abiotic factors.
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Affiliation(s)
- Tilo Henning
- Institut für Biologie, Morphologie und Systematik der Phanerogamen, Freie Universität Berlin, Berlin, Germany.
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40
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Recart W, Ackerman JD, Cuevas AA. There goes the neighborhood: apparent competition between invasive and native orchids mediated by a specialist florivorous weevil. Biol Invasions 2012. [DOI: 10.1007/s10530-012-0283-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Xiaohua J, Dezhu L, Zongxin R, Xiaoguo X. A generalized deceptive pollination system of Doritis pulcherrima (Aeridinae: Orchidaceae) with non-reconfigured pollinaria. BMC PLANT BIOLOGY 2012; 12:67. [PMID: 22571550 PMCID: PMC3388949 DOI: 10.1186/1471-2229-12-67] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Accepted: 05/09/2012] [Indexed: 05/11/2023]
Abstract
BACKGROUND As one of largest angiosperm families, orchids have long fascinated evolutionary biologists with their staggering diversity in floral design and display to promote outcrossing. Two of the most intriguing aspects of orchid pollination that promote cross-pollination are pollinarium reconfiguration (PR) and deceptive pollination. PR and generalized food deception employ virtually antagonistic methods of promoting cross-pollination: PR occurs through delayed pollination, involving the relatively long visitation periods that are typically observed for the pollinators of one flower or inflorescence; conversely, generalized food deception leads to reductions in the visitation periods of pollinators to one flower or inflorescence. Thus, it is logical to hypothesize that PR is unnecessary or PR happens soon in generalized food-deceptive orchids in the promotion of cross-pollination. Using Doritis pulcherrima as a model, the aim of this study was to understand the following: (1) the pollination and breeding system of D. pulcherrima; (2) the morphological interactions between orchids and their pollinators; and (3) whether PR is necessary in the promotion of cross-pollination in D. pulcherrima. RESULTS Our observations indicated that Doritis pulcherrima is pollinated almost exclusively by Amegilla nigritar (Hymenoptera: Apidae) and possesses pollinia that are deposited on the "occiputs" (cervical membranes) of these insects. All of evidences are indicated that D. pulcherrima is a generalized food-deceptive orchid. Our morphometric measurements of the flowers and pollinators show that the heights of the "occiputs" with un-oriented pollinaria were equal to the distances between stigmas and surfaces of the middle lobes, suggesting that pollinarium reconfiguration is not necessary in Doritis pulcherrima. CONCLUSIONS Our observation and analyses supported the hypothesis that pollinarium reconfiguration is unnecessary in generalized food-deceptive orchids, such as Doritis pulcherrima, for the promotion of cross-pollination. This conclusion was indirectly supported by the abundance of deceptive orchids that do not exhibit pollinarium reconfiguration. There are two mechanisms (i.e. clone-growing characteristics and a long flowering season) that promote fruit sets in the epiphytic food-deceptive orchids in tropical regions.
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Affiliation(s)
- Jin Xiaohua
- State Key Laboratory of Systematic and Evolutionary Botany & Herbarium, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Li Dezhu
- Plant Germplasm and Genomics Center, Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, 650201, China
| | - Ren Zongxin
- Plant Germplasm and Genomics Center, Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, 650201, China
| | - Xiang Xiaoguo
- State Key Laboratory of Systematic and Evolutionary Botany & Herbarium, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
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Coombs G, Dold AP, Brassine EI, Peter CI. Large pollen loads of a South African asclepiad do not interfere with the foraging behaviour or efficiency of pollinating honey bees. Naturwissenschaften 2012; 99:545-52. [DOI: 10.1007/s00114-012-0932-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 06/10/2012] [Accepted: 06/12/2012] [Indexed: 10/28/2022]
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Sletvold N, Grindeland JM, Zu P, Ågren J. Strong inbreeding depression and local outbreeding depression in the rewarding orchid Gymnadenia conopsea. CONSERV GENET 2012. [DOI: 10.1007/s10592-012-0373-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Wiemer AP, Sérsic AN, Marino S, Simões AO, Cocucci AA. Functional morphology and wasp pollination of two South American asclepiads (Asclepiadoideae-Apocynaceae). ANNALS OF BOTANY 2012; 109:77-93. [PMID: 22025522 PMCID: PMC3241588 DOI: 10.1093/aob/mcr268] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
UNLABELLED BACKGROUND AND AIMS The extreme complexity of asclepiad flowers (Asclepiadoideae-Apocynaceae) has generated particular interest in the pollination biology of this group of plants especially in the mechanisms involved in the pollination processes. This study compares two South American species, Morrenia odorata and Morrenia brachystephana, with respect to morphology and anatomy of flower structures, dynamic aspects of the pollination mechanism, diversity of visitors and effectiveness of pollinators. METHODS Floral structure was studied with fresh and fixed flowers following classical techniques. The pollination mechanism was studied by visiting fresh flowers in the laboratory with artificial pollinator body parts created with an eyelash. Morphometric and nectar measurements were also taken. Pollen transfer efficiency in the flowers was calculated by recording the frequency of removed and inserted pollinia. Visitor activity was recorded in the field, and floral visitors were captured for subsequent analysis of pollen loads. Finally, pollinator effectiveness was calculated with an index. KEY RESULTS The detailed structure of the flowers revealed a complex system of guide rails and chambers precisely arranged in order to achieve effective pollinaria transport. Morrenia odorata is functionally specialized for wasp pollination, and M. brachystephana for wasp and bee pollination. Pollinators transport chains of pollinaria adhered to their mouthparts. CONCLUSIONS Morrenia odorata and M. brachystephana present differences in the morphology and size of their corona, gynostegium and pollinaria, which explain the differences in details of the functioning of the general pollination mechanism. Pollination is performed by different groups of highly effective pollinators. Morrenia species are specialized for pollination mainly by several species of wasps, a specialized pollination which has been poorly studied. In particular, pompilid wasps are reported as important pollinators in other regions outside South Africa. A putative new function of nectar in asclepiads is presented, as it would be contributing to the pollination mechanism.
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Affiliation(s)
- A P Wiemer
- Laboratorio de Biología Floral (IMBIV-CONICET-UNCba), CC 495, CP 5000, Córdoba, Argentina.
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Juillet N, Salzmann CC, Scopece G. Does facilitating pollinator learning impede deceptive orchid attractiveness? A multi-approach test of avoidance learning. PLANT BIOLOGY (STUTTGART, GERMANY) 2011; 13:570-575. [PMID: 21668597 DOI: 10.1111/j.1438-8677.2010.00421.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
It has often been proposed that nectarless deceptive orchid species exploit naïve pollinators in search of food before they learn to avoid their flowers, and that intraspecific floral trait polymorphism, often noted in this plant group, could prolong the time needed for learning, thus increasing orchid reproductive success. We tested the importance of avoidance learning in a European deceptive orchid, Anacamptis morio, which has been reported to have a highly variable fragrance bouquet among individuals. We used an indirect approach, i.e. we facilitated pollinators' ability to learn to avoid A. morio by adding anisaldehyde to selected inflorescences, a scent compound that is easily perceived by the natural pollinators and produced in large quantities by the closely related, nectar producing Anacamptis coriophora, a species that shares pollinator species with A. morio. In a series of three experiments (in artificial arrays, in natural populations and in bumblebee behavioural observations), we consistently found no difference either of reproductive success of or visitation rates to scent-added versus control inflorescences. We also found that the decrease of reproductive success over time in artificial populations of this deceptive species was not as important as expected. Together, these data suggest that pollinators do not fully learn to avoid deceptive inflorescences, and that pollinator avoidance behaviour alone may explain the lower reproductive success usually found in deceptive orchids. We discuss the possible explanations for this pattern in deceptive orchids, particularly in relation to pollinator cognition and learning abilities. Lastly, in light of our results, the potential for higher average reproductive success in deceptive orchids with high phenotypic variability driven by avoidance learning thus appears to be challenged.
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Affiliation(s)
- N Juillet
- Dipartimento di Biologia Strutturale e Funzionale, Università degli Studi di Napoli Federico II, Complesso Universitario MSA, via Cinthia 1-80, Naples, Italy.
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Ellis AG, Johnson SD. Floral mimicry enhances pollen export: the evolution of pollination by sexual deceit outside of the orchidaceae. Am Nat 2011; 176:E143-51. [PMID: 20843263 DOI: 10.1086/656487] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Although the majority of flowering plants achieve pollination by exploiting the food‐seeking behavior of animals, some use alternative ploys that exploit their mate‐seeking behavior. Sexual deception is currently known only from the Orchidaceae and almost always involves pollination by male hymenoptera. An outstanding problem has been to identify the selective factors in plants that favor exploitation of mating versus feeding behaviors in pollinators. Here we show that the insectlike petal ornaments on inflorescences of the daisy Gorteria diffusa elicit copulation attempts from male bombyliid flies and that the intensity of the mating response varies across geographical floral morphotypes, suggesting a continuum in reliance on feeding through mating responses for pollination. Using pollen analogues applied to a morphotype with prominent insectlike petal ornaments, we demonstrate that mate‐seeking male flies are several‐fold more active and export significantly more pollen than females. These results suggest that selection for traits that exploit insect mating behavior can occur through the male component of plant fitness and conclusively demonstrates pollination by sexual deception in Gorteria, making this the first confirmed report of sexual deception outside of the Orchidaceae.
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Affiliation(s)
- Allan G Ellis
- School of Biological and Conservation Sciences, University of KwaZulu‐Natal, Scottsville, Pietermaritzburg 3209, South Africa.
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Vale A, Rojas D, Alvarez JC, Navarro L. Breeding system and factors limiting fruit production in the nectarless orchid Broughtonia lindenii. PLANT BIOLOGY (STUTTGART, GERMANY) 2011; 13 Suppl 1:51-61. [PMID: 21134087 DOI: 10.1111/j.1438-8677.2010.00366.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Low fruit set values in most orchids (especially epiphytic and tropical species) are normally thought to be the consequence of pollination constraints and limited resources. In particular, pollination constraints are modulated by pollinator visitation rates, pollinator visitation behaviour (promoting crossing or selfing), the type and number of pollinia deposited on stigmas (in the case of orchids with subequal pollinia) and the amount of pollen loaded per inflorescence. In order to assess to what extent these factors can affect fruit set in specific orchid-pollinator systems, the repercussions of some of these aspects on reproduction of Broughtonia lindenii were examined in a coastal population in western Cuba. The study focused on plant breeding system, importance of pollen load and type of pollinia on subsequent fruit and seed, limiting factors of seed production and interaction with pollinators. This species presents long-lasting flowers that senesce after all forms of effective visit. Pollinator dependence for fruit production was demonstrated, while hand-pollination experiments revealed self-compatibility and inbreeding depression at seed level. More pollinia on stigmas enhance the proportion of well-developed seeds. In contrast, the pollinia type used in pollination is not important for seed quality of fruits, suggesting that small pollinia are not rudimentary. Natural fruit set in two consecutive years was substantially affected by pollinator activity, and also by systematic depredatory activity of ants and a caterpillar. Considering that this orchid completely lacks nectar and that the local assemblage of pollinators and predators influenced its reproduction, a minor importance of resource constraints in this epiphyte (with long-lasting reserve structures) is confirmed at least for a short time.
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Affiliation(s)
- A Vale
- Departamento de Biología Vegetal y Ciencias del Suelo, Universidad de Vigo, Vigo, España
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Sletvold N, Grindeland JM, Agren J. Pollinator-mediated selection on floral display, spur length and flowering phenology in the deceptive orchid Dactylorhiza lapponica. THE NEW PHYTOLOGIST 2010; 188:385-392. [PMID: 20497348 DOI: 10.1111/j.1469-8137.2010.03296.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
• Nonrewarding animal-pollinated plants commonly experience severe pollen limitation, which should result in strong selection on traits affecting the success of pollination. However, the importance of pollinators as selective agents on floral traits in deceptive species has not been quantified experimentally. • Here, we quantified pollinator-mediated selection (Δβ(poll)) on floral morphology and start of flowering in the deceptive orchid Dactylorhiza lapponica by subtracting estimates of selection gradients for plants receiving supplemental hand-pollination from estimates obtained for open-pollinated control plants. • There was directional selection for taller plants with more flowers and longer spurs, but no statistically significant selection on corolla size or flowering start. Pollinator-mediated selection accounted for all observed selection on spur length (Δβ(poll) = 0.32), 76% of the selection on plant height (Δβ(poll) = 0.19) and 42% of the selection on number of flowers (Δβ(poll = 0.30). Sixteen per cent of developing fruits were consumed by insect herbivores, but fruit herbivory had only minor effects on the strength of pollinator-mediated selection. • Our results demonstrate that pollinators mediate selection on floral traits likely to affect both pollinator attraction and pollination efficiency, and are consistent with the hypothesis that deceptive species experience strong selection for increased display and mechanical fit between flower and pollinator.
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Affiliation(s)
- Nina Sletvold
- NTNU, Museum of Natural History and Archaeology, Trondheim, Norway.
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Aximoff IA, Freitas L. Is pollen removal or seed set favoured by flower longevity in a hummingbird-pollinated Salvia species? ANNALS OF BOTANY 2010; 106:413-9. [PMID: 20622254 PMCID: PMC2924834 DOI: 10.1093/aob/mcq141] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
BACKGROUND AND AIMS The period between the beginning of anthesis and flower senescence modulates the transport of pollen by pollinators among conspecific flowers, and its length may therefore influence reproductive success. This study evaluated whether floral longevity favours pollen removal from the anthers over fecundity (seed set) in an ornithophilous species that does not undergo pollen limitation. METHODS Field investigations were conducted on floral longevity, nectar production, pollinator behaviour, and variations in fruit set (FS), mean number of seeds per fruit (MSF) and pollen removal by hummingbirds (PR) during the anthesis of Salvia sellowiana in south-east Brazil. KEY RESULTS Anthesis of flowers exposed to pollinators lasted 4 d, as well as on flowers with pollen removed from the anthers or deposited on the stigma. The longevity of bagged flowers was significantly higher (approx. 9 d). FS and PR reached 87.2 and 90 %, respectively, in natural conditions. PR increased gradually over the period of anthesis; however, FS and MSF reached their maxima in the first hours of anthesis. Nectar production was continuous, but the secretion rate was reduced after pollination. The removal of nectar from non-pollinated flowers stimulated its production. CONCLUSIONS The longevity of anthesis in S. sellowiana seems to be related to the mechanism of gradual dispensing of pollen, resulting in greater male reproductive success. This is in agreement with the pollen-donation hypothesis. The small number of ovules (four) of S. sellowiana and the high frequency and the foraging mode of its pollinators may favour the selection for floral longevity driven by male fitness in this system.
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Schatz B, Geoffroy A, Dainat B, Bessière JM, Buatois B, Hossaert-McKey M, Selosse MA. A case study of modified interactions with symbionts in a hybrid mediterranean orchid. AMERICAN JOURNAL OF BOTANY 2010; 97:1278-88. [PMID: 21616880 DOI: 10.3732/ajb.0900303] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
PREMISE OF THE STUDY Most studies on orchid hybrids examine separately the effects of hybridization on interactions with pollinators or with mycorrhizal fungi. Here, we simultaneously investigated both interactions in the mediterranean food-deceptive Orchis simia, O. anthropophora, and their hybrid (O. ×bergonii) and tested a possible breakdown of coevolution using a multidisciplinary approach. • METHODS We compared leaf growth, seed viability, emitted scent, and mycorrhizal fungi (species and rate of infection) among these three taxa. • KEY RESULTS We show that leaf surface is greater in adult hybrids than in the parental species, suggesting a heterosis effect for vegetative growth. We demonstrate that flowers of the two parental species emit well-differentiated bouquets of volatile organic compounds, while hybrids emit larger quantities, accumulating most compounds of the two parental species. However, hybrids fail to attract pollinators and have a 10 times lower fruit set. We determined that closely related Tulasnellales are mycorrhizal in the three taxa, suggesting that the mycorrhizal partner does not impair hybrid survival. We propose an interpretative model for O. ×bergonii compared with its parents. • CONCLUSIONS In hybrids, carbon resources normally devoted to reproduction may be reallocated to the mycorrhizal symbiosis as a result of the disruption of the pollination interaction in hybrids. Higher mycorrhizal infection may in turn enhance vegetative growth and scent emission. Such interplay between the two obligate biotic interactions yields new insights into hybridization among orchids.
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Affiliation(s)
- Bertrand Schatz
- Equipe Interactions Biotiques, Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), UMR CNRS 5175, 1919 route de Mende, F-34293 Montpellier Cedex 5, France
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