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Garlovsky MD, Whittington E, Albrecht T, Arenas-Castro H, Castillo DM, Keais GL, Larson EL, Moyle LC, Plakke M, Reifová R, Snook RR, Ålund M, Weber AAT. Synthesis and Scope of the Role of Postmating Prezygotic Isolation in Speciation. Cold Spring Harb Perspect Biol 2024; 16:a041429. [PMID: 38151330 PMCID: PMC11444258 DOI: 10.1101/cshperspect.a041429] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
How barriers to gene flow arise and are maintained are key questions in evolutionary biology. Speciation research has mainly focused on barriers that occur either before mating or after zygote formation. In comparison, postmating prezygotic (PMPZ) isolation-a barrier that acts after gamete release but before zygote formation-is less frequently investigated but may hold a unique role in generating biodiversity. Here we discuss the distinctive features of PMPZ isolation, including the primary drivers and molecular mechanisms underpinning PMPZ isolation. We then present the first comprehensive survey of PMPZ isolation research, revealing that it is a widespread form of prezygotic isolation across eukaryotes. The survey also exposes obstacles in studying PMPZ isolation, in part attributable to the challenges involved in directly measuring PMPZ isolation and uncovering its causal mechanisms. Finally, we identify outstanding knowledge gaps and provide recommendations for improving future research on PMPZ isolation. This will allow us to better understand the nature of this often-neglected reproductive barrier and its contribution to speciation.
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Affiliation(s)
- Martin D Garlovsky
- Applied Zoology, Faculty of Biology, Technische Universität Dresden, Dresden 01062, Germany
| | | | - Tomas Albrecht
- Institute of Vertebrate Biology, Czech Academy of Sciences, Brno 60365, Czech Republic
- Department of Zoology, Faculty of Science, Charles University, Prague 128 00, Czech Republic
| | - Henry Arenas-Castro
- School of Biological Sciences, University of Queensland, St Lucia 4072, Queensland, Australia
| | - Dean M Castillo
- Department of Biological Sciences, Miami University, Hamilton, Ohio 45011, USA
| | - Graeme L Keais
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Erica L Larson
- Department of Biological Sciences, University of Denver, Denver, Colorado 80208, USA
| | - Leonie C Moyle
- Department of Biology, Indiana University Bloomington, Indiana 47405, USA
| | - Melissa Plakke
- Division of Science, Mathematics, and Technology, Governors State University, University Park, Illinois 60484, USA
| | - Radka Reifová
- Department of Zoology, Faculty of Science, Charles University, Prague 128 00, Czech Republic
| | - Rhonda R Snook
- Department of Zoology, Stockholm University, Stockholm 109 61, Sweden
| | - Murielle Ålund
- Department of Ecology and Genetics, Animal Ecology, Uppsala University, Uppsala 75236, Sweden
| | - Alexandra A-T Weber
- Department of Aquatic Ecology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf 8600, Zürich, Switzerland
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Fang Q, Wu J, Zhang T, Ba S, Zhao C, Dai P. Flower visits and pollinator pollen load networks reveal the effects of pollinator sharing on heterospecific pollen transfer in a subalpine plant community. Ecol Evol 2024; 14:e11244. [PMID: 38590550 PMCID: PMC10999945 DOI: 10.1002/ece3.11244] [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: 09/29/2023] [Revised: 03/05/2024] [Accepted: 03/22/2024] [Indexed: 04/10/2024] Open
Abstract
The mutualistic network of plant-pollinator also involves interspecific pollination caused by pollinator sharing. Plant-pollinator networks are commonly based on flower visit observations, which may not adequately represent the actual pollen transfer between co-flowering plant species. Here, we compared the network structure of plant-pollinator interactions based on flower visits (FV) and pollen loads (PL) on the bodies of pollinators and tested how the degree of pollinator sharing in the two networks affected heterospecific pollen transfer (HPT) between plant species in a subalpine meadow. The FV and PL networks were largely overlapped. PL network included more links than FV network. The positions of plant and pollinator species in the FV and PL networks were positively correlated, indicating that both networks could detect major plant-pollinator interactions. The degree of pollinator sharing, based on either the FV or the PL network, positively influenced the amount of heterospecific pollen transferred between plant species pairs. However, the degree of pollinator sharing had a low overall explanatory power for HPT, and the explanatory powers of the FV and PL networks were similar. Overall, our study highlights the importance of FV and PL for understanding the drivers and outcomes of plant-pollinator interactions, as well as their relevance to HPT.
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Affiliation(s)
- Qiang Fang
- College of AgricultureHenan University of Science and TechnologyLuoyangChina
| | - Jiajun Wu
- College of AgricultureHenan University of Science and TechnologyLuoyangChina
| | - Tao Zhang
- Ministry of Education Key Laboratory for Transboundary Ecosecurity of Southwest China, Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology, Institute of Biodiversity, School of Ecology and Environmental ScienceYunnan UniversityKunmingYunnanChina
| | - Suyan Ba
- College of AgricultureHenan University of Science and TechnologyLuoyangChina
| | - Chunyan Zhao
- College of AgricultureHenan University of Science and TechnologyLuoyangChina
| | - Panfeng Dai
- College of AgricultureHenan University of Science and TechnologyLuoyangChina
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Zhang QY, Chen Z, Sun H, Niu Y. Intraspecific floral colour variation in three Pedicularis species. PLANT DIVERSITY 2024; 46:274-279. [PMID: 38807915 PMCID: PMC11128843 DOI: 10.1016/j.pld.2023.03.011] [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: 12/14/2022] [Revised: 03/28/2023] [Accepted: 03/29/2023] [Indexed: 05/30/2024]
Abstract
Flower constancy describes the phenomenon that pollinators tend to successively visit flowers of a single species during foraging, reducing reproductive interference in natural communities. The extent of flower constancy is largely determined by the floral traits of co-flowering species. Both higher inter-specific and lower intraspecific differences of floral traits should contribute to a higher level of flower constancy. However, previous studies mainly focused on interspecific difference, and the intraspecific variation (consistency) of floral traits received much less attention. We hypothesise that selection may favour lower intraspecific floral trait variation in communities composed of multiple co-flowering congeners. We investigated the floral colour variation of three focal Pedicularis species that share pollinators in 19 communities composed of either single or multiple Pedicularis species. Colour was quantified using image-based colour analysis as perceived by pollinators. We found that most of the intrapopulation floral colour variation was below the colour discrimination threshold of bumblebees, implying strongly constrained by the visual selection by pollinators. Contrary to the hypothesis, there is no significant difference in intraspecific floral colour variation between different community contexts. It may be due to the relatively large interspecific floral colour differences of most co-flowering species. The influence of community context on intraspecific variation may be reflected in floral traits other than colours.
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Affiliation(s)
- Qiu-Yu Zhang
- State Key Laboratory of Plant Diversity and Specialty Crops, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, Yunnan, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhe Chen
- State Key Laboratory of Plant Diversity and Specialty Crops, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, Yunnan, China
| | - Hang Sun
- State Key Laboratory of Plant Diversity and Specialty Crops, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, Yunnan, China
| | - Yang Niu
- State Key Laboratory of Plant Diversity and Specialty Crops, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, Yunnan, China
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Swensen SM, Gomez AM, Piasecki-Masters C, Chime N, Wine AR, Rodriguez NC, Conklin J, Melcher PJ. Minimal impacts of invasive Scaevola taccada on Scaevola plumieri via pollinator competition in Puerto Rico. FRONTIERS IN PLANT SCIENCE 2024; 15:1281797. [PMID: 38332769 PMCID: PMC10850390 DOI: 10.3389/fpls.2024.1281797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 01/04/2024] [Indexed: 02/10/2024]
Abstract
Introduction Scaevola taccada and Scaevola plumieri co-occur on shorelines of the Caribbean. Scaevola taccada is introduced in this habitat and directly competes with native dune vegetation, including S. plumieri, a species listed as locally endangered and threatened in Caribbean locations. This study addresses whether the invasive S. taccada also impacts the native S. plumieri indirectly by competing for pollinators and represents the first comparative study of insect visitation between these species. Methods Insect visitation rates were measured at sites where species co-occur and where only the native occurs. Where species cooccur, insect visitors were captured, identified and analyzed for the pollen they carry. Pollen found on open-pollinated flowers was analyzed to assess pollen movement between the two species. We also compared floral nectar from each species by measuring volume, sugar content, and presence and proportions of amine group containing constituents (AGCCs). Results Our results demonstrate that both species share insect visitors providing the context for possible pollinator competition, yet significant differences in visitation frequency were not found. We found evidence of asymmetrical heterospecific pollen deposition in the native species, suggesting a possible reproductive impact. Insect visitation rates for the native were not significantly different between invaded and uninvaded sites, suggesting that the invasive S. taccada does not limit pollinator visits to S. plumieri. Comparisons of nectar rewards from the invasive and the native reveal similar volumes and sugar concentrations, but significant differences in some amine group containing constituents that may enhance pollinator attraction. Conclusion Our analysis finds no evidence for pollination competition and therefore S. taccada's main impacts on S. plumieri are through competitive displacement and possibly through reproductive impacts as a consequence of heterospecific pollen deposition.
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Affiliation(s)
- Susan M. Swensen
- Department of Biology, Ithaca College, Ithaca, NY, United States
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Hao K, Fang Q, Huang SQ. Do Silene species with exposed stigmas tolerate interference by heterospecific pollen? AMERICAN JOURNAL OF BOTANY 2023:e16147. [PMID: 36827179 DOI: 10.1002/ajb2.16147] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 02/02/2023] [Accepted: 02/02/2023] [Indexed: 05/22/2023]
Abstract
PREMISE Co-flowering species that have not evolved an avoidance mechanism may have tolerance to heterospecific pollen (HP) deposition as an adaptive strategy to minimize any deleterious effects of HP transfer, but empirical evidence for the tolerance hypothesis remains scarce. METHODS To estimate the potential effects of heterospecific pollen deposition (HPD) on female reproductive success, we counted conspecific (CP) and HP pollen grains deposited on stigmas and assessed subsequent seed set of both open- and hand-pollinated flowers in three co-flowering Silene species with exposed stigmas that usually received numerous HP grains on the elongated receptive area. RESULTS The percentage of HP grains per flower (HP%) varied from 16.6% to 43.0% among three species. Silene chungtienensis had lower HP%, and the CP-HP relationship was neutral; S. gracilicaulis and S. yunnanensis had a relatively higher HP% with a positive CP-HP relationship. The effects of CP and HP number on natural seed set were positive for all three species, but HP% had stronger negative effects in S. chungtienensis and S. gracilicaulis. In hand-pollinated flowers of the three Silene species, seed set did not decrease with HP whether CP was in excess or insufficient, indicating no negative effects of HPD on seed production. CONCLUSIONS Consistent with the tolerance hypothesis, our results indicated that species with higher HP interference are likely to be tolerant to an increase in HP%. These species with generalist-pollinated flowers and exposed large stigmas may benefit from an increase of conspecific pollen deposition, despite the associated increase in heterospecific pollen deposition.
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Affiliation(s)
- Kai Hao
- Institute of Evolution and Ecology, School of Life Sciences, Central China Normal University, Wuhan, 430079, China
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Qiang Fang
- College of Agriculture, Henan University of Science and Technology, Luoyang, 471003, China
| | - Shuang-Quan Huang
- Institute of Evolution and Ecology, School of Life Sciences, Central China Normal University, Wuhan, 430079, China
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Cardoso JCF, Trevizan R, Matallana-Puerto CA, Gonçalves RV, Oliveira PE, Coelho CP, Matias R. Do distylous syntopic plant species partition their floral morphological traits? Biol J Linn Soc Lond 2022. [DOI: 10.1093/biolinnean/blac072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Morphological niche partitioning between related syntopic plants that are distylous (with short- and long-styled morphs) is complex. Owing to differences in the heights of stigmas and anthers, each floral morph must place pollen onto two distinct parts of the body of the pollinator. This led us to hypothesize that such partitioning should be more accurate among distylous syntopic species in comparison to combinations with other related plants that do not co-occur. We tested these assumptions using a set of Palicourea (Rubiaceae) species as a model system. We compared the distribution, flowering phenology, floral measurements and reciprocity of sexual organ heights of two syntopic species (Palicourea rigida and Palicourea coriacea) and one non-syntopic congener (Palicourea marcgravii). The three species overlapped in their distributions and flowering periods. The position of sexual organs was, in most cases, partitioned between syntopic populations, with low overlap in anther and stigma heights. However, we found a higher overlap involving the non-syntopic species, especially between Palicourea rigida and Palicourea marcgravii. Additionally, reciprocity of sexual organs was more accurate in intraspecific inter-morph combinations (i.e. legitimate organ correspondence) in comparison to intraspecific intra-morph, interspecific syntopic and interspecific non-syntopic combinations. The partitioning of morphological traits between syntopic species might facilitate the differential placement of pollen on the body of the pollinator and reduce the chances of interspecific interference.
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Affiliation(s)
- João Custódio Fernandes Cardoso
- Programa de Pós-Graduação em Ecologia e Conservação de Recursos Naturais, Universidade Federal de Uberlândia , Uberlândia, MG , Brazil
| | - Renata Trevizan
- Programa de Pós-Graduação em Biologia Vegetal, Universidade Estadual de Campinas , Campinas, SP , Brazil
| | | | - Rogério Victor Gonçalves
- Centre for Sustainable Ecosystem Solutions, University of Wollongong , Wollongong , NSW , Australia
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Zou TT, Wang CH, Lyu ST, Yu X, Deng LX, Liu WQ, Dai J, Wang XF. Effects of heterospecific pollen on stigma behavior in Campsis radicans: Causes and consequences. AMERICAN JOURNAL OF BOTANY 2022; 109:1004-1015. [PMID: 35567497 DOI: 10.1002/ajb2.1865] [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: 09/12/2021] [Revised: 04/18/2022] [Accepted: 04/19/2022] [Indexed: 06/15/2023]
Abstract
PREMISE Pollinator sharing of co-flowering plants may result in interspecific pollen receipt with a fitness cost. However, the underlying factors that determine the effects of heterospecific pollen (HP) are not fully understood. Moreover, the cost of stigma closure induced by HP may be more severe for plants with special touch-sensitive stigmas than for plants with non-touch-sensitive stigmas. Very few studies have assessed HP effects on stigma behavior. METHODS We conducted hand-pollination experiments with 10 HP donors to estimate HP effects on stigma behavior and stigmatic pollen germination in Campsis radicans (Bignoniaceae) at low and high pollen loads. We assessed the role of phylogenetic distance between donor and recipient, pollen size, and pollen aperture number in mediating HP effects. Additionally, we observed pollen tube growth to determine the conspecific pollen-tube-growth advantage. RESULTS Stigma behavior differed significantly with HP of different species. Pollen load increased, while pollen size decreased, the percentage of permanent closure and stigmatic germination of HP. Stigmatic HP germination increased with increasing aperture number. However, HP effects did not depend on phylogenetic distance. In addition, conspecific pollen had a pollen-tube-growth advantage over HP. CONCLUSIONS Our results provide a good basis for understanding the stigma-pollen recognition process of plant taxa with touch-sensitive stigmas. We concluded that certain flowering traits drive the HP effects on the post-pollination period. To better understand the impact of pollinator sharing and interspecific pollen transfer on plant evolution, we highlight the importance of evaluating more factors that determine HP effects at the community level.
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Affiliation(s)
- Ting-Ting Zou
- Laboratory of Plant Systematics and Evolutionary Biology, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Chun-Hui Wang
- Ecology and Environment Monitoring and Scientific Research Center, Yangtze Basin Ecology and Environment Administration, Ministry of Ecology and Environment of the People's Republic of China, Wuhan, 430010, China
| | - Sen-Tao Lyu
- Laboratory of Plant Systematics and Evolutionary Biology, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Xiaolei Yu
- State Key Laboratory of Hybrid Rice, Laboratory of Plant Systematics and Evolutionary Biology, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Lu-Xi Deng
- Laboratory of Plant Systematics and Evolutionary Biology, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Wei-Qi Liu
- Laboratory of Plant Systematics and Evolutionary Biology, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Jie Dai
- Laboratory of Plant Systematics and Evolutionary Biology, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Xiao-Fan Wang
- Laboratory of Plant Systematics and Evolutionary Biology, College of Life Sciences, Wuhan University, Wuhan, 430072, China
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Pontes CADS, Domingos-Melo A, Milet-Pinheiro P, Navarro DMDAF, Lima Nadia T, Machado IC. Staminode of Jacaranda rugosa A.H. Gentry (Bignoniaceae) promotes functional specialization by ensuring signaling and mechanical fit to medium-sized bees. ORG DIVERS EVOL 2022. [DOI: 10.1007/s13127-022-00558-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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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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Lopes SA, Bergamo PJ, Najara Pinho Queiroz S, Ollerton J, Santos T, Rech AR. Heterospecific pollen deposition is positively associated with reproductive success in a diverse hummingbird‐pollinated plant community. OIKOS 2021. [DOI: 10.1111/oik.08714] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sabrina Aparecida Lopes
- Centre of Advanced Studies in Functioning of Ecological Systems and Interactions (CAFESIN), Programa de Pós‐Graduação em Biologia Animal, Univ. Federal dos Vales do Jequitinhonha e Mucuri UFVJM, Diamantina Minas Gerais Brazil
| | | | - Steffani Najara Pinho Queiroz
- Centre of Advanced Studies in Functioning of Ecological Systems and Interactions (CAFESIN), Programa de Pós‐Graduação em Biologia Animal, Univ. Federal dos Vales do Jequitinhonha e Mucuri UFVJM, Diamantina Minas Gerais Brazil
| | - Jeff Ollerton
- Faculty of Arts, Science and Technology, Univ. of Northampton, Waterside Campus Northampton UK
| | - Thiago Santos
- Centre of Advanced Studies in Functioning of Ecological Systems and Interactions (CAFESIN), Programa de Pós‐Graduação em Biologia Animal, Univ. Federal dos Vales do Jequitinhonha e Mucuri UFVJM, Diamantina Minas Gerais Brazil
| | - André Rodrigo Rech
- Centre of Advanced Studies in Functioning of Ecological Systems and Interactions (CAFESIN), Programa de Pós‐Graduação em Biologia Animal, Univ. Federal dos Vales do Jequitinhonha e Mucuri UFVJM, Diamantina Minas Gerais Brazil
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Pollination success increases with plant diversity in high-Andean communities. Sci Rep 2021; 11:22107. [PMID: 34764375 PMCID: PMC8586006 DOI: 10.1038/s41598-021-01611-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 10/27/2021] [Indexed: 11/25/2022] Open
Abstract
Pollinator-mediated plant–plant interactions have traditionally been viewed within the competition paradigm. However, facilitation via pollinator sharing might be the rule rather than the exception in harsh environments. Moreover, plant diversity could be playing a key role in fostering pollinator-mediated facilitation. Yet, the facilitative effect of plant diversity on pollination remains poorly understood, especially under natural conditions. By examining a total of 9371 stigmas of 88 species from nine high-Andean communities in NW Patagonia, we explored the prevalent sign of the relation between conspecific pollen receipt and heterospecific pollen diversity, and assessed whether the incidence of different outcomes varies with altitude and whether pollen receipt relates to plant diversity. Conspecific pollen receipt increased with heterospecific pollen diversity on stigmas. In all communities, species showed either positive or neutral but never negative relations between the number of heterospecific pollen donor species and conspecific pollen receipt. The incidence of species showing positive relations increased with altitude. Finally, stigmas collected from communities with more co-flowering species had richer heterospecific pollen loads and higher abundance of conspecific pollen grains. Our findings suggest that plant diversity enhances pollination success in high-Andean plant communities. This study emphasizes the importance of plant diversity in fostering indirect plant–plant facilitative interactions in alpine environments, which could promote species coexistence and biodiversity maintenance.
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Pollination generalization and reproductive assurance by selfing in a tropical montane ecosystem. Naturwissenschaften 2021; 108:50. [PMID: 34626232 DOI: 10.1007/s00114-021-01764-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 09/22/2021] [Accepted: 09/29/2021] [Indexed: 10/20/2022]
Abstract
Pollination and reproduction are important processes for understanding plant community dynamics. Information regarding pollination and reproduction is urgent for threatened ecosystems, such as tropical montane ecosystems. In tropical mountains, pollination patterns are expected to conform to the reproductive assurance theory (due to low pollinator activity) and old, climatically buffered and infertile landscapes (OCBIL) theory (due to restricted plant range size). For 82 plant species of the Itatiaia National Park (including endemic and endangered species), we evaluated at least one of the following features: pollinator identity, flower color and size, flowering phenology, and pollinator dependence. Most plant species (ca. 60%) were pollinated by two or more functional groups of pollinators (generalized pollination), with high importance of flies as pollinators. There was low pollinator activity overall (less than one visit per flower per hour). Notably, the invasive honeybee Apis mellifera L. performed half of the visits to this entire plant community, suggesting an impact on the native pollinator fauna and consequently on the native flora. Most endemic plants were generalized with white and small flowers, while endangered species were pollination-specialized with colorful and large flowers. Thus, endangered species are susceptible to changes in pollinator fauna. Flowering seasonality reflected the importance of climatic constraints in this environment. One-third of the plant species were autogamous. Our data suggest that pollinator scarcity may have promoted reproductive assurance strategies such as generalization and pollinator independence. Our community-level study highlighted consistent pollination patterns for tropical mountains and emphasized threats for specialized endangered species.
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Unexpectedly low paternal diversity is associated with infrequent pollinator visitation for a bird-pollinated plant. Oecologia 2021; 196:937-950. [PMID: 33870456 DOI: 10.1007/s00442-021-04906-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 03/23/2021] [Indexed: 10/21/2022]
Abstract
The behaviour of pollinators has important consequences for plant mating. Nectar-feeding birds often display behaviour that results in more pollen carryover than insect pollinators, which is predicted to result in frequent outcrossing and high paternal diversity for bird-pollinated plants. We tested this prediction by quantifying mating system parameters and bird visitation in three populations of an understory bird-pollinated herb, Anigozanthos humilis (Haemodoraceae). Microsatellite markers were used to genotype 131 adult plants, and 211 seeds from 23 maternal plants, from three populations. While outcrossing rates were high, estimates of paternal diversity were surprisingly low compared with other bird-pollinated plants. Despite nectar-feeding birds being common at the study sites, visits to A. humilis flowers were infrequent (62 visits over 21,552 recording hours from motion-triggered cameras, or equivalent to one visit per flower every 10 days), and the majority (76%) were by a single species, the western spinebill Acanthorhynchus superciliosus (Meliphagidae). Pollen counts from 30 captured honeyeaters revealed that A. humilis comprised just 0.3% of the total pollen load. For 10 western spinebills, A. humilis pollen comprised only 4.1% of the pollen load, which equated to an average of 3.9 A. humilis pollen grains per bird. Taken together, our findings suggest that low visitation rates and low pollen loads of floral visitors have led to the low paternal diversity observed in this understory bird-pollinated herb. As such, we shed new light on the conditions that can lead to departures from high paternal diversity for plants competing for the pollination services of generalist nectar-feeding birds.
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