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Wang X, Cai J, Tong M, Shi M, Zhao Z, Li S, Tu T. Heterospecific pollen avoidance strategy prevails in the generalized plant-pollinator network on Yongxing Island. Ecol Evol 2024; 14:e11123. [PMID: 38444723 PMCID: PMC10912527 DOI: 10.1002/ece3.11123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2023] [Revised: 02/19/2024] [Accepted: 02/25/2024] [Indexed: 03/07/2024] Open
Abstract
Heterospecific pollen (HP) deposition varies widely among species in communities, which has been explicated by two adaptation strategies: HP avoidance and HP tolerance. Studies of the plant-pollinator network have uncovered that oceanic island communities are highly generalized and strongly connected. It remains unclear, however, which strategy prevails in such communities. We examined stigma pollen deposition on 29 plant species, and assessed patterns of HP load size and diversity in the Yongxing Island community. We assessed the effects of phenotypic specialization and species-level network structural properties of plant species on pollen deposition among species. The hypothesis of three accrual patterns of HP within species was tested by illustrating the relationship between conspecific pollen (CP) and HP receipt. Extensive variation occurred among species in HP receipt, while 75.9% of species received less than 10% HP and one species received more than 40% HP throughout the community. Flower size strongly drives the variation of HP receipt, while network structural properties had no effect on the pollen receipt. Nineteen species showed no relationship between the number of HP and CP loads, and they received smaller HP load sizes and lower HP proportions. Most plant species evolved HP avoidance strategy, and HP receipt was an occasional event for most plant species in the generalized community. HP and CP receipts are independent of each other in plant species with the HP avoidance mechanism. Our results highlight that plants in the generalized pollination system may preferentially select to minimize the HP load on stigmas.
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Affiliation(s)
- Xiang‐Ping Wang
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical GardenChinese Academy of SciencesGuangzhouChina
- South China National Botanical GardenGuangzhouChina
| | - Jin‐Chao Cai
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical GardenChinese Academy of SciencesGuangzhouChina
- South China National Botanical GardenGuangzhouChina
- Gannan Normal UniversityGanzhouChina
| | - Ma‐Yin Tong
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical GardenChinese Academy of SciencesGuangzhouChina
- South China National Botanical GardenGuangzhouChina
- University of Chinese Academy of SciencesBeijingChina
| | - Miao‐Miao Shi
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical GardenChinese Academy of SciencesGuangzhouChina
- South China National Botanical GardenGuangzhouChina
| | - Zhong‐Tao Zhao
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical GardenChinese Academy of SciencesGuangzhouChina
- South China National Botanical GardenGuangzhouChina
| | - Shi‐Jin Li
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical GardenChinese Academy of SciencesGuangzhouChina
- South China National Botanical GardenGuangzhouChina
| | - Tie‐Yao Tu
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical GardenChinese Academy of SciencesGuangzhouChina
- South China National Botanical GardenGuangzhouChina
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Stanley A, Martel C, Arceo-Gómez G. Spatial variation in bidirectional pollinator-mediated interactions between two co-flowering species in serpentine plant communities. AOB PLANTS 2021; 13:plab069. [PMID: 34804469 PMCID: PMC8598379 DOI: 10.1093/aobpla/plab069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 10/19/2021] [Indexed: 06/13/2023]
Abstract
Pollinator-mediated competition and facilitation are two important mechanisms mediating co-flowering community assembly. Experimental studies, however, have mostly focused on evaluating outcomes for a single interacting partner at a single location. Studies that evaluate spatial variation in the bidirectional effects between co-flowering species are necessary if we aim to advance our understanding of the processes that mediate species coexistence in diverse co-flowering communities. Here, we examine geographic variation (i.e. at landscape level) in bidirectional pollinator-mediated effects between co-flowering Mimulus guttatus and Delphinium uliginosum. We evaluated effects on pollen transfer dynamics (conspecific and heterospecific pollen deposition) and plant reproductive success. We found evidence of asymmetrical effects (one species is disrupted and the other one is facilitated) but the effects were highly dependent on geographical location. Furthermore, effects on pollen transfer dynamics did not always translate to effects on overall plant reproductive success (i.e. pollen tube growth) highlighting the importance of evaluating effects at multiple stages of the pollination process. Overall, our results provide evidence of a spatial mosaic of pollinator-mediated interactions between co-flowering species and suggest that community assembly processes could result from competition and facilitation acting simultaneously. Our study highlights the importance of experimental studies that evaluate the prevalence of competitive and facilitative interactions in the field, and that expand across a wide geographical context, in order to more fully understand the mechanisms that shape plant communities in nature.
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Affiliation(s)
- Amber Stanley
- Department of Biological Sciences, East Tennessee State University, Johnson City, TN 37614, USA
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Carlos Martel
- Department of Biological Sciences, East Tennessee State University, Johnson City, TN 37614, USA
- Instituto de Ciencias Ómicas y Biotecnología Aplicada, Pontificia Universidad Católica del Perú, San Miguel 15088, Lima, Peru
| | - Gerardo Arceo-Gómez
- Department of Biological Sciences, East Tennessee State University, Johnson City, TN 37614, USA
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3
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Smith GX, Swartz MT, Spigler RB. Causes and consequences of variation in heterospecific pollen receipt in Oenothera fruticosa. AMERICAN JOURNAL OF BOTANY 2021; 108:1612-1624. [PMID: 34460097 PMCID: PMC9291898 DOI: 10.1002/ajb2.1720] [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: 02/12/2021] [Accepted: 05/25/2021] [Indexed: 05/05/2023]
Abstract
PREMISE Heterospecific pollen transfer, the transfer of pollen between species, is common among co-flowering plants, yet the amount of pollen received is extremely variable among species. Intraspecific variation in heterospecific pollen receipt can be even greater, but we lack an understanding of its causes and fitness consequences in wild populations. METHODS We examined potential drivers of variation in heterospecific pollen receipt in Oenothera fruticosa. We evaluated the relationship between heterospecific and conspecific pollen receipt and considered how visitation by different pollinator groups, local floral neighborhood composition, and flowering phenology affect the total amount and proportion of heterospecific pollen received. Finally, we tested whether variation in heterospecific pollen receipt translated into lower seed production. RESULTS Heterospecific pollen was ubiquitous on O. fruticosa stigmas, but the amount received was highly variable and unrelated to conspecific pollen receipt. Heterospecific pollen receipt depended on pollinator type, the proportion of nearby conspecific flowers, and flowering date. Significant interactions revealed that the effects of pollinator type and neighborhood were not independent, further contributing to variation in heterospecific pollen. Naturally occurring levels of heterospecific pollen were sufficient to negatively impact seed set, but large amounts of conspecific pollen counteracted this detrimental effect. CONCLUSIONS Although selection could act on floral traits that attract quality pollinators and promote synchronous flowering in O. fruticosa, the risk of heterospecific pollen is equally dependent on local floral context. This work highlights how extrinsic and intrinsic factors contribute to intraspecific variation in heterospecific pollen receipt in wild plants, with significant fitness consequences.
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Affiliation(s)
- Gerard X. Smith
- Department of BiologyTemple University1900 N. 12 StreetPhiladelphiaPA19122USA
| | - Mark T. Swartz
- The Pennsylvania Department of Military and Veterans AffairsFort Indiantown Gap National Guard Training CenterAnnvillePA17003USA
| | - Rachel B. Spigler
- Department of BiologyTemple University1900 N. 12 StreetPhiladelphiaPA19122USA
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4
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Unraveling the ecological and evolutionary impacts of a plant invader on the pollination of a native plant. Biol Invasions 2021. [DOI: 10.1007/s10530-021-02457-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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5
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A half-day flowering pattern helps plants sharing pollinators in an oceanic island community. JOURNAL OF TROPICAL ECOLOGY 2021. [DOI: 10.1017/s0266467421000055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractThe temporal pattern of flower opening and closure is a feature of the biology of many plant species, particularly those inhabiting oceanic islands where flowering generally lasts for only a few hours per day. Additionally, flower visitors often seek different floral sources on a timely basis, thus the relative timing of interactions is central to their status in pollination competition, or in the facilitation of pollination among co-flowering plants sharing pollinators. However, few studies have examined the impacts of daily temporal variation in flowering patterns on the pollinator network and competition on a community scale. In order to examine whether the daily pattern of flower opening and closure can impose temporal dynamics on interspecific interactions within a single day, plant–pollinator interaction networks (AM subweb and PM subweb) were quantified, and the relevant interactions between the two subwebs were compared using the Bray–Curtis dissimilarity of visitation frequencies in an oceanic island community (Paracel Islands, South China Sea). The role of species within networks and its variation between two subwebs were assessed by calculating the species-level specialization and species strength of each plant and pollinator species. The quantitative plant–pollinator interaction dissimilarity between morning and afternoon subsets was 0.69, and this value dropped to 0.58 when considering plant species flowering throughout the day. In our study, this dissimilarity between the two subwebs might be explained by the morning peak activity rather than a preference for morning flowers. No significant differences were detected in the species-level specialization and species strength of plants flowering all day from morning to afternoon at the community level. The flower visitation rates of native honeybee Apis cerana were not significantly different between morning and afternoon for most of the whole-day flowering plants. However, plant species only flowering either in the morning or the afternoon differed in the rate of visitation by A. cerana. The analyses of variation in the visitation rates of pollinators shared by plants within a single day in the studied community suggest that daily structuring at a community level and half-day staggered flowering during the morning or afternoon might reduce competitive interactions in oceanic insular habitats.
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6
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Competition and pollen wars: simulations reveal the dynamics of competition mediated through heterospecific pollen transfer by non-flower constant insects. THEOR ECOL-NETH 2020. [DOI: 10.1007/s12080-020-00490-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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7
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Ashman TL, Alonso C, Parra-Tabla V, Arceo-Gómez G. Pollen on stigmas as proxies of pollinator competition and facilitation: complexities, caveats and future directions. ANNALS OF BOTANY 2020; 125:1003-1012. [PMID: 31985008 PMCID: PMC7262468 DOI: 10.1093/aob/mcaa012] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 01/10/2020] [Accepted: 01/23/2020] [Indexed: 05/22/2023]
Abstract
BACKGROUND Pollen transfer via animals is necessary for reproduction by ~80 % of flowering plants, and most of these plants live in multispecies communities where they can share pollinators. While diffuse plant-pollinator interactions are increasingly recognized as the rule rather than the exception, their fitness consequences cannot be deduced from flower visitation alone, so other proxies, functionally closer to seed production and amenable for use in a broad variety of diverse communities, are necessary. SCOPE We conceptually summarize how the study of pollen on stigmas of spent flowers can reflect key drivers and functional aspects of the plant-pollinator interaction (e.g. competition, facilitation or commensalism). We critically evaluate how variable visitation rates and other factors (pollinator pool and floral avoidance) can give rise to different relationships between heterospecific pollen and (1) conspecific pollen on the stigma and (2) conspecific tubes/grain in the style, revealing the complexity of potential interpretations. We advise on best practices for using these proxies, noting the assumptions and caveats involved in their use, and explicate what additional data are required to verify interpretation of given patterns. CONCLUSIONS We conclude that characterizing pollen on stigmas of spent flowers provides an attainable indirect measure of pollination interactions, but given the complex processes of pollen transfer that generate patterns of conspecific-heterospecific pollen on stigmas these cannot alone determine whether competition or facilitation are the underlying drivers. Thus, functional tests are also needed to validate these hypotheses.
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Affiliation(s)
- Tia-Lynn Ashman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
- For correspondence. E-mail
| | - Conchita Alonso
- Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas (EBD-CSIC), Sevilla, Spain
| | - Victor Parra-Tabla
- Department of Tropical Ecology, University of Yucatan, Mérida, Yucatán, México
| | - Gerardo Arceo-Gómez
- Department of Biological Sciences, East Tennessee State University, Johnson City, TN, USA
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Daniels JD, Arceo-Gómez G. Effects of invasive Cirsium arvense on pollination in a southern Appalachian floral community vary with spatial scale and floral symmetry. Biol Invasions 2019. [DOI: 10.1007/s10530-019-02130-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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9
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Moreira-Hernández JI, Muchhala N. Importance of Pollinator-Mediated Interspecific Pollen Transfer for Angiosperm Evolution. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2019. [DOI: 10.1146/annurev-ecolsys-110218-024804] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Understanding how pollen moves between species is critical to understanding speciation, diversification, and evolution of flowering plants. For co-flowering species that share pollinators, competition through interspecific pollen transfer (IPT) can profoundly impact floral evolution, decreasing female fitness via heterospecific pollen deposition on stigmas and male fitness via pollen misplacement during visits to heterospecific flowers. The pollination literature demonstrates that such reproductive interference frequently selects for reproductive character displacement in floral traits linked to pollinator attraction, pollen placement, and mating systems and has also revealed that IPT between given pairs of species is typically asymmetric. More recent work is starting to elucidate its importance to the speciation process, clarifying the link between IPT and current and historical patterns of hybridization, the evolution of phenotypic novelty through adaptive introgression, and the rise of reproductive isolation. Our review aims to stimulate further research on IPT as a ubiquitous mechanism that plays a central role in angiosperm diversification.
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Affiliation(s)
- Juan Isaac Moreira-Hernández
- Department of Biology and Whitney R. Harris World Ecology Center, University of Missouri–St. Louis, St. Louis, Missouri 63121, USA;,
| | - Nathan Muchhala
- Department of Biology and Whitney R. Harris World Ecology Center, University of Missouri–St. Louis, St. Louis, Missouri 63121, USA;,
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10
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Wang LL, Zhang ZQ, Yang YP, Duan YW. The coexistence of hermaphroditic and dioecious plants is associated with polyploidy and gender dimorphism in Dasiphora fruticosa. PLANT DIVERSITY 2019; 41:323-329. [PMID: 31934677 PMCID: PMC6951273 DOI: 10.1016/j.pld.2019.06.002] [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: 03/01/2019] [Revised: 06/06/2019] [Accepted: 06/10/2019] [Indexed: 06/10/2023]
Abstract
Dasiphora fruticosa comprises male, female and hermaphrodite plants, which are distributed sympatrically in some populations on the Qinghai-Tibet Plateau. To explore what governs the coexistence of these three sexual phenotypes, we investigated the DNA contents, pollen and ovule production, pollen deposition, and performed hand-pollination in both hermaphroditic and dioecious individuals of D. fruticosa. Flow cytometry confirmed that the DNA content of males and females were almost twice as much as that of the hermaphrodites. Male and female flowers produced more pollen grains and ovules than hermaphroditic flowers. Hand-pollinated treatments showed that unisexual flowers were sterile in one sexual function and bisexual flowers were fertile for both functions, but no sterile seeds were produced between unisexual and bisexual flowers. Our findings imply that polyploidy is related to gender dimorphism, and both are likely to play a strong role in the coexistence of two cryptic biological species of D. fruticosa (low ploidy hermaphroditic species and high ploidy dioecious species) in the Qinghai-Tibet Plateau.
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Affiliation(s)
- Lin-Lin Wang
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Germplasm Bank of Wild Species, Institute of Tibetan Plateau Research at Kunming, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, 650201, China
- University of the Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhi-Qiang Zhang
- Laboratory of Ecology and Evolutionary Biology, Yunnan University, Kunming, Yunnan, 650091, China
| | - Yong-Ping Yang
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Germplasm Bank of Wild Species, Institute of Tibetan Plateau Research at Kunming, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, 650201, China
| | - Yuan-Wen Duan
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Germplasm Bank of Wild Species, Institute of Tibetan Plateau Research at Kunming, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, 650201, China
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11
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Fang Q, Gao J, Armbruster WS, Huang S. Multi‐year stigmatic pollen‐load sampling reveals temporal stability in interspecific pollination of flowers in a subalpine meadow. OIKOS 2019. [DOI: 10.1111/oik.06447] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Qiang Fang
- Inst. of Evolution and Ecology, School of Life Sciences, Central China Normal Univ CN‐430079 Wuhan PR China
- College of Agriculture, Henan Univ. of Science and Technology Luoyang PR China
| | - Jie Gao
- Inst. of Horticulture, Henan Academy of Agricultural Science Zhengzhou PR China
| | - W. Scott Armbruster
- School of Biological Sciences, Univ. of Portsmouth Portsmouth UK
- Inst. of Arctic Biology, Univ. of Alaska Fairbanks AL USA
| | - Shuang‐Quan Huang
- Inst. of Evolution and Ecology, School of Life Sciences, Central China Normal Univ CN‐430079 Wuhan PR China
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12
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Smith C, Weinman L, Gibbs J, Winfree R. Specialist foragers in forest bee communities are small, social or emerge early. J Anim Ecol 2019; 88:1158-1167. [PMID: 31063228 DOI: 10.1111/1365-2656.13003] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 04/02/2019] [Indexed: 12/01/2022]
Abstract
Individual pollinators that specialize on one plant species within a foraging bout transfer more conspecific and less heterospecific pollen, positively affecting plant reproduction. However, we know much less about pollinator specialization at the scale of a foraging bout compared to specialization by pollinator species. In this study, we measured the diversity of pollen carried by individual bees foraging in forest plant communities in the mid-Atlantic United States. We found that individuals frequently carried low-diversity pollen loads, suggesting that specialization at the scale of the foraging bout is common. Individuals of solitary bee species carried higher diversity pollen loads than did individuals of social bee species; the latter have been better studied with respect to foraging bout specialization, but account for a small minority of the world's bee species. Bee body size was positively correlated with pollen load diversity, and individuals of polylectic (but not oligolectic) species carried increasingly diverse pollen loads as the season progressed, likely reflecting an increase in the diversity of flowers in bloom. Furthermore, the seasonal increase in pollen load diversity was stronger for bees visiting trees and shrubs than for bees visiting herbaceous plants. Overall, our results showed that both plant and pollinator species' traits as well as community-level patterns of flowering phenology are likely to be important determinants of individual-level interactions in plant-pollinator communities.
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Affiliation(s)
- Colleen Smith
- Graduate Program in Ecology & Evolution, Rutgers University, New Brunswick, New Jersey.,Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, New Jersey
| | - Lucia Weinman
- Graduate Program in Ecology & Evolution, Rutgers University, New Brunswick, New Jersey.,Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, New Jersey
| | - Jason Gibbs
- Department of Entomology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Rachael Winfree
- Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, New Jersey
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13
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Konzmann S, Koethe S, Lunau K. Pollen grain morphology is not exclusively responsible for pollen collectability in bumble bees. Sci Rep 2019; 9:4705. [PMID: 30886330 PMCID: PMC6423004 DOI: 10.1038/s41598-019-41262-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Accepted: 03/05/2019] [Indexed: 11/25/2022] Open
Abstract
Bee-pollinated plants face a dilemma in that bees both passively transport pollen grains among conspecific flowers and actively collect pollen to feed their larvae. Therefore, mechanisms that reduce pollen collection by bees have evolved in melittophilous plants. Malvaceae pollen is uncollectable for corbiculate bees which has previously been ascribed to pollen size, spines, and pollenkitt. We analysed the influence of pollen grain properties (diameter, spine length, spine density) on the collectability of echinate (spiny) pollen by bumble bees (Bombus terrestris). Workers individually foraging on one of eight plant species from six families performed significantly less pollen foraging on plants which have large, echinate pollen grains. Nevertheless, neither pollen grain size, spine length, nor spine density prove to be an absolute disqualifier for collectability. While pollen foragers did not shift to nectar collection but seized visiting flowers with uncollectable pollen, nectar foragers performed regular foraging bouts on these plants. Pollen that is uncollectable for corbiculate bees limits pollen depletion by generalist bumble bees and probably also honey bees while maintaining them as pollinators, which is an effective solution to the pollen dilemma. As previous assumptions about the impact of pollen morphology on its collectability are disproved, potentially determining factors are discussed.
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Affiliation(s)
- Sabine Konzmann
- Institute of Sensory Ecology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
| | - Sebastian Koethe
- Institute of Sensory Ecology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Klaus Lunau
- Institute of Sensory Ecology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
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14
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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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15
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Goodell K, Parker IM. Invasion of a dominant floral resource: effects on the floral community and pollination of native plants. Ecology 2018; 98:57-69. [PMID: 28052387 DOI: 10.1002/ecy.1639] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 08/18/2016] [Accepted: 10/17/2016] [Indexed: 11/11/2022]
Abstract
Through competition for pollinators, invasive plants may suppress native flora. Community-level studies provide an integrative assessment of invasion impacts and insights into factors that influence the vulnerability of different native species. We investigated effects of the nonnative herb Lythrum salicaria on pollination of native species in 14 fens of the eastern United States. We compared visitors per flower for 122 native plant species in invaded and uninvaded fens and incorporated a landscape-scale experiment, removing L. salicaria flowers from three of the invaded fens. Total flower densities were more than three times higher in invaded than uninvaded or removal sites when L. salicaria was blooming. Despite an increase in number of visitors with number of flowers per area, visitors per native flower declined with increasing numbers of flowers. Therefore, L. salicaria invasion depressed visitation to native flowers. In removal sites, visitation to native flowers was similar to uninvaded sites, confirming the observational results and also suggesting that invasion had not generated a persistent build-up of visitor populations. To study species-level impacts, we examined effects of invasion on visitors per flower for the 36 plant species flowering in both invaded and uninvaded fens. On average, the effect of invasion represented about a 20% reduction in visits per flower. We measured the influence of plant traits on vulnerability to L. salicaria invasion using meta-analysis. Bilaterally symmetrical flowers experienced stronger impacts on visitation, and similarity in flower color to L. salicaria weakly intensified competition with the invader for visitors. Finally, we assessed the reproductive consequences of competition with the invader in a dominant flowering shrub, Dasiphora fruticosa. Despite the negative effect of invasion on pollinator visitation in this species, pollen limitation of seed production was not stronger in invaded than in uninvaded sites, suggesting little impact of competition for pollinators on its population demography. Negative effects on pollination of native plants by this copiously flowering invader appeared to be mediated by increases in total flower density that were not matched by increases in pollinator density. The strength of impact was modulated across native species by their floral traits and reproductive ecology.
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Affiliation(s)
- Karen Goodell
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Newark, Ohio, 43055, USA
| | - Ingrid M Parker
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, California, 95064, USA
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16
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Fang Q, Huang SQ. A paradoxical mismatch between interspecific pollinator moves and heterospecific pollen receipt in a natural community. Ecology 2018; 97:1970-1978. [PMID: 27859194 DOI: 10.1002/ecy.1433] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 02/08/2016] [Accepted: 03/06/2016] [Indexed: 11/08/2022]
Abstract
Pollinators visiting multiple plant species may cause heterospecific pollen transfer (HPT). To test a null model that more pollinator interspecific moves result in higher HPT among interacting species, we quantified the comparative magnitudes of the two networks involving 14 co-flowering species in an alpine meadow in the eastern Himalaya, southwest China. Interspecific moves accounted for 4% of the total visits,whereas heterospecific pollen constituted 22% of the total stigmatic pollen loads. On average, plant species received interspecific moves and HPT from 6.9 and 9.7 other species, respectively. Although the two networks were largely concordant, 21.6% of interspecific move links were not correspondingly linked by HPT, and 44.1% of heterospecific pollen transfer links were not linked by moves. Plant species with more outgoing pollinator moves tended to disperse more of their own pollen to others, as expected. Surprisingly, our data reveal that plant species which received more pollinator moves from other species tended to receive less HP, implying that only species with low acceptance of HP were likely to permit frequent pollinator moves. These new findings unveil a paradoxical relation between pollinator interspecific moves and HP receipt, suggesting an adaptive strategy of co-flowering species that reduces deleterious effects of HPT.
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Affiliation(s)
- Qiang Fang
- College of Agriculture, Henan University of Science and Technology, Luoyang, 471003, China.,Institute of Evolution and Ecology, School of Life Sciences, Central China Normal University, Wuhan, 430079, China
| | - Shuang-Quan Huang
- Institute of Evolution and Ecology, School of Life Sciences, Central China Normal University, Wuhan, 430079, China
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17
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Ison JL, Prescott LJ, Nordstrom SW, Waananen A, Wagenius S. Pollinator-mediated mechanisms for increased reproductive success in early flowering plants. OIKOS 2018. [DOI: 10.1111/oik.04882] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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18
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Randle AM, Spigler RB, Kalisz S. Shifts to earlier selfing in sympatry may reduce costs of pollinator sharing. Evolution 2018; 72:1587-1599. [PMID: 29917223 DOI: 10.1111/evo.13522] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2017] [Revised: 05/28/2018] [Accepted: 06/07/2018] [Indexed: 01/02/2023]
Abstract
Coexisting plant congeners often experience strong competition for resources. Competition for pollinators can result in direct fitness costs via reduced seed set or indirect costs via heterospecific pollen transfer (HPT), causing subsequent gamete loss and unfit hybrid offspring production. Autonomous selfing may alleviate these costs, but to preempt HPT, selfing should occur early, before opportunities for HPT occur (i.e., "preemptive selfing hypothesis"). We evaluated conditions for this hypothesis in Collinsia sister species, C. linearis and C. rattanii. In field studies, we found virtually identical flowering times and pollinator sharing between congeners in sympatric populations. Compared to allopatric populations, sympatric C. linearis populations enjoyed higher pollinator visitation rates, whereas visitation to C. rattanii did not differ in sympatry. Importantly, the risk of HPT to each species in sympatry was strongly asymmetrical; interspecies visits comprised 40% of all flower-to-flower visits involving C. rattanii compared to just 4% involving C. linearis. Additionally, our greenhouse experiment demonstrated a strong cost of hybridization when C. rattanii was the pollen donor. Together, these results suggest that C. rattanii pays the greatest cost of pollinator sharing. Matching predictions of the preemptive selfing hypothesis, C. rattanii exhibit significantly earlier selfing in sympatric relative to allopatric populations.
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Affiliation(s)
- April M Randle
- Department of Environmental Science, University of San Francisco, San Francisco, California, 94117
| | - Rachel B Spigler
- Department of Biology, Temple University, Philadelphia, Pennsylvania, 19122
| | - Susan Kalisz
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, Knoxville, Tennessee, 37919
- Carnegie Museum of Natural History, Pittsburgh, Pennsylvania, 15213
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19
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Benadi G, Gegear RJ. Adaptive Foraging of Pollinators Can Promote Pollination of a Rare Plant Species. Am Nat 2018; 192:E81-E92. [PMID: 30016159 DOI: 10.1086/697582] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Most pollinators have the foraging flexibility to visit a wide variety of plant species. Yet few studies of pollinator-mediated processes in plants have considered the effects of variation in individual foraging patterns on plant reproductive success. In this study, we use an individual-based model of pollinator foraging economics to predict how visitation rates and pollination success of two coflowering plant species change with their frequency (relative abundance). Whereas previous studies suggested that adaptive foraging of pollinators always favors pollination of abundant plant species (positive frequency dependence), here we show that under certain conditions the per capita pollination success of a rare plant species can exceed that of a more abundant species. Specifically, when the overall flower density is sufficiently high and pollinators' perception ranges are sufficiently large, animals with limited memory of previously encountered rewards forage in a way that favors pollination of the rarer plant species. Moreover, even with perfectly informed foragers, a rare plant species benefits more from offering a higher floral reward than a more abundant species. Our results show that adaptive foraging of individual pollinators can have important implications for plant community dynamics and the persistence of rare plant species.
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20
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Safe sites of pollen placement: a conflict of interest between plants and bees? Oecologia 2017; 186:163-171. [DOI: 10.1007/s00442-017-3999-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 11/03/2017] [Indexed: 10/18/2022]
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21
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Low interspecific pollen transfer between invasive aquatic Ludwigia grandiflora and native co-flowering plants. Biol Invasions 2017. [DOI: 10.1007/s10530-017-1494-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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22
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Sánchez AM, Rodríguez M, Albert MJ, Escudero A. Effects of season and population size on pollination and reproductive output in a Mediterranean shrub. PLANT BIOLOGY (STUTTGART, GERMANY) 2017; 19:428-437. [PMID: 28135028 DOI: 10.1111/plb.12550] [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: 02/24/2016] [Accepted: 01/25/2017] [Indexed: 06/06/2023]
Abstract
Pollinator guilds may change throughout extended flowering periods, affecting plant reproductive output, especially in seasonal climates. We hypothesised a seasonal shift in pollinator guild and an autumn reduction in pollinator abundance, especially in small and sparse populations. We recorded pollinator identity, abundance and behaviour in relation to flower density from plant to population throughout the extended flowering of Ononis tridentata. We evaluated female reproductive output by recording pollination success and pre-dispersal seed predation in eight populations of contrasting size and density. Offspring quality was also characterised through seed weight and germination. A diverse guild of insects visited O. tridentata in spring, while only Apis mellifera was observed in autumn. Visitation frequency did not vary seasonally, but the number of flowers per foraging bout was lower, and seeds were heavier and had a higher germination rate in autumn. Plant and neighbourhood flowering display were not related to pollinator visitation frequency or behaviour. However, the rate of fertilised ovules, seed set and autumn flowering display size were positively related to population density. The maintenance of pollination in autumn enhances the reproductive performance of O. tridentata due to higher quality of autumn seed, and to a large reduction in seed predator pressure. We also suggest that observed changes in pollinator behaviour could be one of the processes behind seasonal variation in seed performance, since geitonogamous crosses were less likely to occur in autumn.
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Affiliation(s)
- A M Sánchez
- Área de Biodiversidad y Conservación, Universidad Rey Juan Carlos, Móstoles, Spain
| | - M Rodríguez
- Área de Biodiversidad y Conservación, Universidad Rey Juan Carlos, Móstoles, Spain
| | - M J Albert
- Área de Biodiversidad y Conservación, Universidad Rey Juan Carlos, Móstoles, Spain
| | - A Escudero
- Área de Biodiversidad y Conservación, Universidad Rey Juan Carlos, Móstoles, Spain
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23
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Stewart AB, Dudash MR. Field evidence of strong differential pollen placement by Old World bat-pollinated plants. ANNALS OF BOTANY 2017; 119:73-79. [PMID: 27864223 PMCID: PMC5218376 DOI: 10.1093/aob/mcw212] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Revised: 08/01/2016] [Accepted: 09/03/2016] [Indexed: 06/01/2023]
Abstract
BACKGROUND AND AIMS Sympatric plant species that share pollinators potentially compete for pollination and risk interspecific pollen transfer, but this competition can be minimized when plant species place pollen on different areas of the pollinator's body. Multiple studies have demonstrated strong differential pollen placement by sympatric plant species under laboratory conditions; however, field evidence collected in natural settings is less common. Furthermore, it is unknown whether precise pollen placement on the pollinator's body remains constant throughout the foraging period, or if such patterns become diffused over time (e.g. due to grooming). To test the prevalence of differential pollen placement in the wild, we examined a community of five night-blooming plant species in southern Thailand that share common bat pollinators. METHODS We mist-netted wild foraging nectar bats and collected pollen samples from four body parts: the crown of the head, face, chest and ventral side of one wing. We also noted the time of pollen collection to assess how pollinator pollen loads change throughout the foraging period. KEY RESULTS Our findings revealed that most of our plant study species placed pollen on precise areas of the bat, consistent with experimental work, and that patterns of differential pollen placement remained constant throughout the night. CONCLUSIONS This study demonstrates how diverse floral morphologies effectively limit interspecific pollen transfer among Old World bat-pollinated plants under natural conditions. Additionally, interspecific pollen transfer is probably minimal throughout the entire foraging period, since patterns of pollen on the bats' bodies were consistent over time.
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Affiliation(s)
- Alyssa B Stewart
- Department of Plant Science, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Michele R Dudash
- Department of Biology, University of Maryland, College Park, MD 20742, USA
- Department of Natural Resource Management, South Dakota State University, Brookings, SD 57007, USA
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24
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Schmid B, Nottebrock H, Esler KJ, Pagel J, Böhning-Gaese K, Schurr FM, Mueller T, Schleuning M. A bird pollinator shows positive frequency dependence and constancy of species choice in natural plant communities. Ecology 2016; 97:3110-3118. [PMID: 27870050 DOI: 10.1002/ecy.1565] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 06/04/2016] [Accepted: 07/21/2016] [Indexed: 11/06/2022]
Abstract
Animal pollinators mediate reproduction of many plant species. Foraging theory suggests that animal pollinators exhibit preferences for common plant species in natural communities (positive frequency-dependent foraging) and temporary single-species specialization (flower constancy) during foraging bouts. Positive frequency dependence may favor common plant species; flower constancy may enhance conspecific pollen transfer particularly in rare plant species. Previous experimental studies suggest that avian pollinators are unlikely to exhibit these behaviors. We studied foraging behavior of Cape Sugarbirds (Promerops cafer), the main avian pollinator of many Protea species, using focal-plant and focal-bird sampling, assisted by high-resolution maps of the spatiotemporal distribution of Protea individuals and their flowering status. We found that Sugarbird's visitation preference increased with species' relative floral abundance, and that individual Sugarbirds tended to visit single species in sequence. Flower constancy during foraging bouts was significantly higher than expected from random plant-animal encounters at the scale of pollinator movements. Positive frequency dependence may favor the reproduction of abundant plant species while flower constancy may be particularly important for rare plant species. This first simultaneous study of both behaviors in a natural plant-pollinator system shows that bird pollinators exhibit both types of behavior and, in this way, possibly influence plant community structure.
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Affiliation(s)
- B Schmid
- Senckenberg Biodiversity and Climate Research Centre (BiK-F), Senckenberganlage 25, Frankfurt am Main, 60325, Germany.,Department of Conservation Biology and Entomology and Centre for Invasion Biology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.,Swiss Ornithological Institute, 6204, Sempach, Switzerland
| | - H Nottebrock
- Department of Conservation Biology and Entomology and Centre for Invasion Biology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.,Institute of Landscape and Plant Ecology, University of Hohenheim, August-von-Hartmann-Street 3, Stuttgart, 70599, Germany.,Institut des Sciences de l'Evolution, UMR 5554, Université Montpellier 2, Place Eugène Bataillon, Montpellier Cedex 05, F-34095, France
| | - K J Esler
- Department of Conservation Biology and Entomology and Centre for Invasion Biology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - J Pagel
- Institute of Landscape and Plant Ecology, University of Hohenheim, August-von-Hartmann-Street 3, Stuttgart, 70599, Germany.,Institut des Sciences de l'Evolution, UMR 5554, Université Montpellier 2, Place Eugène Bataillon, Montpellier Cedex 05, F-34095, France
| | - K Böhning-Gaese
- Senckenberg Biodiversity and Climate Research Centre (BiK-F), Senckenberganlage 25, Frankfurt am Main, 60325, Germany.,Department of Biological Sciences, Johann Wolfgang Goethe-University, Max-von-Laue-Straße 9, Frankfurt am Main, 60438, Germany
| | - F M Schurr
- Institute of Landscape and Plant Ecology, University of Hohenheim, August-von-Hartmann-Street 3, Stuttgart, 70599, Germany.,Institut des Sciences de l'Evolution, UMR 5554, Université Montpellier 2, Place Eugène Bataillon, Montpellier Cedex 05, F-34095, France
| | - T Mueller
- Senckenberg Biodiversity and Climate Research Centre (BiK-F), Senckenberganlage 25, Frankfurt am Main, 60325, Germany.,Department of Biological Sciences, Johann Wolfgang Goethe-University, Max-von-Laue-Straße 9, Frankfurt am Main, 60438, Germany
| | - M Schleuning
- Senckenberg Biodiversity and Climate Research Centre (BiK-F), Senckenberganlage 25, Frankfurt am Main, 60325, Germany
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25
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Stewart AB, Dudash MR. Flower‐visiting bat species contribute unequally toward agricultural pollination ecosystem services in southern Thailand. Biotropica 2016. [DOI: 10.1111/btp.12401] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Alyssa B. Stewart
- Department of Biology University of Maryland College Park MD 20742 USA
- Department of Plant Science Faculty of Science Mahidol University Bangkok 10400 Thailand
| | - Michele R. Dudash
- Department of Biology University of Maryland College Park MD 20742 USA
- Department of Natural Resource Management South Dakota State University Brookings SD 57007 USA
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26
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Tong ZY, Huang SQ. Pre- and post-pollination interaction between six co-flowering Pedicularis species via heterospecific pollen transfer. THE NEW PHYTOLOGIST 2016; 211:1452-1461. [PMID: 27174497 DOI: 10.1111/nph.14005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 04/06/2016] [Indexed: 06/05/2023]
Abstract
It remains unclear how related co-flowering species with shared pollinators minimize reproductive interference, given that the degree of interspecific pollen flow and its consequences are little known in natural communities. Differences in pollen size in six Pedicularis species with different style lengths permit us to measure heterospecific pollen transfer (HPT) between species pairs in sympatry. The role of pollen-pistil interactions in mitigating the effects of HPT was examined. Field observations over 2 yr showed that bumblebee pollinators visiting one species rarely moved to another. Heterospecific pollen (HP) comprised < 10% of total stigmatic pollen loads for each species over 2 yr, and was not related to conspecific pollen deposition. Species with longer styles generally received more HP per stigma. The pollen tube study showed that pollen from short-styled species could not grow the full length of the style of long-styled species. Pollen from long-styled species could grow through the short style of P. densispica, but P. densispica rarely received HP in nature. Flower constancy is a key pre-pollination barrier to HPT between co-flowering Pedicularis species. Post-pollination pollen-pistil interactions may further mitigate the effects of HPT because HP transferred to long styles could generally be effectively filtered.
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Affiliation(s)
- Ze-Yu Tong
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Shuang-Quan Huang
- Institute of Evolution and Ecology, School of Life Sciences, Central China Normal University, Wuhan, 430079, China
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27
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Sorin YB, Mitchell RJ, Trapnell DW, Karron JD. Effects of pollination and postpollination processes on selfing rate in Mimulus ringens. AMERICAN JOURNAL OF BOTANY 2016; 103:1524-1528. [PMID: 27539262 DOI: 10.3732/ajb.1600145] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 06/20/2016] [Indexed: 06/06/2023]
Abstract
PREMISE OF THE STUDY Selfing rates vary widely within and among populations of self-compatible flowering plants. This variation is often attributed to differences in the amount and timing of self and outcross pollen deposition on stigmas, as well as to the influence of postpollination mechanisms that control fertilization success. This study explores the relative importance of pollination and postpollination processes in determining selfing rates in monkeyflower, Mimulus ringens. METHODS We hand-pollinated flowers on 17 unrelated mothers with pollen from one of three experimental treatments intended to replicate field conditions: (1) simultaneous deposition of 50% self pollen and 50% outcross pollen from 5 unrelated donors; (2) self pollen followed 15 min later by application of an equal amount of outcross pollen from five unrelated donors; and (3) outcross pollen from 5 unrelated donors followed 15 min later by application of an equal amount of self pollen. We genotyped 757 progeny at 8 polymorphic microsatellite loci and used paternity exclusion to determine whether each seedling was selfed or outcrossed. KEY RESULTS When self and outcross pollen arrived simultaneously, and when self pollen arrived 15 min prior to outcross pollen, the observed proportions of self and outcross progeny did not deviate from the expected 1:1 ratio. However, when outcross pollen was applied 15 min prior to self pollen, there was a significant excess of outcross progeny. CONCLUSIONS Selfing rate in Mimulus ringens is influenced by small differences in the timing of pollen arrival, but not by nonrandom postpollination sorting.
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Affiliation(s)
- Yuliya B Sorin
- Department of Biological Sciences, P.O. Box 413, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201-0413 USA
| | | | - Dorset W Trapnell
- Department of Plant Biology, 2502 Miller Plant Sciences, University of Georgia, Athens, Georgia 30602-7271
| | - Jeffrey D Karron
- Department of Biological Sciences, P.O. Box 413, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201-0413 USA
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28
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Ogilvie JE, Thomson JD. Site fidelity by bees drives pollination facilitation in sequentially blooming plant species. Ecology 2016; 97:1442-51. [DOI: 10.1890/15-0903.1] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Jane E. Ogilvie
- Department of Ecology and Evolutionary Biology; University of Toronto; 25 Harbord Street Toronto Ontario M5S 3G5 Canada
- The Rocky Mountain Biological Laboratory; Post Office Box 519 Crested Butte Colorado 81224-0519 USA
| | - James D. Thomson
- Department of Ecology and Evolutionary Biology; University of Toronto; 25 Harbord Street Toronto Ontario M5S 3G5 Canada
- The Rocky Mountain Biological Laboratory; Post Office Box 519 Crested Butte Colorado 81224-0519 USA
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29
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Benadi G. Requirements for plant coexistence through pollination niche partitioning. Proc Biol Sci 2016; 282:rspb.2015.0117. [PMID: 26108627 DOI: 10.1098/rspb.2015.0117] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Plant-pollinator interactions are often thought to have been a decisive factor in the diversification of flowering plants, but to be of little or no importance for the maintenance of existing plant diversity. In a recent opinion paper, Pauw (2013 Trends Ecol. Evol. 28, 30-37. (doi:10.1016/j.tree.2012.07.019)) challenged this view by proposing a mechanism of diversity maintenance based on pollination niche partitioning. In this article, I investigate under which conditions the mechanism suggested by Pauw can promote plant coexistence, using a mathematical model of plant and pollinator population dynamics. Numerical simulations show that this mechanism is most effective when the costs of searching for flowers are low, pollinator populations are strongly limited by resources other than pollen and nectar, and plant-pollinator interactions are sufficiently specialized. I review the empirical literature on these three requirements, discuss additional factors that may be important for diversity maintenance through pollination niche partitioning, and provide recommendations on how to detect this coexistence mechanism in natural plant communities.
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Affiliation(s)
- Gita Benadi
- Biometry and Environmental System Analysis, University of Freiburg, Tennenbacherstrasse 4, 79106 Freiburg im Breisgau, Germany
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30
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Tur C, Sáez A, Traveset A, Aizen MA. Evaluating the effects of pollinator-mediated interactions using pollen transfer networks: evidence of widespread facilitation in south Andean plant communities. Ecol Lett 2016; 19:576-86. [DOI: 10.1111/ele.12594] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Revised: 11/06/2015] [Accepted: 02/04/2016] [Indexed: 11/26/2022]
Affiliation(s)
- C. Tur
- Cristina Tur. IMEDEA- Institut Mediterrani d'Estudis Avançats (CSIC-UIB); Miquel Marqués 21 07190 Esporles Illes Balears Spain
| | - A. Sáez
- Agustín Sáez. Laboratorio ECOTONO; INIBIOMA; UNComa. Pasaje Gutiérrez 1125 Bariloche Río Negro Argentina
| | - A. Traveset
- Anna Traveset. IMEDEA- Institut Mediterrani d'Estudis Avançats (CSIC-UIB); Miquel Marqués 21 07190 Esporles Illes Balears Spain
| | - M. A. Aizen
- Marcelo A. Aizen. Laboratorio ECOTONO; INIBIOMA; UNComa. Pasaje Gutiérrez 1125 Bariloche Río Negro Argentina
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31
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Stewart AB, Dudash MR. Differential pollen placement on an Old World nectar bat increases pollination efficiency. ANNALS OF BOTANY 2016; 117:145-52. [PMID: 26482654 PMCID: PMC4701156 DOI: 10.1093/aob/mcv163] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Accepted: 09/04/2015] [Indexed: 05/05/2023]
Abstract
BACKGROUND AND AIMS Plant species that share pollinators are potentially subject to non-adaptive interspecific pollen transfer, resulting in reduced reproductive success. Mechanisms that increase pollination efficiency between conspecific individuals are therefore highly beneficial. Many nocturnally flowering plant species in Thailand are pollinated by the nectar bat Eonycteris spelaea (Pteropodidae). This study tested the hypothesis that plant species within a community reduce interspecific pollen movement by placing pollen on different areas of the bat's body. METHODS Using flight cage trials, pollen transfer by E. spelaea was compared between conspecific versus heterospecific flowers across four bat-pollinated plant genera. Pollen from four locations on the bat's body was also quantified to determine if pollen placement varies by plant species. KEY RESULTS It was found that E. spelaea transfers significantly more pollen between conspecific than heterospecific flowers, and that diverse floral designs produce significantly different patterns of pollen deposition on E. spelaea. CONCLUSIONS In the Old World tropics, differential pollen placement is a mechanism that reduces competition among bat-pollinated plant species sharing a common pollinator.
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Affiliation(s)
- Alyssa B Stewart
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Michele R Dudash
- Department of Biology, University of Maryland, College Park, MD 20742, USA
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32
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Muir JL, Vamosi JC. Invasive Scotch broom (Cytisus scoparius, Fabaceae) and the pollination success of three Garry oak-associated plant species. Biol Invasions 2015. [DOI: 10.1007/s10530-015-0886-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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33
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Beans CM, Roach DA. An invasive plant alters pollinator-mediated phenotypic selection on a native congener. AMERICAN JOURNAL OF BOTANY 2015; 102:50-57. [PMID: 25587147 DOI: 10.3732/ajb.1400385] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
UNLABELLED • PREMISE OF STUDY Recent studies suggest that invasive plants compete reproductively with native plants by reducing the quantity or quality of pollinator visits. Although these studies have revealed ecological consequences of pollinator-mediated competition between invasive and native plants, the evolutionary outcomes of these interactions remain largely unexplored.• METHODS We studied the ecological and evolutionary impact of pollinator-mediated competition with an invasive jewelweed, Impatiens glandulifera, on a co-occurring native congener, I. capensis. Using a pollinator choice experiment, a hand pollination experiment, and a selection analysis, we addressed the following questions: (1) Do native pollinators show preference for the invasive or native jewelweed, and do they move between the two species? (2) Does invasive jewelweed pollen inhibit seed production in the native plant? (3) Does the invasive jewelweed alter phenotypic selection on the native plant's floral traits?• KEY RESULTS The pollinator choice experiment showed that pollinators strongly preferred the invasive jewelweed. The hand pollination experiment demonstrated that invasive pollen inhibited seed production in the native plant. The selection analysis showed that the presence of the invasive jewelweed altered phenotypic selection on corolla height in the native plant.• CONCLUSIONS Invasive plants have the potential to alter phenotypic selection on floral traits in native plant populations. If native plants can evolve in response to this altered selection pressure, the evolution of floral traits may play an important role in permitting long-term coexistence of native and invasive plants.
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Affiliation(s)
- Carolyn M Beans
- Department of Biology, University of Virginia, P.O. Box 400328, Charlottesville, Virginia 22904-4328, USA
| | - Deborah A Roach
- Department of Biology, University of Virginia, P.O. Box 400328, Charlottesville, Virginia 22904-4328, USA
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34
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High-altitude multi-taskers: bumble bee food plant use broadens along an altitudinal productivity gradient. Oecologia 2014; 176:1033-45. [PMID: 25199658 DOI: 10.1007/s00442-014-3066-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 08/22/2014] [Indexed: 12/30/2022]
Abstract
We use an extensive historical data set on bumble bee host choice collected almost 50 years ago by L. W. Macior (Melanderia 15:1-59, 1974) to examine how resource partitioning by bumble bees varies over a 2,700-m altitudinal gradient at four hierarchical scales: individual, colony, species and community. Bumble bee behavior, resource overlap between castes, and plant-bumble bee networks change with altitude in accordance with tightening temporal constraints on flowering and colony growth in alpine habitats. Individual bees were more likely to collect pollen from multiple sources at high altitude. Between-caste foraging niche overlap increased with altitude. Similarly, alpine forager networks were more highly nested than either subalpine or montane networks due to increased asymmetric specialization. However, interspecific resource partitioning showed a more complex spatial pattern with low niche overlap at intermediate altitude (subalpine) compared to montane (disturbed) and alpine (unproductive) sites. Results suggest that spatial variation in interspecific resource partitioning is driven by a shift in the behavior of long-tongued bumble bees. Long-tongued bumble bees specialized in the subalpine but generalized in montane and alpine zones. Our reanalysis of Macior's data shows that bumble bee behavior varies substantially with altitude influencing plant-bumble bee interaction networks. Results imply that pollination services to alpine host plants will change dramatically as subalpine species with unique foraging strategies move upward under global warming.
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Johnson CM, Pauw A. Adaptation for rodent pollination in Leucospermum arenarium (Proteaceae) despite rapid pollen loss during grooming. ANNALS OF BOTANY 2014; 113:931-938. [PMID: 24607723 PMCID: PMC3997634 DOI: 10.1093/aob/mcu015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 01/27/2014] [Indexed: 06/03/2023]
Abstract
BACKGROUND AND AIMS Plants are adapted for rodent pollination in diverse and intricate ways. This study explores an extraordinary example of these adaptations in the pincushion Leucospermum arenarium (Proteaceae) from South Africa. METHODS Live trapping and differential exclusion experiments were used to test the role of rodents versus birds and insects as pollinators. To explore the adaptive significance of geoflory, inflorescences were raised above ground level and seed production was compared. Captive rodents and flowers with artificial stigmas were used to test the effect of grooming on the rate of pollen loss. Microscopy, nectar composition analysis and manipulative experiments were used to investigate the bizarre nectar production and transport system. KEY RESULTS Differential exclusion of rodents, birds and insects demonstrated the importance of rodents in promoting seed production. Live trapping revealed that hairy-footed gerbils, Gerbillurus paeba, and striped field mice, Rhabdomys pumilio, both carried L. arenarium pollen on their forehead and rostrum, but much larger quantities ended up in faeces as a result of grooming. Terrarium experiments showed that grooming exponentially diminished the pollen loads that they carried. The nectar of L. arenarium was found to be unusually viscous and to be presented in a novel location on the petal tips, where rodents could access it without destroying the flowers. Nectar was produced inside the perianth, but was translocated to the petal tips via capillary ducts. In common with many other rodent-pollinated plants, the flowers are presented at ground level, but when raised to higher positions seed production was not reduced, indicating that selection through female function does not drive the evolution of geoflory. CONCLUSIONS Despite the apparent cost of pollen lost to grooming, L. arenarium has evolved remarkable adaptations for rodent pollination and provides the first case of this pollination system in the genus.
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Falik O, Hoffmann I, Novoplansky A. Say it with flowers: flowering acceleration by root communication. PLANT SIGNALING & BEHAVIOR 2014; 9:e28258. [PMID: 24598343 PMCID: PMC4091325 DOI: 10.4161/psb.28258] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Accepted: 02/17/2014] [Indexed: 05/26/2023]
Abstract
The timing of reproduction is a critical determinant of fitness, especially in organisms inhabiting seasonal environments. Increasing evidence suggests that inter-plant communication plays important roles in plant functioning. Here, we tested the hypothesis that flowering coordination can involve communication between neighboring plants. We show that soil leachates from Brassica rapa plants growing under long-day conditions accelerated flowering and decreased allocation to vegetative organs in target plants growing under non-inductive short-day conditions. The results suggest that besides endogenous signaling and external abiotic cues, flowering timing may involve inter-plant communication, mediated by root exudates. The study of flowering communication is expected to illuminate neglected aspects of plant reproductive interactions and to provide novel opportunities for controlling the timing of plant reproduction in agricultural settings.
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Affiliation(s)
- Omer Falik
- Mitrani Department of Desert Ecology; Blaustein Institutes for Desert Research; Ben-Gurion University of the Negev; Midreshet Ben-Gurion, 84990, Israel
| | - Ishay Hoffmann
- Mitrani Department of Desert Ecology; Blaustein Institutes for Desert Research; Ben-Gurion University of the Negev; Midreshet Ben-Gurion, 84990, Israel
| | - Ariel Novoplansky
- Mitrani Department of Desert Ecology; Blaustein Institutes for Desert Research; Ben-Gurion University of the Negev; Midreshet Ben-Gurion, 84990, Israel
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Arceo-Gómez G, Ashman TL. Coflowering Community Context Influences Female Fitness and Alters the Adaptive Value of Flower Longevity in Mimulus guttatus. Am Nat 2014; 183:E50-63. [DOI: 10.1086/674358] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Mitchell RJ, Wilson WG, Holmquist KG, Karron JD. Influence of pollen transport dynamics on sire profiles and multiple paternity in flowering plants. PLoS One 2013; 8:e76312. [PMID: 24098473 PMCID: PMC3789738 DOI: 10.1371/journal.pone.0076312] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 08/23/2013] [Indexed: 11/19/2022] Open
Abstract
In many flowering plants individual fruits contain a mixture of half- and full- siblings, reflecting pollination by several fathers. To better understand the mechanisms generating multiple paternity within fruits we present a theoretical framework linking pollen carryover with patterns of pollinator movement. This 'sire profile' model predicts that species with more extensive pollen carryover will have a greater number of mates. It also predicts that flowers on large displays, which are often probed consecutively during a single pollinator visitation sequence, will have a lower effective number of mates. We compared these predictions with observed values for bumble bee-pollinated Mimulus ringens, which has restricted carryover, and hummingbird-pollinated Ipomopsis aggregata, which has extensive carryover. The model correctly predicted that the effective number of mates is much higher in the species with more extensive carryover. This work extends our knowledge of plant mating systems by highlighting mechanisms influencing the genetic composition of sibships.
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Affiliation(s)
- Randall J. Mitchell
- Department of Biology, University of Akron, Akron, Ohio, United States of America
- * E-mail:
| | - William G. Wilson
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - Karsten G. Holmquist
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States of America
| | - Jeffrey D. Karron
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States of America
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Sun SG, Montgomery BR, Li B. Contrasting effects of plant invasion on pollination of two native species with similar morphologies. Biol Invasions 2013. [DOI: 10.1007/s10530-013-0440-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Runquist RB, Stanton ML. Asymmetric and frequency-dependent pollinator-mediated interactions may influence competitive displacement in two vernal pool plants. Ecol Lett 2012; 16:183-90. [PMID: 23134452 DOI: 10.1111/ele.12026] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 06/04/2012] [Accepted: 10/05/2012] [Indexed: 11/30/2022]
Abstract
A plant species immigrating into a community may experience a rarity disadvantage due to competition for the services of pollinators. These negative reproductive interactions have the potential to lead to competitive displacement or exclusion of a species from a site. In this study, we used one- and two-species arrays of potted plants to test for density and frequency dependence in pollinator-mediated and above-ground intraspecific and interspecific competition between two species of Limnanthes that have overlapping ranges, but rarely occur in close sympatry. There were asymmetric competitive effects; the species responded differently to their frequency within 16-plant replacement series arrays. Limnanthes douglasii rosea experienced stronger reductions in lifetime and per-flower fertility, likely due to pollinator-mediated competition with Limnanthes alba. This effect may be linked to asymmetrical competition through heterospecific pollen transfer. This study demonstrates that pollinator-mediated competition may discourage establishment of L. d. rosea in sites already occupied by its congener.
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Affiliation(s)
- Ryan Briscoe Runquist
- Department of Plant Biology, University of Minnesota, 250 Biological Sciences Center, 1445 Gortner Avenue, St. Paul, MN 55108, USA.
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Eaton DAR, Fenster CB, Hereford J, Huang SQ, Ree RH. Floral diversity and community structure inPedicularis(Orobanchaceae). Ecology 2012. [DOI: 10.1890/11-0501.1] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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King VM, Sargent RD. Presence of an invasive plant species alters pollinator visitation to a native. Biol Invasions 2012. [DOI: 10.1007/s10530-012-0191-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Karron JD, Mitchell RJ. Effects of floral display size on male and female reproductive success in Mimulus ringens. ANNALS OF BOTANY 2012; 109:563-70. [PMID: 21880660 PMCID: PMC3278290 DOI: 10.1093/aob/mcr193] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
BACKGROUND AND AIMS The number of flowers blooming simultaneously on a plant may have profound consequences for reproductive success. Large floral displays often attract more pollinator visits, increasing outcross pollen receipt. However, pollinators frequently probe more flowers in sequence on large displays, potentially increasing self-pollination and reducing pollen export per flower. To better understand how floral display size influences male and female fitness, we manipulated display phenotypes and then used paternity analysis to quantify siring success and selfing rates. METHODS To facilitate unambiguous assignment of paternity, we established four replicate (cloned) arrays of Mimulus ringens, each consisting of genets with unique combinations of homozygous marker genotypes. In each array, we trimmed displays to two, four, eight or 16 flowers. When fruits ripened, we counted the number of seeds per fruit and assigned paternity to 1935 progeny. KEY RESULTS Siring success per flower declined sharply with increasing display size, while female success per flower did not vary with display. The rate of self-fertilization increased for large floral displays, but siring losses due to geitonogamous pollen discounting were much greater than siring gains through increased self-fertilization. As display size increased, each additional seed sired through geitonogamous self-pollination was associated with a loss of 9·7 seeds sired through outcrossing. CONCLUSIONS Although total fitness increased with floral display size, the marginal return on each additional flower declined steadily as display size increased. Therefore, a plant could maximize fitness by producing small displays over a long flowering period, rather than large displays over a brief flowering period.
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Affiliation(s)
- Jeffrey D Karron
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA.
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Muchhala N, Thomson JD. Interspecific competition in pollination systems: costs to male fitness via pollen misplacement. Funct Ecol 2012. [DOI: 10.1111/j.1365-2435.2011.01950.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Livshultz T, Mead JV, Goyder DJ, Brannin M. Climate niches of milkweeds with plesiomorphic traits (Secamonoideae; Apocynaceae) and the milkweed sister group link ancient African climates and floral evolution. AMERICAN JOURNAL OF BOTANY 2011; 98:1966-1977. [PMID: 22074778 DOI: 10.3732/ajb.1100202] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
PREMISE OF THE STUDY Climate change that increases mortality of plants and pollinators can create mate-finding Allee effects and thus act as a strong selective force on floral morphology. Milkweeds (Secamonoideae and Asclepiadoideae; Apocynaceae) are typically small plants of seasonally dry habitats, with pollinia and high pollen-transfer efficiency. Their sister group (tribe Baisseeae and Dewevrella) is mostly comprised of giant lianas of African rainforests, with pollen in monads. Comparison of the two groups motivated a new hypothesis: milkweeds evolved in the context of African aridification and the shifting of rainforest to dry forest. Pollinia and high pollen-transfer efficiency may have been adaptations that alleviated mate-finding Allee effects generated by high mortality during droughts. We formally tested whether milkweeds have a drier climate niche by comparing milkweeds with plesiomorphic traits (Secamonoideae) and the milkweed sister group in continental Africa. METHODS We georeferenced specimens of the milkweed sister group and Secamonoideae in continental Africa, extracted 19 climatic variables from the Worldclim model, conducted factor analysis to identify correlated suites of variables, and compared the frequency distributions of the two lineages relative to each factor. KEY RESULTS The distributions of Secamonoideae and the milkweed sister group differed significantly relative to four factors, each correlated with a distinct suite of climate parameters: (1) air temperature (Secamonoideae: cooler), (2) total and (3) summer precipitation (Secamonoideae: drier), and (4) temperature seasonality and isothermality (Secamonoideae: more seasonal and less isothermal). CONCLUSIONS Secamonoideae in continental Africa inhabit drier, cooler sites than do the milkweed sister group, consistent with a shift from rainforests to dry forests in a cooling climate.
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Affiliation(s)
- Tatyana Livshultz
- The Academy of Natural Sciences of Drexel University, Philadelphia, Pennsylvania 19103, USA.
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Brys R, de Crop E, Hoffmann M, Jacquemyn H. Importance of autonomous selfing is inversely related to population size and pollinator availability in a monocarpic plant. AMERICAN JOURNAL OF BOTANY 2011; 98:1834-1840. [PMID: 22003180 DOI: 10.3732/ajb.1100154] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
PREMISE OF THE STUDY In animal-pollinated plants, autonomous selfing may provide reproductive assurance when pollinators or reproductive partners are limited. Under such circumstances, the contribution of pollinator-mediated seed set to total seed production also may be more variable compared with situations in which pollinator abundances are high or populations consist of large numbers of individuals. Despite the widespread acceptance of the reproductive assurance hypothesis, only limited empirical evidence exists that autonomous selfing confers reproductive output and guarantees constant seed set under variable pollination environments. METHODS We performed emasculation experiments in 22 populations of the short-lived, monocarpic plant Centaurium erythraea in a fragmented dune landscape. KEY RESULTS Floral emasculations resulted in a significantly lower seed set compared with that of intact flowers. Seed set in emasculated flowers also declined significantly with decreasing population size and pollinator availability, whereas seed set of intact flowers did not depend on population size nor on pollinator availability. Variability in seed set among individuals was significantly lower in intact than in emasculated flowers and decreased significantly with increasing population size when flowers were emasculated but not in intact flowers. CONCLUSIONS These results indicate that pollinator-mediated seed set is strongly dependent both on population size and on pollinator availability but that reproductive assurance through autonomous selfing guarantees relatively constant levels of total seed production, even when populations are small and/or pollinator limited. High variation in seed set of emasculated flowers suggests strong unpredictability in pollinator services in small populations.
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Affiliation(s)
- Rein Brys
- Research Institute for Nature and Forest, Kliniekstraat 25, BE-1070 Brussels, Belgium.
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Arceo-Gómez G, Ashman TL. Heterospecific pollen deposition: does diversity alter the consequences? THE NEW PHYTOLOGIST 2011; 192:738-746. [PMID: 21777248 DOI: 10.1111/j.1469-8137.2011.03831.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
• In natural communities, plants can receive pollen from multiple heterospecifics as well as conspecifics. However, studies on the effects of interspecific pollen transfer have focused on interactions between species pairs. The potential exists for diverse interactions among heterospecific pollen (HP) grains on the stigma, and for these to affect plant reproduction, alone or in combination with conspecific pollen (CP) loss, but these interactions have not yet been explored. • We used hand-pollinations to simulate increasing community diversity and CP loss on Mimulus guttatus stigmas. We used pollen mixes of one to three heterospecific donors to determine how species composition and CP load size affect seed production and to characterize the mechanisms underlying fertilization failure. • Heterospecific pollen deposition reduced M. guttatus seed production and while the effect increased with the number of heterospecific donors, the strength depended on species composition and was independent of conspecific load size. Different types of interactions (additive and synergistic) are hypothesized to underlie the diverse effects on M. guttatus reproductive success. • Our results suggest that an increase in the diversity of heterospecific donors will not always lead to a greater decrease in fitness because multispecies effects depend on the interacting species.
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Affiliation(s)
- Gerardo Arceo-Gómez
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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Liao K, Gituru RW, Guo YH, Wang QF. The presence of co-flowering species facilitates reproductive success of Pedicularis monbeigiana (Orobanchaceae) through variation in bumble-bee foraging behaviour. ANNALS OF BOTANY 2011; 108:877-84. [PMID: 21831855 PMCID: PMC3177687 DOI: 10.1093/aob/mcr216] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Accepted: 06/24/2011] [Indexed: 05/20/2023]
Abstract
Background and Aims The presence of co-flowering species can alter pollinator foraging behaviour and, in turn, positively or negatively affect the reproductive success of the focal species. Such interactions were investigated between a focal species, Pedicularis monbeigiana, and a co-flowering species, Vicia dichroantha, which was mediated by behaviour alteration of the shared bumble-bee pollinator. Methods Floral display size and floral colour change of P. monbeigiana were compared between pure (P. monbeigiana only) and mixed (P. monbeigiana and V. dichroantha) plots in two populations. Pollinator visitation rates, interspecific floral switching and successive within-plant pollinator visits were recorded. In addition, supplemental pollination at plant level was performed, and the fruit set and seed set were analysed in pure and mixed plots with different densities of P. monbeigiana. Key Results Pollinator visitation rates were dramatically higher in mixed plots than in pure plots. The higher pollinator visitation rates were recorded in both low- and high-density plots. In particular, successive flower visits within an individual plant were significantly lower in mixed plots. Supplemental pollination significantly increased fruit set and seed set of individuals in pure plots, while it only marginally increased seed set per fruit of plants in mixed plots. Conclusions The presence of V. dichroantha can facilitate pollination and increase female reproductive success of P. monbeigiana via both quantity (mitigating pollinator limitation) and quality (reducing geitonogamy) effects. This study suggests that successive pollinator movements among flowers within a plant, as well as pollinator visitation rates and interspecific flower switching, may be important determinants of the direction and mechanisms of interaction between species.
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Affiliation(s)
- Kuo Liao
- Laboratory of Plant Systematics and Evolutionary Biology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Robert W. Gituru
- Wuhan Botanical Garden, The Chinese Academy of Sciences, Wuhan, 430074, China
| | - You-Hao Guo
- Laboratory of Plant Systematics and Evolutionary Biology, College of Life Sciences, Wuhan University, Wuhan 430072, China
- For correspondence. E-mail or
| | - Qing-Feng Wang
- Wuhan Botanical Garden, The Chinese Academy of Sciences, Wuhan, 430074, China
- For correspondence. E-mail or
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Montgomery BR, Rathcke BJ. Effects of floral restrictiveness and stigma size on heterospecific pollen receipt in a prairie community. Oecologia 2011; 168:449-58. [PMID: 21833640 DOI: 10.1007/s00442-011-2094-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Accepted: 07/20/2011] [Indexed: 11/26/2022]
Abstract
Plant species vary greatly in the degree to which floral morphology restricts access to the flower interior. Restrictiveness of flower corollas may influence heterospecific pollen receipt, but the impact of floral morphology on heterospecific pollen transfer has received little attention. We characterized patterns of pollinator visitation and quantities of conspecific and heterospecific pollen receipt for 29 species with a range of floral morphologies in a prairie community dominated by the introduced plant Euphorbia esula (leafy spurge) which has an unrestrictive morphology. Pollinator overlap was significantly greater between Euphorbia and other unrestrictive flowers than restrictive flowers. Compared to flowers with restrictive morphologies, unrestrictive flowers received significantly more Euphorbia pollen, more heterospecific pollen from other sources, and a greater diversity of pollen species, but not more conspecific pollen. However, stigmatic surface area was significantly larger for flowers with unrestrictive morphologies, and the density of Euphorbia and other heterospecific pollen per stigmatic area did not significantly differ between flower types. These findings suggest that the smaller stigma size in restrictive flowers partly accounts for their decreased heterospecific pollen receipt, but that restrictiveness also allows species to increase the purity of pollen loads they receive. Given that restrictive flowers receive fewer heterospecific pollen grains but at a higher density, the effect of restrictiveness on fecundity depends on whether absolute quantity or density of heterospecific pollen affects fecundity more. Our results also indicate that abundant neighbors are not necessarily important heterospecific pollen sources since Euphorbia pollen was rarely abundant on heterospecifics.
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Affiliation(s)
- Benjamin R Montgomery
- Division of Natural Sciences and Engineering, University of South Carolina Upstate, Spartanburg, SC 29303, USA.
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