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Ballarin CS, Fontúrbel FE, Rech AR, Oliveira PE, Goés GA, Polizello DS, Oliveira PH, Hachuy-Filho L, Amorim FW. How many animal-pollinated angiosperms are nectar-producing? THE NEW PHYTOLOGIST 2024; 243:2008-2020. [PMID: 38952269 DOI: 10.1111/nph.19940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Accepted: 06/17/2024] [Indexed: 07/03/2024]
Abstract
The diversity of plant-pollinator interactions is grounded in floral resources, with nectar considered one of the main floral rewards plants produce for pollinators. However, a global evaluation of the number of animal-pollinated nectar-producing angiosperms and their distribution world-wide remains elusive. We compiled a thorough database encompassing 7621 plant species from 322 families to estimate the number and proportion of nectar-producing angiosperms reliant on animal pollination. Through extensive sampling of plant communities, we also explored the interplay between nectar production, floral resource diversity, latitudinal and elevational gradients, contemporary climate, and environmental characteristics. Roughly 223 308 animal-pollinated angiosperms are nectar-producing, accounting for 74.4% of biotic-pollinated species. Global distribution patterns of nectar-producing plants reveal a distinct trend along latitudinal and altitudinal gradients, with increased proportions of plants producing nectar in high latitudes and altitudes. Conversely, tropical communities in warm and moist climates exhibit greater floral resource diversity and a lower proportion of nectar-producing plants. These findings suggest that ecological trends driven by climate have fostered the diversification of floral resources in warmer and less seasonal climates, reducing the proportion of solely nectar-producing plants. Our study provides a baseline for understanding plant-pollinator relationships, plant diversification, and the distribution of plant traits.
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Affiliation(s)
- Caio S Ballarin
- Laboratório de Ecologia da Polinização e Interações - LEPI, Departamento de Biodiversidade e Bioestatística, Instituto de Biociências, Universidade Estadual Paulista 'Júlio de Mesquita Filho' (IBB - UNESP), Rua Prof. Dr Antonio Celso Wagner Zanin, Botucatu, SP, CEP 18618-689, Brazil
- Programa de Pós-graduação em Biologia Vegetal, IBB - UNESP, Rua Prof. Dr Antonio Celso Wagner Zanin, Botucatu, SP, CEP 18618-689, Brazil
| | - Francisco E Fontúrbel
- Instituto de Biología, Pontificia Universidad Católica de Valparaíso, Av. Universidad 330, Valparaíso, CEP 2373223, Chile
- Millennium Nucleus of Patagonian Limit of Life (LiLi), Valdivia, CEP 5090000, Chile
| | - André R Rech
- Programas de Pós-Graduação em Biologia Animal, Estudos Rurais e Ciências Florestais, Faculdade Interdisciplinar em Humanidades, Universidade Federal dos Vales do Jequitinhonha e Mucuri, Diamantina, MG, CEP 39100-000, Brazil
| | - Paulo E Oliveira
- Instituto de Biologia, Universidade Federal de Uberlândia, Uberlândia, MG, CEP 38405302, Brazil
| | - Guilherme Alcarás Goés
- Laboratório de Ecologia da Polinização e Interações - LEPI, Departamento de Biodiversidade e Bioestatística, Instituto de Biociências, Universidade Estadual Paulista 'Júlio de Mesquita Filho' (IBB - UNESP), Rua Prof. Dr Antonio Celso Wagner Zanin, Botucatu, SP, CEP 18618-689, Brazil
- Laboratório de Restauração Florestal - LERF, Faculdade de Ciências Agronômicas, Universidade Estadual Paulista 'Júlio de Mesquita Filho' (UNESP), Botucatu, SP, CEP 18610-034, Brazil
| | - Diego S Polizello
- Laboratório de Ecologia da Polinização e Interações - LEPI, Departamento de Biodiversidade e Bioestatística, Instituto de Biociências, Universidade Estadual Paulista 'Júlio de Mesquita Filho' (IBB - UNESP), Rua Prof. Dr Antonio Celso Wagner Zanin, Botucatu, SP, CEP 18618-689, Brazil
- Programa de Pós-graduação em Zoologia, IBB - UNESP, Rua Prof. Dr Antonio Celso Wagner Zanin, Botucatu, São Paulo, CEP 18618-689, Brazil
| | - Pablo H Oliveira
- Laboratório de Ecologia da Polinização e Interações - LEPI, Departamento de Biodiversidade e Bioestatística, Instituto de Biociências, Universidade Estadual Paulista 'Júlio de Mesquita Filho' (IBB - UNESP), Rua Prof. Dr Antonio Celso Wagner Zanin, Botucatu, SP, CEP 18618-689, Brazil
- Programa de Pós-graduação em Zoologia, IBB - UNESP, Rua Prof. Dr Antonio Celso Wagner Zanin, Botucatu, São Paulo, CEP 18618-689, Brazil
| | - Leandro Hachuy-Filho
- Laboratório de Ecologia da Polinização e Interações - LEPI, Departamento de Biodiversidade e Bioestatística, Instituto de Biociências, Universidade Estadual Paulista 'Júlio de Mesquita Filho' (IBB - UNESP), Rua Prof. Dr Antonio Celso Wagner Zanin, Botucatu, SP, CEP 18618-689, Brazil
- Programa de Pós-graduação em Zoologia, IBB - UNESP, Rua Prof. Dr Antonio Celso Wagner Zanin, Botucatu, São Paulo, CEP 18618-689, Brazil
| | - Felipe W Amorim
- Laboratório de Ecologia da Polinização e Interações - LEPI, Departamento de Biodiversidade e Bioestatística, Instituto de Biociências, Universidade Estadual Paulista 'Júlio de Mesquita Filho' (IBB - UNESP), Rua Prof. Dr Antonio Celso Wagner Zanin, Botucatu, SP, CEP 18618-689, Brazil
- Programa de Pós-graduação em Biologia Vegetal, IBB - UNESP, Rua Prof. Dr Antonio Celso Wagner Zanin, Botucatu, SP, CEP 18618-689, Brazil
- Programa de Pós-graduação em Zoologia, IBB - UNESP, Rua Prof. Dr Antonio Celso Wagner Zanin, Botucatu, São Paulo, CEP 18618-689, Brazil
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Cromie J, Ternest JJ, Komatz AP, Adunola PM, Azevedo C, Mallinger RE, Muñoz PR. Genotypic variation in blueberry flower morphology and nectar reward content affects pollinator attraction in a diverse breeding population. BMC PLANT BIOLOGY 2024; 24:814. [PMID: 39210281 PMCID: PMC11360736 DOI: 10.1186/s12870-024-05495-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Accepted: 08/07/2024] [Indexed: 09/04/2024]
Abstract
BACKGROUND Pollination is crucial to obtaining optimal blueberry yield and fruit quality. Despite substantial investments in seasonal beekeeping services, blueberry producers consistently report suboptimal pollinator visitation and fruit set in some cultivars. Flower morphology and floral rewards are among the key factors that have shown to contribute to pollinator attraction, however little is known about their relative importance for improving yield in the context of plant breeding. Clarifying the relationships between flower morphology, nectar reward content, pollinator recruitment, and pollination outcomes, as well as their genetic components, can inform breeding priorities for enhancing blueberry production. In the present study, we measured ten flower and nectar traits and indices of successful pollination, including fruit set, seed count, and fruit weight in 38 southern highbush blueberry genotypes. Additionally, we assessed pollinator visitation frequency and foraging behavior over two growing seasons. Several statistical models were tested to optimize the prediction of pollinator visitation and pollination success, including partial least squares, BayesB, ridge-regression, and random forest. RESULTS Random forest models obtained high predictive abilities for pollinator visitation frequency, with values of 0.54, 0.52, and 0.66 for honey bee, bumble bee, and total pollinator visits, respectively. The BayesB model provided the most consistent prediction of fruit set, fruit weight, and seed set, with predictive abilities of 0.07, -0.08, and 0.42, respectively. Variable importance analysis revealed that genotypic differences in nectar volume had the greatest impact on honey bee and bumble bee visitation, although preferences for flower morphological traits varied depending on the foraging task. Flower density was a major driving factor attracting nectar-foraging honey bees and bumble bees, while pollen-foraging bumble bees were most influenced by flower accessibility, specifically corolla length and the length-to-width ratio. CONCLUSIONS Honey bees comprised the majority of pollinator visits, and were primarily influenced by nectar volume and flower density. Corolla length and the length-to-width ratio were also identified as the main predictors of fruit set, fruit weight, seed count, as well as pollen-foraging bumble bee visits, suggesting that these bees and their foraging preferences may play a pivotal role in fruit production. Moderate to high narrow-sense heritability values (ranging from 0.30 to 0.77) were obtained for all floral traits, indicating that selective breeding efforts may enhance cultivar attractiveness to pollinators.
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Affiliation(s)
- Juliana Cromie
- Department of Horticultural Sciences, University of Florida, Gainesville, FL, USA
| | - John J Ternest
- Department of Entomology and Nematology, University of Florida, Gainesville, FL, USA
| | - Andrew P Komatz
- Department of Horticultural Sciences, University of Florida, Gainesville, FL, USA
| | - Paul M Adunola
- Department of Horticultural Sciences, University of Florida, Gainesville, FL, USA
| | - Camila Azevedo
- Department of Horticultural Sciences, University of Florida, Gainesville, FL, USA
- Department of Statistics, Federal University of Viçosa, Viçosa, MG, Brazil
| | - Rachel E Mallinger
- Department of Entomology and Nematology, University of Florida, Gainesville, FL, USA
| | - Patricio R Muñoz
- Department of Horticultural Sciences, University of Florida, Gainesville, FL, USA.
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Romero-Bravo A, Castellanos MC. Nectar and floral morphology differ in evolutionary potential in novel pollination environments. THE NEW PHYTOLOGIST 2024; 243:753-764. [PMID: 38714871 DOI: 10.1111/nph.19780] [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: 02/13/2024] [Accepted: 03/25/2024] [Indexed: 06/21/2024]
Abstract
Plants can evolve rapidly after pollinator changes, but the response of different floral traits to novel selection can vary. Floral morphology is often expected to show high integration to maintain pollination accuracy, while nectar traits can be more environmentally sensitive. The relative role of genetic correlations and phenotypic plasticity (PP) in floral evolution remains unclear, particularly for nectar traits, and can be studied in the context of recent pollinator changes. Digitalis purpurea shows rapid recent evolution of corolla morphology but not nectar traits following a range expansion with hummingbirds added as pollinators. We use this species to compare PP, heritability, evolvability and integration of floral morphology and nectar in a common garden. Morphological traits showed higher heritability than nectar traits, and the proximal section of the corolla, which regulates access to nectar and underwent rapid change in introduced populations, presented lower integration than the rest of the floral phenotype. Nectar was more plastic than morphology, driven by highly plastic sugar concentration. Nectar production rate showed high potential to respond to selection. These results explain the differential rapid evolution of floral traits previously observed in this species and show how intrafloral modularity determines variable evolutionary potential in morphological and nectar traits.
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Affiliation(s)
- Andrés Romero-Bravo
- Department of Ecology & Evolution, School of Life Sciences, University of Sussex, Brighton, BN1 9QG, UK
| | - Maria Clara Castellanos
- Department of Ecology & Evolution, School of Life Sciences, University of Sussex, Brighton, BN1 9QG, UK
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Liu Y, Dunker S, Durka W, Dominik C, Heuschele JM, Honchar H, Hoffmann P, Musche M, Paxton RJ, Settele J, Schweiger O. Eco-evolutionary processes shaping floral nectar sugar composition. Sci Rep 2024; 14:13856. [PMID: 38879632 PMCID: PMC11180116 DOI: 10.1038/s41598-024-64755-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 06/12/2024] [Indexed: 06/19/2024] Open
Abstract
Floral nectar sugar composition is assumed to reflect the nutritional demands and foraging behaviour of pollinators, but the relative contributions of evolutionary and abiotic factors to nectar sugar composition remain largely unknown across the angiosperms. We compiled a comprehensive dataset on nectar sugar composition for 414 insect-pollinated plant species across central Europe, along with phylogeny, paleoclimate, flower morphology, and pollinator dietary demands, to disentangle their relative effects. We found that phylogeny was strongly related with nectar sucrose content, which increased with the phylogenetic age of plant families, but even more strongly with historic global surface temperature. Nectar sugar composition was also defined by floral morphology, though it was not related to our functional measure of pollinator dietary demands. However, specialist pollinators of current plant-pollinator networks predominantly visited plant species with sucrose-rich nectar. Our results suggest that both physiological mechanisms related to plant water balance and evolutionary effects related to paleoclimatic changes have shaped floral nectar sugar composition during the radiation and specialisation of plants and pollinators. As a consequence, the high velocity of current climate change may affect plant-pollinator interaction networks due to a conflicting combination of immediate physiological responses and phylogenetic conservatism.
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Affiliation(s)
- Yicong Liu
- Department of Community Ecology, Helmholtz-Centre for Environmental Research-UFZ, Halle (Saale), Germany.
- Institute for Biology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany.
| | - Susanne Dunker
- Department of Physiological Diversity, Helmholtz-Centre for Environmental Research-UFZ, Leipzig, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
| | - Walter Durka
- Department of Community Ecology, Helmholtz-Centre for Environmental Research-UFZ, Halle (Saale), Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
| | - Christophe Dominik
- Department of Community Ecology, Helmholtz-Centre for Environmental Research-UFZ, Halle (Saale), Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
| | - Jonna M Heuschele
- Department of Community Ecology, Helmholtz-Centre for Environmental Research-UFZ, Halle (Saale), Germany
- Institute for Biology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
- Department of Biodiversity and People, German Centre for Integrative Biodiversity Research-Jena-Leipzig, Leipzig, Germany
| | - Hanna Honchar
- Department of Conservation Biology and Social-Ecological Systems, Helmholtz Centre for Environmental Research-UFZ, Halle (Saale), Germany
- Department of Ecological Monitoring, Institute for Evolutionary Ecology, NAS Ukraine, Kyiv, Ukraine
| | - Petra Hoffmann
- Department of Physiological Diversity, Helmholtz-Centre for Environmental Research-UFZ, Leipzig, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
| | - Martin Musche
- Department of Conservation Biology and Social-Ecological Systems, Helmholtz Centre for Environmental Research-UFZ, Halle (Saale), Germany
| | - Robert J Paxton
- Institute for Biology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
| | - Josef Settele
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
- Department of Conservation Biology and Social-Ecological Systems, Helmholtz Centre for Environmental Research-UFZ, Halle (Saale), Germany
| | - Oliver Schweiger
- Department of Community Ecology, Helmholtz-Centre for Environmental Research-UFZ, Halle (Saale), Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
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5
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Gao R, Hu B, Yuan Y, He M, Wang R, Lou Y, Mu J. Nitrogen addition affects floral and vegetative traits, reproduction, and pollinator performance in Capsicum annuum L. ANNALS OF BOTANY 2023; 132:1131-1144. [PMID: 37638856 PMCID: PMC10809046 DOI: 10.1093/aob/mcad121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Accepted: 08/25/2023] [Indexed: 08/29/2023]
Abstract
BACKGROUND AND AIMS It has been demonstrated that nitrogen (N) addition alters flower morphology, floral rewards and pollinator performance. However, little is known about the effects of N addition on plant reproduction, including fruit set and seed set during selfing and outcrossing, floral and vegetative traits, and pollinator performance. We hypothesized that N addition would influence fruit set, seed set in selfed and outcrossed flowers, the relationship between vegetative and flower traits, and pollinator performance. METHODS A 2-year pot experiment was conducted in which Capsicum annuum was exposed to three levels of relatively short-term N supply, i.e. 0 g m-2 (no N addition, as a control), 4 g m-2 (4N) and 16 g m-2 (16N), which are equivalent to about 0-, 1- and 4-fold of the peak local N deposition. We measured flower rewards, flower morphology, flowering phenology, as well as pollinator visitation rate, fruit set and seed set by self- and outcross-fertilization of C. annuum. RESULTS The four levels of N addition increased plant biomass, biomass allocation to flowers, flower size, stigma-anther separation, nectar production and pollen production, resulting in an increase in pollinator visitation and fruit set. Nevertheless, the control and 16 levels of N addition reduced plant biomass, biomass allocation to flowers, flower size and stigma-anther separation, and nectar and pollen production, and consequently decreased pollinator visitation and fruit set. Exclusion of pollinators and hand-pollination experiments revealed that low levels of N addition were associated with high seed set in outcrossed flowers; however, this trend was reversed in flowers grown in the control and 16N treatments. CONCLUSION Our results suggest that an optimal level of 4N can enhance the correlation between flower traits, pollinator performance and plant reproduction. Our findings cast new light on the underlying mechanisms of plant-pollinator interactions and plant adaptation to nitrogen deposition.
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Affiliation(s)
- Rui Gao
- Ecological Security and Protection Key Laboratory of Sichuan Province, Mianyang Normal University, Mianyang 621000, China
| | - Baoshuang Hu
- Ecological Security and Protection Key Laboratory of Sichuan Province, Mianyang Normal University, Mianyang 621000, China
- College of Biological and Pharmaceutical Sciences, China Three Gorges University, Yichang 443002, China
| | - Yibin Yuan
- Chengdu Academy of Environmental Science, Chengdu, 610072, China
| | - Mengying He
- Ecological Security and Protection Key Laboratory of Sichuan Province, Mianyang Normal University, Mianyang 621000, China
| | - Ruolan Wang
- Ecological Security and Protection Key Laboratory of Sichuan Province, Mianyang Normal University, Mianyang 621000, China
| | - Yuanxin Lou
- Ecological Security and Protection Key Laboratory of Sichuan Province, Mianyang Normal University, Mianyang 621000, China
| | - Junpeng Mu
- Ecological Security and Protection Key Laboratory of Sichuan Province, Mianyang Normal University, Mianyang 621000, China
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Francis JS, Mueller TG, Vannette RL. Intraspecific variation in realized dispersal probability and host quality shape nectar microbiomes. THE NEW PHYTOLOGIST 2023; 240:1233-1245. [PMID: 37614102 DOI: 10.1111/nph.19195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 07/16/2023] [Indexed: 08/25/2023]
Abstract
Epiphytic microbes frequently affect plant phenotype and fitness, but their effects depend on microbe abundance and community composition. Filtering by plant traits and deterministic dispersal-mediated processes can affect microbiome assembly, yet their relative contribution to predictable variation in microbiome is poorly understood. We compared the effects of host-plant filtering and dispersal on nectar microbiome presence, abundance, and composition. We inoculated representative bacteria and yeast into 30 plants across four phenotypically distinct cultivars of Epilobium canum. We compared the growth of inoculated communities to openly visited flowers from a subset of the same plants. There was clear evidence of host selection when we inoculated flowers with synthetic communities. However, plants with the highest microbial densities when inoculated did not have the highest microbial densities when openly visited. Instead, plants predictably varied in the presence of bacteria, which was correlated with pollen receipt and floral traits, suggesting a role for deterministic dispersal. These findings suggest that host filtering could drive plant microbiome assembly in tissues where species pools are large and dispersal is high. However, deterministic differences in microbial dispersal to hosts may be equally or more important when microbes rely on an animal vector, dispersal is low, or arrival order is important.
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Affiliation(s)
- Jacob S Francis
- Department of Entomology and Nematology, University of California Davis, Davis, CA, 95616, USA
| | - Tobias G Mueller
- Department of Entomology, Cornell University, Ithaca, NY, 14853, USA
| | - Rachel L Vannette
- Department of Entomology and Nematology, University of California Davis, Davis, CA, 95616, USA
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Yessoufou K. The Patterns of Intraspecific Variations in Mass of Nectar Sugar along a Phylogeny Distinguish Native from Non-Native Plants in Urban Greenspaces in Southern England. PLANTS (BASEL, SWITZERLAND) 2023; 12:3270. [PMID: 37765434 PMCID: PMC10534836 DOI: 10.3390/plants12183270] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 09/09/2023] [Accepted: 09/12/2023] [Indexed: 09/29/2023]
Abstract
To serve human needs, non-native species are selected based on an array of functional traits, which generally confer competitive advantages to these species in their recipient environments. Identifying non-obvious functional traits that indirectly inform human selection of non-natives to introduce into urban greenspaces is not yet part of common discussions in invasion biology. We tested whether functional traits integrated within a phylogenetic framework, may reveal those subtle criteria underlying the introduction of non-native plants into urban greenspaces. We found no differences in terms of functional traits between natives and non-natives. We also found no evidence that functional traits predict nectar production, irrespective of how nectar production was measured. Finally, we found that the mean sugar concentration of nectar per flower is evolutionarily shared both within closely related non-native plants as well as within close native plants. However, phylogenetically close species share similar intraspecific variation in mass of nectar sugar per flower, but this is true only for non-native plants, thus revealing a non-obvious selection criteria of non-native plants for urban greenspaces. Our results indicate that the phylogenetic patterns of intraspecific variation in mass of nectar sugar per flower is the major criterion distinguishing non-natives from native plants in urban greenspaces in Southern England.
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Affiliation(s)
- Kowiyou Yessoufou
- Department of Geography, Environmental Management and Energy Studies, University of Johannesburg, P.O. Box 526, Auckland Park, Johannesburg 2006, South Africa
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8
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Wang X, Chen Y, Yi Y. Features of floral odor and nectar in the distylous Luculia pinceana (Rubiaceae) promote compatible pollination by hawkmoths. Ecol Evol 2023; 13:e9920. [PMID: 36969924 PMCID: PMC10030271 DOI: 10.1002/ece3.9920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 02/23/2023] [Accepted: 03/02/2023] [Indexed: 03/24/2023] Open
Abstract
It is hypothesized that in heterostylous plant species, standardization of signals of floral attraction between different morphs is advantageous, encouraging flower visitors to switch between morphs. It remains unclear whether signals of floral attraction (floral odor and properties of nectar) are similar between morphs in distylous species pollinated by hawkmoths, and how these relate to hawkmoth behavior. We observed the behavior of visitors to distylous Luculia pinceana (Rubiaceae), collected and analyzed floral odor, and examined properties of nectar (volume, sugar concentration, and composition) of long-styled and short-styled morphs during the day and night. Pollinator responses to the floral scent were tested with a Y-tube olfactometer. We conducted diurnal and nocturnal pollination treatments and six other pollination treatments to test the importance of nocturnal pollinators and to examine the self-incompatibility system. A species of hawkmoth, Cechenena lineosa, was the effective pollinator. The floral odor was rich in methyl benzoate, and sucrose was dominant in the nectar. There were no significant differences between the two morphs in the methyl benzoate content or the properties of nectar. Flowers released more methyl benzoate and secreted larger volumes of nectar with lower sugar concentration at night than during the day. The hawkmoth had a significant preference for methyl benzoate. Luculia pinceana was partially self-incompatible and relied on nocturnal pollinators for reproductive success. This study verifies that floral attraction signals are consistent between different morphs in this distylous species, promoting compatible pollination, and the features and the diel pattern of these signals between day and night are adapted to hawkmoth behavior.
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Affiliation(s)
- Xiaoyue Wang
- Key Laboratory of State Forestry Administration on Biodiversity Conservation in Karst Mountainous Areas of Southwestern ChinaGuizhou Normal UniversityGuiyangChina
- School of Life SciencesGuizhou Normal UniversityGuiyangChina
| | - Yan Chen
- Key Laboratory of State Forestry Administration on Biodiversity Conservation in Karst Mountainous Areas of Southwestern ChinaGuizhou Normal UniversityGuiyangChina
- School of Life SciencesGuizhou Normal UniversityGuiyangChina
| | - Yin Yi
- Key Laboratory of State Forestry Administration on Biodiversity Conservation in Karst Mountainous Areas of Southwestern ChinaGuizhou Normal UniversityGuiyangChina
- School of Life SciencesGuizhou Normal UniversityGuiyangChina
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9
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Su R, Dai W, Yang Y, Wang X, Gao R, He M, Zhao C, Mu J. Introduced honey bees increase host plant abundance but decrease native bumble bee species richness and abundance. Ecosphere 2022. [DOI: 10.1002/ecs2.4085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Ruijun Su
- Ecological Security and Protection Key Laboratory of Sichuan Province Mianyang Normal University Mianyang China
| | - Wenfei Dai
- Ecological Security and Protection Key Laboratory of Sichuan Province Mianyang Normal University Mianyang China
| | - Yulian Yang
- Ecological Security and Protection Key Laboratory of Sichuan Province Mianyang Normal University Mianyang China
| | - Xuelin Wang
- Ecological Security and Protection Key Laboratory of Sichuan Province Mianyang Normal University Mianyang China
| | - Rui Gao
- Ecological Security and Protection Key Laboratory of Sichuan Province Mianyang Normal University Mianyang China
| | - Mengying He
- Ecological Security and Protection Key Laboratory of Sichuan Province Mianyang Normal University Mianyang China
| | - Chuan Zhao
- Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization Chengdu Institute of Biology, Chinese Academy of Sciences Chengdu China
| | - Junpeng Mu
- Ecological Security and Protection Key Laboratory of Sichuan Province Mianyang Normal University Mianyang China
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10
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Wellington CN, Vaillancourt RE, Potts BM, Worledge D, O’Grady AP. Genetic Variation in Flowering Traits of Tasmanian Leptospermum scoparium and Association with Provenance Home Site Climatic Factors. PLANTS 2022; 11:plants11081029. [PMID: 35448758 PMCID: PMC9029099 DOI: 10.3390/plants11081029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 03/17/2022] [Accepted: 04/01/2022] [Indexed: 11/29/2022]
Abstract
Leptospermum scoparium is emerging as an economically important plant for the commercial production of mānuka honey and essential oils, both exhibiting unique antibacterial attributes. To support its domestication this is the first quantitative genetic study of variation for L. scoparium traits. It utilised plants from 200 open-pollinated families derived from 40 native populations, from across the species range in Tasmania, grown in a common garden field trial. The traits studied were survival, growth, and the flowering traits precocity, the timing of seasonal peak flowering, flowering duration, and flowering intensity. Significant genetic variation was evident at the population level for all traits studied and at the family level for three traits—growth, flowering precocity, and time to peak flowering. These three traits had moderate to high narrow-sense heritability estimates ranging from 0.27 to 0.69. For six of the traits studied, population differences were associated with climate attributes at the locations where seed was collected, suggesting adaptation to the local climate may have contributed to the observed population differentiation. Population level geographical trends suggest that genotypes to focus on for domestication originate from the eastern half of Tasmania for precociousness and the western half of Tasmania for earlier time to peak flowering and extended flowering duration.
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Affiliation(s)
- Christopher N. Wellington
- School of Biological Sciences, University of Tasmania, Hobart, TAS 7005, Australia; (R.E.V.); (B.M.P.)
- Correspondence: ; Tel.: +61-(0)476-998-376
| | - René E. Vaillancourt
- School of Biological Sciences, University of Tasmania, Hobart, TAS 7005, Australia; (R.E.V.); (B.M.P.)
| | - Brad M. Potts
- School of Biological Sciences, University of Tasmania, Hobart, TAS 7005, Australia; (R.E.V.); (B.M.P.)
| | - Dale Worledge
- CSIRO Land and Water, Hobart, TAS 7001, Australia; (D.W.); (A.P.O.)
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11
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Janeček Š, Chmel K, Ewome FL, Hrubá K, Klomberg Y, Kobe IN, Kouede RD, Mertens JEJ, Njie MM, Tropek R. Differences in Nectar Traits between Ornithophilous and Entomophilous Plants on Mount Cameroon. PLANTS (BASEL, SWITZERLAND) 2021; 10:1161. [PMID: 34200999 PMCID: PMC8226534 DOI: 10.3390/plants10061161] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Revised: 06/02/2021] [Accepted: 06/03/2021] [Indexed: 11/24/2022]
Abstract
Despite a growing number of studies, the role of pollinators as a selection agent for nectar traits remains unclear. Moreover, the lack of data from some biogeographic regions prohibits us from determining their general importance and global patterns. We analyzed nectar carbohydrate traits and determined the main pollinators of 66 plant species in the tropical forests of Mount Cameroon (tropical West Africa). The measured nectar traits included total sugar amounts and proportions of sucrose and hexoses (i.e., glucose and fructose). We report the nectar properties for plants visited by five pollinator groups (bees, butterflies, moths, hoverflies, and specialized birds). Our results indicate that, rather than specific evolution in each of the five plant groups, there was a unique nectar-trait evolution in plants pollinated by specialized birds. The ornithophilous plants had a higher proportion of sucrose and produced larger sugar amounts than the plants pollinated by insects. We also demonstrated a significant phylogenetic signal in the nectar properties in some lineages of the studied plants.
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Affiliation(s)
- Štěpán Janeček
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, CZ-128 44 Prague 2, Czech Republic; (K.C.); (Y.K.); (I.N.K.); (J.E.J.M.); (R.T.)
| | - Kryštof Chmel
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, CZ-128 44 Prague 2, Czech Republic; (K.C.); (Y.K.); (I.N.K.); (J.E.J.M.); (R.T.)
- Biology Centre, Czech Academy of Sciences, Branišovská 31, CZ-370 05 České Budějovice, Czech Republic;
| | | | - Karolína Hrubá
- Biology Centre, Czech Academy of Sciences, Branišovská 31, CZ-370 05 České Budějovice, Czech Republic;
- Department of Zoology, Faculty of Sciences, University of South Bohemia, Branišovská 1760, CZ-370 05 České Budějovice, Czech Republic
| | - Yannick Klomberg
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, CZ-128 44 Prague 2, Czech Republic; (K.C.); (Y.K.); (I.N.K.); (J.E.J.M.); (R.T.)
- Naturalis Biodiversity Center, Darwinweg 2, 2233 CR Leiden, The Netherlands
| | - Ishmeal N. Kobe
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, CZ-128 44 Prague 2, Czech Republic; (K.C.); (Y.K.); (I.N.K.); (J.E.J.M.); (R.T.)
| | - Raissa Dywou Kouede
- Department of Nursing, Faculty of Health Science, Herzing University, 1865 SR 436, Winter Park, Orlando, FL 32792, USA;
| | - Jan E. J. Mertens
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, CZ-128 44 Prague 2, Czech Republic; (K.C.); (Y.K.); (I.N.K.); (J.E.J.M.); (R.T.)
| | - Marcus Mokake Njie
- Department of Zoology and Animal Physiology, Faculty of Science, University of Buea, Buea 63, Cameroon;
| | - Robert Tropek
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, CZ-128 44 Prague 2, Czech Republic; (K.C.); (Y.K.); (I.N.K.); (J.E.J.M.); (R.T.)
- Biology Centre, Czech Academy of Sciences, Branišovská 31, CZ-370 05 České Budějovice, Czech Republic;
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12
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Bodó A, Farkas Á, Nagy DU, Rudolf K, Hoffmann R, Kocsis M, Morschhauser T. Soil Humus, Iron, Sulphate and Magnesium Content Affect Nectar Traits of Wild Garlic ( Allium ursinum L.). PLANTS (BASEL, SWITZERLAND) 2021; 10:plants10030597. [PMID: 33810174 PMCID: PMC8004594 DOI: 10.3390/plants10030597] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 03/12/2021] [Accepted: 03/17/2021] [Indexed: 06/12/2023]
Abstract
Recent studies revealed that from various ecological factors influencing nectar yield and quality of a plant, soil properties can be as important as microclimatic features. To date, few studies have investigated the relationship of soil characters to nectar traits of bee pollinated plants growing in natural associations. Our study intended to reveal which soil properties had the most powerful impact on nectar variables of wild garlic (Allium ursinum L.). Specimens were collected from fourteen habitats in two different years, and were potted in their original soil under the same climatic conditions. Nectar volumes and sugar concentrations were measured and soil samples were analysed for fourteen parameters. Statistical analyses revealed that the number of nectar producing Allium flowers, as well as the nectar volume and sugar content of nectar in individual flowers were influenced by both year and habitat. The humus, iron and sulphate content of soil showed negative correlation with the number of flowers producing nectar; total nectar volumes were negatively correlated with humus and iron content, but positively affected by magnesium content of the soil. Our results suggest that in addition to the effect of microclimatic factors, certain soil properties can have significant impact on nectar traits.
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Affiliation(s)
- Alexandra Bodó
- Institute of Biology, Faculty of Sciences, University of Pécs, 7624 Pécs, Hungary; (A.B.); (D.U.N.); (T.M.)
| | - Ágnes Farkas
- Department of Pharmacognosy, Faculty of Pharmacy, University of Pécs, 7624 Pécs, Hungary;
| | - Dávid U. Nagy
- Institute of Biology, Faculty of Sciences, University of Pécs, 7624 Pécs, Hungary; (A.B.); (D.U.N.); (T.M.)
| | - Kinga Rudolf
- Institute of Plant Production Science, Campus of Szent István, University of MATE, 7400 Kaposvár, Hungary; (K.R.); (R.H.)
| | - Richárd Hoffmann
- Institute of Plant Production Science, Campus of Szent István, University of MATE, 7400 Kaposvár, Hungary; (K.R.); (R.H.)
| | - Marianna Kocsis
- Institute of Biology, Faculty of Sciences, University of Pécs, 7624 Pécs, Hungary; (A.B.); (D.U.N.); (T.M.)
| | - Tamás Morschhauser
- Institute of Biology, Faculty of Sciences, University of Pécs, 7624 Pécs, Hungary; (A.B.); (D.U.N.); (T.M.)
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13
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The ecological consequences of herbivore-induced plant responses on plant-pollinator interactions. Emerg Top Life Sci 2020; 4:33-43. [PMID: 32537636 DOI: 10.1042/etls20190121] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 05/26/2020] [Accepted: 05/27/2020] [Indexed: 12/17/2022]
Abstract
Plant induced responses to herbivory have long been found to function as plant direct and indirect defenses and to be major drivers of herbivore community and population dynamics. While induced defenses are generally understood as cost-saving strategies that allow plants to allocate valuable resources into defense expression, it recently became clear that, in particular, induced metabolic changes can come with significant ecological costs. In particular, interactions with mutualist pollinators can be significantly compromised by herbivore-induced changes in floral morphology and metabolism. We review recent findings on the evidence for ecological conflict between defending against herbivores and attracting pollinators while using similar modes of information transfer (e.g. visual, olfactory, tactile). Specifically, we discuss plant traits and mechanisms through which plants mediate interactions between antagonists and mutualist and present functional hypotheses for how plants can overcome the resulting conflicts.
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14
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Dimorphic flowers modify the visitation order of pollinators from male to female flowers. Sci Rep 2020; 10:9965. [PMID: 32561882 PMCID: PMC7305190 DOI: 10.1038/s41598-020-66525-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Accepted: 05/21/2020] [Indexed: 12/11/2022] Open
Abstract
Sexual dimorphism is a pervasive form of variation within species. Understanding how and why sexual dimorphism evolves would contribute to elucidating the mechanisms underlying the diversification of traits. In flowering plants, pollinators are considered a driver of sexual dimorphism when they affect female and male plant fitness in distinct ways. Here, we found that flowers appear to manipulate the behavior of pollinators using sexually dimorphic traits in the dioecious tree Eurya japonica. In this plant, female flowers present a higher-quality reward for pollinators, whereas male flowers have a more conspicuous appearance. Plants benefit by inducing pollinators to carry pollen from male to female flowers, and their sexual dimorphism might thus facilitate pollen movement through pollinator behavior. In two-choice experiments, pollinators frequently moved from male to female flowers, whereas computer simulation suggested that sexually dimorphic traits would evolve if pollinators changed behavior depending on the traits of the flowers they had just visited. These results suggest that the floral traits affecting the visiting order of pollinators have evolved in plants. Using E. japonica, we theoretically show that the induction of sequential behavior in pollinators might be crucial to the evolution of sexual dimorphism in flowers, and our experiments support these findings.
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15
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Pyke GH, Kalman JRM, Bordin DM, Blanes L, Doble PA. Patterns of floral nectar standing crops allow plants to manipulate their pollinators. Sci Rep 2020; 10:1660. [PMID: 32015366 PMCID: PMC6997191 DOI: 10.1038/s41598-020-58102-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 01/03/2020] [Indexed: 12/02/2022] Open
Abstract
‘Pollination syndromes’ involving floral nectar have eluded satisfactory evolutionary explanation. For example, floral nectars for vertebrate-pollinated plants average low sugar concentrations, while such animals prefer high concentrations, perplexing pollination biologists and arousing recent controversy. Such relationships should result from evolutionary games, with plants and pollinators adopting Evolutionarily Stable Strategies, and nectar manipulating rather than attracting pollinators. Plant potential to manipulate pollinators depends on relationships between neighbouring flowers within plants, for all nectar attributes, but this has not been investigated. We measured nectar volume, concentration and sugar composition for open flowers on naturally-growing Blandfordia grandiflora plants, presenting classic bird-pollinated plant syndrome. To evaluate potential pollinator manipulation through nectar, we analysed relationships between neighbouring flowers for nectar volume, concentration, proportion sucrose, log(fructose/glucose), and sugar weight. To evaluate potential attraction of repeat-visits to flowers or plants through nectar, we compared attributes between successive days. Nearby flowers were positively correlated for all attributes, except log(fructose/glucose) as fructose≈glucose. Most relationships between nectar attributes for flowers and plants on successive days were non-significant. Nectar-feeding pollinators should therefore decide whether to visit another flower on a plant, based on all attributes of nectar just-obtained, enabling plants to manipulate pollinators through adjusting nectar. Plants are unlikely to attract repeat pollinator-visits through nectar production. Floral nectar evolution is conceptually straightforward but empirically challenging. A mutant plant deviating from the population in attributes of nectar-production per flower would manipulate, rather than attract, nectar-feeding pollinators, altering pollen transfer, hence reproduction. However, links between floral nectar and plant fitness present empirical difficulties.
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Affiliation(s)
- Graham H Pyke
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, CN, 650201, Kunming, PR China. .,Department of Biological Sciences, Macquarie University, Ryde, NSW, 2109, Australia.
| | - John R M Kalman
- School of Mathematical & Physical Sciences, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - Dayanne M Bordin
- School of Mathematical & Physical Sciences, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - Lucas Blanes
- School of Mathematical & Physical Sciences, University of Technology Sydney, Ultimo, NSW, 2007, Australia.,Laboratory for Applied Science and Technology in Health, Carlos Chagas Institute, Oswaldo Cruz Foundation (Fiocruz), Curitiba, Brazil
| | - Philip A Doble
- School of Mathematical & Physical Sciences, University of Technology Sydney, Ultimo, NSW, 2007, Australia
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16
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Parachnowitsch AL, Manson JS, Sletvold N. Evolutionary ecology of nectar. ANNALS OF BOTANY 2019; 123:247-261. [PMID: 30032269 PMCID: PMC6344224 DOI: 10.1093/aob/mcy132] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Accepted: 06/16/2018] [Indexed: 05/24/2023]
Abstract
Background Floral nectar is an important determinant of plant-pollinator interactions and an integral component of pollination syndromes, suggesting it is under pollinator-mediated selection. However, compared to floral display traits, we know little about the evolutionary ecology of nectar. Combining a literature review with a meta-analysis approach, we summarize the evidence for heritable variation in nectar traits and link this variation to pollinator response and plant fitness. We further review associations between nectar traits and floral signals and discuss them in the context of honest signalling and targets of selection. Scope Although nectar is strongly influenced by environmental factors, heritable variation in nectar production rate has been documented in several populations (mean h2 = 0.31). Almost nothing is known about heritability of other nectar traits, such as sugar and amino acid concentrations. Only a handful of studies have quantified selection on nectar traits, and few find statistically significant selection. Pollinator responses to nectar traits indicate they may drive selection, but studies tying pollinator preferences to plant fitness are lacking. So far, only one study conclusively identified pollinators as selective agents on a nectar trait, and the role of microbes, herbivores, nectar robbers and abiotic factors in nectar evolution is largely hypothetical. Finally, there is a trend for positive correlations among floral cues and nectar traits, indicating honest signalling of rewards. Conclusions Important progress can be made by studies that quantify current selection on nectar in natural populations, as well as experimental approaches that identify the target traits and selective agents involved. Signal-reward associations suggest that correlational selection may shape evolution of nectar traits, and studies exploring these more complex forms of natural selection are needed. Many questions about nectar evolution remain unanswered, making this a field ripe for future research.
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Affiliation(s)
- Amy L Parachnowitsch
- Plant Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
- Department of Biology, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - Jessamyn S Manson
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Nina Sletvold
- Plant Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
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17
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Opedal ØH. The evolvability of animal-pollinated flowers: towards predicting adaptation to novel pollinator communities. THE NEW PHYTOLOGIST 2019; 221:1128-1135. [PMID: 30145801 DOI: 10.1111/nph.15403] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 07/23/2018] [Indexed: 06/08/2023]
Abstract
In the event of a community turnover, population decline, or complete disappearance of pollinators, animal-pollinated plants may respond by adapting to novel pollinators or by changing their mating system. The ability of populations to adapt is determined by their ability to respond to novel selection pressures, i.e. their evolvability. In the short term, evolvability is determined by standing genetic variation in the trait under selection. To evaluate the evolutionary potential of plant reproductive systems, I compiled genetic-variance estimates for a large selection of floral traits mediating shifts in pollination and mating systems. Then, I computed evolvabilities and compared these among trait groups and against the evolvabilities of vegetative traits. Evolvabilities of most floral traits were substantial yet tended to be lower than the median for vegetative traits. Among floral traits, herkogamy (anther-stigma distance), floral-display traits and perhaps floral-volatile concentrations had greater-than-average evolvabilities, while the evolvabilities of pollinator-fit traits were below average. These results suggest that most floral traits have the potential to evolve rapidly in response to novel selection pressures, providing resilience of plant reproductive systems in the event of changing pollinator communities.
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Affiliation(s)
- Øystein H Opedal
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, NTNU, Trondheim, 7491, Norway
- Research Centre for Ecological Change, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
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18
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Palmer-Young EC, Farrell IW, Adler LS, Milano NJ, Egan PA, Junker RR, Irwin RE, Stevenson PC. Chemistry of floral rewards: intra- and interspecific variability of nectar and pollen secondary metabolites across taxa. ECOL MONOGR 2018. [DOI: 10.1002/ecm.1335] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Evan C. Palmer-Young
- Department of Biology; University of Massachusetts at Amherst; Amherst Massachusetts 01003 USA
| | - Iain W. Farrell
- Royal Botanic Gardens, Kew; Richmond Surrey TW9 3AB United Kingdom
| | - Lynn S. Adler
- Department of Biology; University of Massachusetts at Amherst; Amherst Massachusetts 01003 USA
| | - Nelson J. Milano
- Department of Biology; University of Massachusetts at Amherst; Amherst Massachusetts 01003 USA
| | - Paul A. Egan
- Department of Plant Protection Biology; Swedish University of Agricultural Sciences; SE-23053 Alnarp Sweden
| | - Robert R. Junker
- Department of Bioscience; University of Salzburg; Hellbrunnerstrasse 34 5020 Salzburg Austria
| | - Rebecca E. Irwin
- Department of Applied Ecology; North Carolina State University; Raleigh North Carolina 27695 USA
| | - Philip C. Stevenson
- Royal Botanic Gardens, Kew; Richmond Surrey TW9 3AB United Kingdom
- University of Greenwich; Medway ME4 4 TB United Kingdom
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19
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Egan PA, Adler LS, Irwin RE, Farrell IW, Palmer-Young EC, Stevenson PC. Crop Domestication Alters Floral Reward Chemistry With Potential Consequences for Pollinator Health. FRONTIERS IN PLANT SCIENCE 2018; 9:1357. [PMID: 30319666 PMCID: PMC6169423 DOI: 10.3389/fpls.2018.01357] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 08/28/2018] [Indexed: 05/29/2023]
Abstract
Crop domestication can lead to weakened expression of plant defences, with repercussions for herbivore and pathogen susceptibility. However, little is known about how domestication alters traits that mediate other important ecological interactions in crops, such as pollination. Secondary metabolites, which underpin many defence responses in plants, also occur widely in nectar and pollen and influence plant-pollinator interactions. Thus, domestication may also affect secondary compounds in floral rewards, with potential consequences for pollinators. To test this hypothesis, we chemically analysed nectar and pollen from wild and cultivated plants of highbush blueberry (Vaccinium corymbosum L.), before conducting an artificial diet bioassay to examine pollinator-pathogen interactions. Our results indicated that domestication has significantly altered the chemical composition of V. corymbosum nectar and pollen, and reduced pollen chemical diversity in cultivated plants. Of 20 plant metabolites identified in floral rewards, 13 differed significantly between wild and cultivated plants, with a majority showing positive associations with wild compared to cultivated plants. These included the amino acid phenylalanine (4.5 times higher in wild nectar, 11 times higher in wild pollen), a known bee phagostimulant and essential nutrient; and the antimicrobial caffeic acid ester 4-O-caffeoylshikimic acid (two times higher in wild nectar). We assessed the possible biological relevance of variation in caffeic acid esters in bioassays, using the commercially available 3-O-caffeoylquinic acid. This compound reduced Bombus impatiens infection by a prominent gut pathogen (Crithidia) at concentrations that occurred in wild but not cultivated plants, suggesting that domestication may influence floral traits with consequences for bee health. Appreciable levels of genetic variation and heritability were found for most floral reward chemical traits, indicating good potential for selective breeding. Our study provides the first assessment of plant domestication effects on floral reward chemistry and its potential repercussions for pollinator health. Given the central importance of pollinators for agriculture, we discuss the need to extend such investigations to pollinator-dependent crops more generally and elaborate on future research directions to ascertain wider trends, consequences for pollinators, mechanisms, and breeding solutions.
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Affiliation(s)
- Paul A. Egan
- Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - Lynn S. Adler
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, United States
| | - Rebecca E. Irwin
- Department of Applied Ecology, North Carolina State University, Raleigh, NC, United States
| | | | - Evan C. Palmer-Young
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, United States
| | - Philip C. Stevenson
- Royal Botanic Gardens, Kew, Richmond, United Kingdom
- Natural Resources Institute, University of Greenwich, London, United Kingdom
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20
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Vannette RL, Fukami T. Contrasting effects of yeasts and bacteria on floral nectar traits. ANNALS OF BOTANY 2018; 121:1343-1349. [PMID: 29562323 PMCID: PMC6007235 DOI: 10.1093/aob/mcy032] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 02/20/2018] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND AIMS Flowers can be highly variable in nectar volume and chemical composition, even within the same plant, but the causes of this variation are not fully understood. One potential cause is nectar-colonizing bacteria and yeasts, but experimental tests isolating their effects on wildflowers are largely lacking. This study examines the effects of dominant species of yeasts and bacteria on the hummingbird-pollinated shrub, Mimulus aurantiacus, in California. METHODS Wildflowers were inoculated with field-relevant titres of either the yeast Metschnikowia reukaufii or the bacterium Neokomagataea sp. (formerly Gluconobacter sp.), both isolated from M. aurantiacus nectar. Newly opened flowers were bagged, inoculated, harvested after 3 d and analysed for microbial abundance, nectar volume, and sugar and amino acid concentration and composition. KEY RESULTS Yeast inoculation reduced amino acid concentration and altered amino acid composition, but had no significant effect on nectar volume or sugar composition. In contrast, bacterial inoculation increased amino acid concentration, enhanced the proportion of nectar sugars comprised by monosaccharides, and reduced nectar volume. CONCLUSIONS The results presented suggest that microbial inhabitants of floral nectar can make nectar characteristics variable among flowers through divergent effects of yeasts and bacteria on nectar chemistry and availability, probably modifying plant-pollinator interactions.
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Affiliation(s)
- Rachel L Vannette
- Department of Biology, Stanford University, Stanford, CA, USA
- Department of Entomology and Nematology, University of California Davis, Davis, CA, USA
| | - Tadashi Fukami
- Department of Biology, Stanford University, Stanford, CA, USA
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21
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Clearwater MJ, Revell M, Noe S, Manley-Harris M. Influence of genotype, floral stage, and water stress on floral nectar yield and composition of mānuka (Leptospermum scoparium). ANNALS OF BOTANY 2018; 121:501-512. [PMID: 29300875 PMCID: PMC5838834 DOI: 10.1093/aob/mcx183] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 11/27/2017] [Indexed: 05/27/2023]
Abstract
Background and Aims Floral nectar can be variable in composition, influencing pollinator behaviour and the composition of honey derived from it. The non-peroxide antibacterial activity of mānuka (Leptospermum scoparium, Myrtaceae) honey results from the chemical conversion of the triose sugar dihydroxyacetone (DHA), after DHA accumulates for an unknown reason in the nectar. This study examined variation in nectar DHA, glucose, fructose and sucrose content with floral stage of development, between mānuka genotypes with differing flower morphology, and in response to water stress. Methods Six mānuka genotypes were grown without nectar-feeding insects. Stages of flower development were defined, nectar was harvested and its composition was compared between stages and genotypes, and with floral morphology. Water stress was imposed and its effect on nectar composition was examined. Key Results Nectar was present from soon after flower opening until the end of petal abscission, with the quantity of accumulated nectar sugars rising, then stabilizing or falling, indicating nectar secretion followed by reabsorption in some genotypes. The quantity of DHA, the ratio of DHA to other nectar sugars and the fructose to glucose ratio also varied with stage of development, indicating differences in rates of production and reabsorption between nectar components. Nectar composition and yield per flower also differed between genotypes, although neither was positively related to nectary area or stomatal density. Drying soil had no effect on nectar composition or yield, but variation in nectar yield was correlated with temperature prior to nectar sampling. Conclusions Mānuka nectar yield and composition are strongly influenced by plant genotype, flower age and the environment. There were clear stoichiometric relationships between glucose, fructose and sucrose per flower, but DHA per flower was only weakly correlated with the amount of other sugars, suggesting that accumulation of the triose sugar is indirectly coupled to secretion of the larger sugars by the nectary parenchyma.
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Affiliation(s)
| | - Maria Revell
- School of Science, University of Waikato, Hamilton, New Zealand
| | - Stevie Noe
- School of Science, University of Waikato, Hamilton, New Zealand
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22
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Varga S, Soulsbury CD. Sexually-trimorphic interactions with colour polymorphism determine nectar quality in a herbaceous perennial. Sci Rep 2017; 7:45838. [PMID: 28374829 PMCID: PMC5379179 DOI: 10.1038/srep45838] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 03/06/2017] [Indexed: 11/09/2022] Open
Abstract
Amongst gynodioecious plant breeding systems, there can exist intermediate morphs with a reduction in their male function (i.e. reduced number of functional anthers). Along with this sexual trimorphism, plants can also show floral colour polymorphism. Such intricate mixtures of phenotypes within a species may have complex effects on floral rewards. Floral rewards are known to vary between sexually dimorphic species and to a lesser extent between colour morphs. However, the interactive effect of sexual trimorphism and colour polymorphism is unexplored. We measured nectar's sugar content in the sexually trimorphic Geranium sylvaticum, a gynodioecious plant with a light/dark floral polymorphism. We found that nectar reward differed across genders and colour morphs. Results were not however consistent within the three genders; dark female and hermaphrodite flowers had higher sugar content than light morphs, whereas intermediate flowers did not. As expected, females and hermaphrodites had different nectar reward, with intermediate morphs being midway between the other genders. In intermediates, the sugar content was not related to the number of functional stamens. We show for the first time the existence of sex-specific differences between flower gender and colour morphs in nectar rewards. Our results demonstrate the importance of considering multiple and conflicting selection pressures to explain rewards.
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Affiliation(s)
- Sandra Varga
- School of Life Sciences, University of Lincoln, Joseph Banks Laboratories, Lincoln LN6 7TS, UK
| | - Carl D. Soulsbury
- School of Life Sciences, University of Lincoln, Joseph Banks Laboratories, Lincoln LN6 7TS, UK
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Lange D, Calixto ES, Del-Claro K. Variation in Extrafloral Nectary Productivity Influences the Ant Foraging. PLoS One 2017; 12:e0169492. [PMID: 28046069 PMCID: PMC5207748 DOI: 10.1371/journal.pone.0169492] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 12/16/2016] [Indexed: 11/30/2022] Open
Abstract
Extrafloral nectar is the main food source offered by plants to predatory ants in most land environments. Although many studies have demonstrated the importance of extrafloral nectaries (EFNs) to plant defense against herbivores, the influence of EFNs secretory activity pattern on predatory ants remains yet not fully understood. Here, we verified the relation between the extrafloral nectar production of a plant community in Cerrado in different times of the day, and its attractiveness to ants. The extrafloral nectaries (EFNs) of seven plant species showed higher productivity overnight. Ant abundance was higher in times of large extrafloral nectar production, however, there was no positive relation between ant richness on plants and EFNs productivity. There was temporal resource partitioning among ant species, and it indicates strong resource competition. The nectar productivity varied among plant species and time of the day, and it influenced the visitation patterns of ants. Therefore, EFNs are a key ant-plant interaction driver in the studied system.
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Affiliation(s)
- Denise Lange
- Universidade Tecnológica Federal do Paraná, Campus Santa Helena, Santa Helena, PR, Brazil
| | - Eduardo Soares Calixto
- Pós-Graduação em Entomologia, Faculdade de Filosofia, Ciências e Letras, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Kleber Del-Claro
- Laboratório de Ecologia Comportamental e de Interações (LECI), Instituto de Biologia, Universidade Federal de Uberlândia, Uberlândia, MG, Brazil
- * E-mail:
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24
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Milano ER, Kenney AM, Juenger TE. Adaptive differentiation in floral traits in the presence of high gene flow in scarlet gilia (
Ipomopsis aggregata
). Mol Ecol 2016; 25:5862-5875. [DOI: 10.1111/mec.13752] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 06/20/2016] [Accepted: 06/22/2016] [Indexed: 10/21/2022]
Affiliation(s)
- Elizabeth R. Milano
- Department of Integrative Biology The University of Texas at Austin 1 University Station C0930 Austin TX 78712 USA
| | - Amanda M. Kenney
- Department of Biological Sciences St. Edward's University 3001 S. Congress Ave. Austin TX 78704 USA
| | - Thomas E. Juenger
- Department of Integrative Biology The University of Texas at Austin 1 University Station C0930 Austin TX 78712 USA
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25
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Nakamura S, Kudo G. Foraging responses of bumble bees to rewardless floral patches: importance of within-plant variance in nectar presentation. AOB PLANTS 2016; 8:plw037. [PMID: 27178064 PMCID: PMC4940503 DOI: 10.1093/aobpla/plw037] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 05/07/2016] [Indexed: 06/01/2023]
Abstract
Spatiotemporal variation in nectar distribution is a key factor affecting pollinator movements between flowers and plants within a population. Pollinators having systematic searching ability can flexibly respond to the reward condition of floral patches, and they tend to revisit rewarding patches. However, foraging behaviour may be influenced by the nectar distribution within populations. To evaluate the effects of unrewarding experiences and plant distribution, we compared bumble bee foraging behaviours between naturally rewarding and artificially rewardless (by nectary removal) patches in two aconite populations with different plant densities. Visitation frequency to the patches, number of successive flower visits within inflorescences, and successive inflorescence visits within patches were recorded. Nectar production and standing crop were also measured. Bumble bees increased the movements between neighbouring inflorescences instead of leaving the patches when they faced rewardless flowers. A large variance in nectar production existed among flowers within plants. This might explain the observed bumble bee behaviour, because they could be rewarded by moving to the adjacent inflorescences even after a rewardless experience. Our results imply that a highly variable nectar reward in a population might mask the disadvantage of completely rewardless individuals.
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Affiliation(s)
- Shoko Nakamura
- Graduate School of Environmental Science, Hokkaido University, Kita-ku N10 W5, Sapporo, Hokkaido, 060-0810, Japan
| | - Gaku Kudo
- Faculty of Environmental Earth Science, Hokkaido University, Kita-ku N10 W5, Sapporo, Hokkaido, 060-0810, Japan
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26
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Bertazzini M, Forlani G. Intraspecific Variability of Floral Nectar Volume and Composition in Rapeseed (Brassica napus L. var. oleifera). FRONTIERS IN PLANT SCIENCE 2016; 7:288. [PMID: 27014311 PMCID: PMC4792878 DOI: 10.3389/fpls.2016.00288] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Accepted: 02/23/2016] [Indexed: 05/08/2023]
Abstract
Numerous angiosperms rely on pollinators to ensure efficient flower fertilization, offering a reward consisting of nourishing nectars produced by specialized floral cells, known as nectaries. Nectar components are believed to derive from phloem sap that is enzymatically processed and transformed within nectaries. An increasing body of evidence suggests that nectar composition, mainly amino acids, may influence pollinator attraction and fidelity. This notwithstanding, little is known about the range of natural variability in nectar content for crop species. Sugar and amino acid composition of nectar harvested from field-grown plants at the 63-65 phenological stage was determined for a set of 44 winter genotypes of rapeseed, a bee-pollinated crop. Significant differences were found for solute concentrations, and an even higher variability was evident for nectar volumes, resulting in striking differences when results were expressed on a single flower basis. The comparison of nectar and phloem sap from a subset of eight varieties pointed out qualitative and quantitative diversities with respect to both sugars and amino acids. Notably, amino acid concentration in phloem sap was up to 100 times higher than in nectar. Phloem sap showed a much more uniform composition, suggesting that nectar variability depends mainly on nectary metabolism. A better understanding of the basis of nectar production would allow an improvement of seed set efficiency, as well as hive management and honey production.
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27
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Schaeffer RN, Vannette RL, Irwin RE. Nectar yeasts in Delphinium nuttallianum (Ranunculaceae) and their effects on nectar quality. FUNGAL ECOL 2015. [DOI: 10.1016/j.funeco.2015.09.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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28
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Nogueira A, Rey PJ, Alcántara JM, Feitosa RM, Lohmann LG. Geographic mosaic of plant evolution: extrafloral nectary variation mediated by ant and herbivore assemblages. PLoS One 2015; 10:e0123806. [PMID: 25885221 PMCID: PMC4401756 DOI: 10.1371/journal.pone.0123806] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2014] [Accepted: 03/06/2015] [Indexed: 11/18/2022] Open
Abstract
Herbivory is an ecological process that is known to generate different patterns of selection on defensive plant traits across populations. Studies on this topic could greatly benefit from the general framework of the Geographic Mosaic Theory of Coevolution (GMT). Here, we hypothesize that herbivory represents a strong pressure for extrafloral nectary (EFN) bearing plants, with differences in herbivore and ant visitor assemblages leading to different evolutionary pressures among localities and ultimately to differences in EFN abundance and function. In this study, we investigate this hypothesis by analyzing 10 populations of Anemopaegma album (30 individuals per population) distributed through ca. 600 km of Neotropical savanna and covering most of the geographic range of this plant species. A common garden experiment revealed a phenotypic differentiation in EFN abundance, in which field and experimental plants showed a similar pattern of EFN variation among populations. We also did not find significant correlations between EFN traits and ant abundance, herbivory and plant performance across localities. Instead, a more complex pattern of ant–EFN variation, a geographic mosaic, emerged throughout the geographical range of A. album. We modeled the functional relationship between EFNs and ant traits across ant species and extended this phenotypic interface to characterize local situations of phenotypic matching and mismatching at the population level. Two distinct types of phenotypic matching emerged throughout populations: (1) a population with smaller ants (Crematogaster crinosa) matched with low abundance of EFNs; and (2) seven populations with bigger ants (Camponotus species) matched with higher EFN abundances. Three matched populations showed the highest plant performance and narrower variance of EFN abundance, representing potential plant evolutionary hotspots. Cases of mismatched and matched populations with the lowest performance were associated with abundant and highly detrimental herbivores. Our findings provide insights on the ecology and evolution of plant–ant guarding systems, and suggest new directions to research on facultative mutualistic interactions at wide geographic scales.
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Affiliation(s)
- Anselmo Nogueira
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo, São Paulo, Brazil
- * E-mail: (AN); (PJR); (JMA); (RMF); (LGL)
| | - Pedro J. Rey
- Departamento de Biología Animal, Biología Vegetal y Ecología, Facultad de Ciencias Experimentales, Universidad de Jaén, Jaén, Andalucia, Spain
- * E-mail: (AN); (PJR); (JMA); (RMF); (LGL)
| | - Julio M. Alcántara
- Departamento de Biología Animal, Biología Vegetal y Ecología, Facultad de Ciencias Experimentales, Universidad de Jaén, Jaén, Andalucia, Spain
- * E-mail: (AN); (PJR); (JMA); (RMF); (LGL)
| | - Rodrigo M. Feitosa
- Departamento de Zoologia, Setor de Ciências Biológicas, Universidade Federal do Paraná, Curitiba, Paraná, Brazil
- * E-mail: (AN); (PJR); (JMA); (RMF); (LGL)
| | - Lúcia G. Lohmann
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo, São Paulo, Brazil
- * E-mail: (AN); (PJR); (JMA); (RMF); (LGL)
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29
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Samuni-Blank M, Izhaki I, Laviad S, Bar-Massada A, Gerchman Y, Halpern M. The role of abiotic environmental conditions and herbivory in shaping bacterial community composition in floral nectar. PLoS One 2014; 9:e99107. [PMID: 24922317 PMCID: PMC4055640 DOI: 10.1371/journal.pone.0099107] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 05/09/2014] [Indexed: 01/26/2023] Open
Abstract
Identifying the processes that drive community assembly has long been a central theme in ecology. For microorganisms, a traditional prevailing hypothesis states that “everything is everywhere, but the environment selects”. Although the bacterial community in floral nectar may be affected by both atmosphere (air-borne bacteria) and animals as dispersal vectors, the environmental and geographic factors that shape microbial communities in floral nectar are unknown. We studied culturable bacterial communities in Asphodelus aestivus floral nectar and in its typical herbivorous bug Capsodes infuscatus, along an aridity gradient. Bacteria were sampled from floral nectar and bugs at four sites, spanning a geographical range of 200 km from Mediterranean to semi-arid conditions, under open and bagged flower treatments. In agreement with the niche assembly hypothesis, the differences in bacterial community compositions were explained by differences in abiotic environmental conditions. These results suggest that microbial model systems are useful for addressing macro-ecological questions. In addition, similar bacterial communities were found in the nectar and on the surface of the bugs that were documented visiting the flowers. These similarities imply that floral nectar bacteria dispersal is shaped not only by air borne bacteria and nectar consumers as previously reported, but also by visiting vectors like the mirid bugs.
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Affiliation(s)
- Michal Samuni-Blank
- Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Mount Carmel, Haifa, Israel
| | - Ido Izhaki
- Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Mount Carmel, Haifa, Israel
| | - Sivan Laviad
- Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Mount Carmel, Haifa, Israel
| | - Avi Bar-Massada
- Department of Biology and Environment, University of Haifa at Oranim, Oranim, Tivon, Israel
| | - Yoram Gerchman
- Department of Biology and Environment, University of Haifa at Oranim, Oranim, Tivon, Israel
| | - Malka Halpern
- Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa, Mount Carmel, Haifa, Israel
- Department of Biology and Environment, University of Haifa at Oranim, Oranim, Tivon, Israel
- * E-mail:
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30
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Renoult JP, Valido A, Jordano P, Schaefer HM. Adaptation of flower and fruit colours to multiple, distinct mutualists. THE NEW PHYTOLOGIST 2014; 201:678-686. [PMID: 26012880 DOI: 10.1111/nph.12539] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 08/29/2013] [Indexed: 05/27/2023]
Abstract
Communication in plant-animal mutualisms frequently involves multiple perceivers. A fundamental uncertainty is whether and how species adapt to communicate with groups of mutualists having distinct sensory abilities. We quantified the colour conspicuousness of flowers and fruits originating from one European and two South American plant communities, using visual models of pollinators (bee and fly) and seed dispersers (bird, primate and marten). We show that flowers are more conspicuous than fruits to pollinators, and the reverse to seed dispersers. In addition, flowers are more conspicuous to pollinators than to seed dispersers and the reverse for fruits. Thus, despite marked differences in the visual systems of mutualists, flower and fruit colours have evolved to attract multiple, distinct mutualists but not unintended perceivers. We show that this adaptation is facilitated by a limited correlation between flower and fruit colours, and by the fact that colour signals as coded at the photoreceptor level are more similar within than between functional groups (pollinators and seed dispersers). Overall, these results provide the first quantitative demonstration that flower and fruit colours are adaptations allowing plants to communicate simultaneously with distinct groups of mutualists.
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Affiliation(s)
- Julien P Renoult
- Department of Evolutionary Biology and Animal Ecology, Faculty of Biology, University of Freiburg, Hauptstrasse 1, 79104, Freiburg, Germany
| | - Alfredo Valido
- Integrative Ecology Group, Estación Biológica de Doñana (EBD-CSIC), C/Américo Vespucio s/n, Isla de La Cartuja, Sevilla, E-41092, Spain
| | - Pedro Jordano
- Integrative Ecology Group, Estación Biológica de Doñana (EBD-CSIC), C/Américo Vespucio s/n, Isla de La Cartuja, Sevilla, E-41092, Spain
| | - H Martin Schaefer
- Department of Evolutionary Biology and Animal Ecology, Faculty of Biology, University of Freiburg, Hauptstrasse 1, 79104, Freiburg, Germany
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31
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Petry WK, Perry KI, Fremgen A, Rudeen SK, Lopez M, Dryburgh J, Mooney KA. Mechanisms underlying plant sexual dimorphism in multi-trophic arthropod communities. Ecology 2013; 94:2055-65. [PMID: 24279276 DOI: 10.1890/12-2170.1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A growing body of research documents the importance of plant genetic effects on arthropod community structure. However, the mechanisms underlying these effects are often unclear. Additionally, plant genetic effects have largely been quantified in common gardens, thus inflating the estimates of their importance by minimizing levels of natural variation. Using Valeriana edulis, a dioecious plant with genetically based sex determination, we conducted surveys and experiments on wild-grown individuals to document field patterns of arthropod association between the sexes and the mechanisms underlying these plant genetic effects. Three years of surveys revealed strong and consistent sex-biased arthropod association in wild-grown plants: female plants supported 4-fold, 1.5-fold, and 4-fold higher densities of aphids, aphid predators, and aphid-tending ants, respectively, compared to males. There was mixed evidence that the female bias for aphids was due to higher plant quality, while we found no difference between plant sexes in aphid preference or the top-down effects of predators and tending ants. Female bias for ants was due to both the greater attractiveness of female plants (direct effect mediated by floral nectar) and an independent, weaker effect of higher aphid abundance on females (density-mediated indirect effect). Conversely, the female bias for predators was driven solely by the greater attractiveness of female plants. We did not find interaction modification, i.e., ant-aphid and predator-aphid interactions were equivalent between plant sexes. Plant sex explained 0.24%, 2.28%, and 4.42% of the variance in aphids, predators, and ants, respectively, values comparable to but slightly weaker than those previously reported from common-garden studies. In contrast to the prediction of diminished plant genetic effects with increasing trophic level, we show how weak indirect effects on predators and parasitoids (via herbivores) can be complemented by strong direct effects via common plant traits (floral resources). In summary, we document direct and indirect effects of genetically based sex on a multi-trophic arthropod community that were expressed in wild-grown plants across multiple years.
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Affiliation(s)
- William K Petry
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92697-2525, USA.
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32
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Varga S, Nuortila C, Kytöviita MM. Nectar sugar production across floral phases in the Gynodioecious Protandrous Plant Geranium sylvaticum [corrected]. PLoS One 2013; 8:e62575. [PMID: 23614053 PMCID: PMC3632553 DOI: 10.1371/journal.pone.0062575] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 03/23/2013] [Indexed: 12/02/2022] Open
Abstract
Many zoophilous plants attract their pollinators by offering nectar as a reward. In gynodioecious plants (i.e. populations are composed of female and hermaphrodite individuals) nectar production has been repeatedly reported to be larger in hermaphrodite compared to female flowers even though nectar production across the different floral phases in dichogamous plants (i.e. plants with time separation of pollen dispersal and stigma receptivity) has rarely been examined. In this study, sugar production in nectar standing crop and secretion rate were investigated in Geranium sylvaticum, a gynodioecious plant species with protandry (i.e. with hermaphrodite flowers releasing their pollen before the stigma is receptive). We found that flowers from hermaphrodites produced more nectar than female flowers in terms of total nectar sugar content. In addition, differences in nectar production among floral phases were found in hermaphrodite flowers but not in female flowers. In hermaphrodite flowers, maximum sugar content coincided with pollen presentation and declined slightly towards the female phase, indicating nectar reabsorption, whereas in female flowers sugar content did not differ between the floral phases. These differences in floral reward are discussed in relation to visitation patterns by pollinators and seed production in this species.
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Affiliation(s)
- Sandra Varga
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland.
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33
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Parachnowitsch AL, Burdon RCF, Raguso RA, Kessler A. Natural selection on floral volatile production in Penstemon digitalis: highlighting the role of linalool. PLANT SIGNALING & BEHAVIOR 2013; 8:e22704. [PMID: 23221753 PMCID: PMC3745574 DOI: 10.4161/psb.22704] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 10/29/2012] [Accepted: 10/29/2012] [Indexed: 05/29/2023]
Abstract
Natural selection is thought to have shaped the evolution of floral scent; however, unlike other floral characters, we have a rudimentary knowledge of how phenotypic selection acts on scent. We found that floral scent was under stronger selection than corolla traits such as flower size and flower color in weakly scented Penstemon digitalis. Our results suggest that to understand evolution in floral phenotypes, including scent in floral selection, studies are crucial. For P. digitalis, linalool was the direct target of selection in the scent bouquet. Therefore, we determined the enantiomeric configuration of linalool because interacting insects may perceive the enantiomers differentially. We found that P. digitalis produces only (S)-(+)-linalool and, more interestingly, it is also taken up into the nectar. Because the nectar is scented and flavored with (S)-(+)-linalool, it may be an important cue for pollinators visiting P. digitalis flowers.
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Affiliation(s)
- Amy L. Parachnowitsch
- Plant Ecology and Evolution; Evolutionary Biology Centre; Uppsala University; Uppsala, Sweden
| | - Rosalie C. F. Burdon
- Plant Ecology and Evolution; Evolutionary Biology Centre; Uppsala University; Uppsala, Sweden
| | - Robert A. Raguso
- Department of Neurobiology and Behavior; Cornell University; Ithaca, NY USA
| | - André Kessler
- Department of Ecology and Evolutionary Biology; Cornell University; Ithaca, NY USA
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34
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Carlson JE, Holsinger KE. Direct and indirect selection on floral pigmentation by pollinators and seed predators in a color polymorphic South African shrub. Oecologia 2012; 171:905-19. [PMID: 23007806 DOI: 10.1007/s00442-012-2453-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 08/24/2012] [Indexed: 12/30/2022]
Abstract
The coexistence of different color morphs is often attributed to variable selection pressures across space, time, morph frequencies, or selection agents, but the routes by which each morph is favored are rarely identified. In this study we investigated factors that influence floral color polymorphisms on a local scale in Protea, within which approximately 40% of species are polymorphic. Previous work shows that seed predators and reproductive differences likely contribute to maintaining polymorphism in four Protea species. We explored whether selection acts directly or indirectly on floral color in two populations of Protea aurea, using path analysis of pollinator behavior, nectar production, seed predation, color, morphology, and maternal fecundity fitness components. We found that avian pollinators spent more time on white morphs, likely due to nectar differences, but that this had no apparent consequences for fecundity. Instead, the number of flowers per inflorescence underpinned many of the reproductively important differences between color morphs. White morphs had more flowers per inflorescence, which itself was positively correlated with nectar production, seed predator occurrence, and total long-term seed production. The number of seeds per plant to survive predation, in contrast, was not directly associated with color or any other floral trait. Thus, although color differences may be associated with conflicting selection pressures, the selection appears to be associated with the number of flowers per inflorescence and its unmeasured correlates, rather than with inflorescence color itself.
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Affiliation(s)
- Jane E Carlson
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269, USA.
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35
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36
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Gowda V, Kress WJ. A Geographic Mosaic of Plant-Pollinator Interactions in the Eastern Caribbean Islands. Biotropica 2012. [DOI: 10.1111/j.1744-7429.2012.00915.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - W. John Kress
- Department of Botany; Smithsonian Institution; MRC-166; PO Box 37012; Washington; DC; 20013-0712; U.S.A
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37
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Nectar Secretion: Its Ecological Context and Physiological Regulation. SIGNALING AND COMMUNICATION IN PLANTS 2012. [DOI: 10.1007/978-3-642-23047-9_9] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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38
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Zywiec M, Delibes M, Fedriani JM. Microgeographical, inter-individual, and intra-individual variation in the flower characters of Iberian pear Pyrus bourgaeana (Rosaceae). Oecologia 2011; 169:713-22. [PMID: 22200854 PMCID: PMC3375002 DOI: 10.1007/s00442-011-2232-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2011] [Accepted: 12/07/2011] [Indexed: 12/01/2022]
Abstract
Flower characteristics have been traditionally considered relatively constant within species. However, there are an increasing number of examples of variation in flower characteristics. In this study, we examined the variation in attracting and rewarding flower characters at several ecological levels in a metapopulation of Pyrus bourgaeana in the Doñana area (SW Spain). We answered the following questions: what are the variances of morphological and nectar characters of flowers? How important are intra-individual and inter-individual variance in flower characters? Are there microgeographical differences in flower characters? And if so, are they consistent between years? In 2008 and 2009, we sampled flowers of 72 trees from five localities. For six flower morphological and two nectar characteristics, we calculated coefficients of variation (CV). The partitioning of total variation among-localities, among-individuals, and within-individuals was estimated. To analyze differences among localities and their consistency between years, we conducted generalized linear mixed models. The CVs of nectar characters were always higher than those of morphological characters. As expected, inter-individual variation was the main source of variation of flower morphology, but nectar characters had significant variation at both intra- and inter-individual levels. For most floral traits, there were no differences among localities. Our study documents that variation is a scale-dependent phenomenon and that it is essential to consider intra- and inter-individual variance when investigating the causes and consequences of variation. It also shows that single year studies of floral characters should be viewed with caution.
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Affiliation(s)
- Magdalena Zywiec
- Institute of Botany, Polish Academy of Sciences, ul. Lubicz 46, 31-512, Kraków, Poland.
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39
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Artz DR, Hsu CL, Nault BA. Influence of honey bee, Apis mellifera, hives and field size on foraging activity of native bee species in pumpkin fields. ENVIRONMENTAL ENTOMOLOGY 2011; 40:1144-1158. [PMID: 22251726 DOI: 10.1603/en10218] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The purpose of this study was to identify bee species active in pumpkin fields in New York and to estimate their potential as pollinators by examining their foraging activity. In addition, we examined whether foraging activity was affected by either the addition of hives of the honey bee, Apis mellifera L., or by field size. Thirty-five pumpkin (Cucurbita spp.) fields ranging from 0.6 to 26.3 ha, 12 supplemented with A. mellifera hives and 23 not supplemented, were sampled during peak flowering over three successive weeks in 2008 and 2009. Flowers from 300 plants per field were visually sampled for bees on each sampling date. A. mellifera, Bombus impatiens Cresson, and Peponapis pruinosa (Say) accounted for 99% of all bee visits to flowers. A. mellifera and B. impatiens visited significantly more pistillate flowers than would be expected by chance, whereas P. pruinosa showed no preference for visiting pistillate flowers. There were significantly more A. mellifera visits per flower in fields supplemented with A. mellifera hives than in fields not supplemented, but there were significantly fewer P. pruinosa visits in supplemented fields. The number of B. impatiens visits was not affected by supplementation, but was affected by number of flowers per field. A. mellifera and P. pruinosa visits were not affected by field size, but B. impatiens visited fewer flowers as field size increased in fields that were not supplemented with A. mellifera hives. Declining A. mellifera populations may increase the relative importance of B. impatiens in pollinating pumpkins in New York.
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Affiliation(s)
- Derek R Artz
- Department of Entomology, Cornell University, New York State Agricultural Experiment Station, Geneva, New York, USA.
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Zhang YW, Zhao JM, Yang CF, Gituru WR. Behavioural differences between male and female carpenter bees in nectar robbing and its effect on reproductive success in Glechoma longituba (Lamiaceae). PLANT BIOLOGY (STUTTGART, GERMANY) 2011; 13 Suppl 1:25-32. [PMID: 21134084 DOI: 10.1111/j.1438-8677.2009.00279.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Male and female nectar robbers may show significantly different behaviour on host plants and thus have different impacts on reproductive fitness of the plants. A 4-year study in natural populations of Glechoma longituba has shown that male carpenter bees (Xylocopa sinensis) are responsible for most of the nectar robbing from these flowers, while female bees account for little nectar robbing, demonstrating distinct behavioural differentiation between male and female bees in visiting flowers. The smaller male bee spends less time visiting a single flower than the larger female bee, consequently, the male bee is capable of visiting more flowers per unit time and has a higher foraging efficiency. Moreover, the robbing behaviour of female carpenter bees is more destructive and affects flower structures (ovules and nectaries) and floral life-span more than that of the male bee. According to the energy trade-off hypothesis, the net energy gain for male bees during nectar robbing greatly surpasses energy payout (17.72 versus 2.43 J), while the female bee net energy gain is barely adequate to meet energy payout per unit time (3.78 versus 2.39 J). The differences in net energy gain for male and female bees per unit time in nectar robbing are the likely cause of observed behavioural differences between the sexes. The differences in food resource preference between male and female bees constitute an optimal resource allocation pattern that enables the visitors to utilise floral resources more efficiently.
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Affiliation(s)
- Y-W Zhang
- Department of Biology, Eastern Liaoning University, Dandong, China
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41
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Yamawo A, Hada Y. Effects of light on direct and indirect defences against herbivores of young plants of Mallotus japonicus demonstrate a trade-off between two indirect defence traits. ANNALS OF BOTANY 2010; 106:143-8. [PMID: 20472698 PMCID: PMC2889801 DOI: 10.1093/aob/mcq093] [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: 12/22/2009] [Revised: 02/25/2010] [Accepted: 03/23/2010] [Indexed: 05/24/2023]
Abstract
BACKGROUND AND AIMS Although most studies on plant defence strategies have focused on a particular defence trait, some plant species develop multiple defence traits. To clarify the effects of light on the development of multiple defence traits, the production of direct and indirect defence traits of young plants of Mallotus japonicus were examined experimentally under different light conditions. METHODS The young plants were cultivated under three light conditions in the experimental field for 3 months from May to July. Numbers of ants and pearl bodies on leaves in July were examined. After cultivation, the plants were collected and the developments of trichomes and pellucid dots, and extrafloral nectaries (EFNs) on the leaves were examined. On plants without nectar-collecting insects, the size of EFNs and the volume of extrafloral nectar secreted from the EFNs were examined. KEY RESULTS Densities of trichomes and pellucid dots did not differ significantly among the plants under the different light conditions, suggesting that the chemical and physical defences function under both high and low light availability. The number of EFNs on the leaves did not differ significantly among the plants under the different light conditions, but there appeared to be a trade-off between the size of EFNs and the number of pearl bodies; the largest EFNs and the smallest number of pearl bodies were found under high light availability. EFN size was significantly correlated with the volume of extrafloral nectar secreted for 24 h. The number of ants on the plants was smaller under low light availability than under high and moderate light availability. CONCLUSIONS These results suggest that direct defence traits function regardless of light conditions, but light conditions affected the development of indirect defence traits.
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Affiliation(s)
- Akira Yamawo
- Department of Biosphere-Geosphere System Science, Okayama University of Science, Okayama 700-0005, Japan.
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42
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Affiliation(s)
- J H Ness
- Department of Biology, Skidmore College, Saratoga Springs, New York 12866, USA.
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Kaczorowski RL, Juenger TE, Holtsford TP. Heritability and correlation structure of nectar and floral morphology traits in Nicotiana alata. Evolution 2008; 62:1738-1750. [PMID: 18410534 DOI: 10.1111/j.1558-5646.2008.00400.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The heritability and genetic basis of nectar traits have been rarely studied in the field, where plants are exposed to environmental factors that could mask underlying genetic effects. Heritabilities and variance components were estimated for nectar and morphological traits of Nicotiana alata, using a partial diallel design. The main experiment was conducted in a Missouri experimental garden using a randomized block design with three plant density treatments, whereas a smaller experiment was conducted near native Brazil habitat to compare the environmental variance in traits between Missouri and Brazil. Significant heritability was detected for nectar volume and energy content, and for corolla tube length. Phenotypic correlations were significant between all traits investigated, whereas significant genetic correlations were only found between nectar volume and energy and between corolla limb width and mouth diameter. There were no significant family-by-density interactions detected in the Missouri field environment. All traits differed significantly between Missouri and Brazil environments, but significant genetic by environment (G x E) interactions between Missouri and Brazil were detected for only one trait. This study shows that nectar traits can be heritable despite considerable environmental variation.
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Affiliation(s)
- Rainee L Kaczorowski
- University of Missouri-Columbia, Division of Biological Sciences, 105 Tucker Hall, Columbia, Missouri 65211
- E-mail:
| | - Thomas E Juenger
- University of Texas at Austin, Section of Integrative Biology, 1 University Station, C0930 Austin, Texas 78712
| | - Timothy P Holtsford
- University of Missouri-Columbia, Division of Biological Sciences, 105 Tucker Hall, Columbia, Missouri 65211
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Canto A, Herrera CM, Medrano M, Pérez R, García IM. Pollinator foraging modifies nectar sugar composition in Helleborus foetidus (Ranunculaceae):An experimental test. AMERICAN JOURNAL OF BOTANY 2008; 95:315-20. [PMID: 21632356 DOI: 10.3732/ajb.95.3.315] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We experimentally tested the hypothesis that the extensive within-plant variation of nectar sugar composition in Helleborus foetidus (Ranunculaceae) and other species results from differences between flowers and nectaries in pollinator visitation history. Experiments were conducted to mimic single-nectary visits by wild-caught individuals of the main bee pollinators of H. foetidus, which were assayed for their capacity to modify the sugar composition of natural and artificial nectar. Experimental nectar probing with bee mouthparts induced extensive changes in proportional sugar composition 48 h after treatment, and bee taxa differed widely in their effects. Nectar probing by Andrena, medium-sized Anthophoridae, Apis mellifera, and Lasioglossum had no subsequent effects on nectar sugar composition, while probing by Bombus terrestris and B. pratorum induced an extensive reduction in percentage sucrose, a marked increase in percentage fructose, and a slight increase in percentage glucose. Results support the hypothesis that stochastic variations among flowers or nectaries in the taxonomic identity of recent visitors and their relative visitation frequencies may eventually generate very small-scale mosaics in nectar sugar composition. Changes in nectar sugar composition following bumblebee probing may be the consequence of nectar contamination with pollinator-borne nectarivorous yeasts.
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Affiliation(s)
- Azucena Canto
- Estación Biológica de Doñana, CSIC, Avenida de María Luisa s/n 41013 Sevilla, Spain
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Ornelas JF, Ordano M, De-Nova AJ, Quintero ME, Garland T. Phylogenetic analysis of interspecific variation in nectar of hummingbird-visited plants. J Evol Biol 2007; 20:1904-17. [PMID: 17714307 DOI: 10.1111/j.1420-9101.2007.01374.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
We tested whether phylogeny, flower size and/or altitude were significant predictors of interspecific variation in nectar production of hummingbird-visited plants in an assembled database (289 species, in 22 orders, 56 families and 131 genera). Although the study is focused on hummingbird-pollinated plants (241 plant species), plants with different pollinator syndromes (48 species) are also included in the analyses. Nectar volume secreted in a given time period (usually 24 h) by a given flower, its sugar concentration and corolla length were compiled mainly from the literature. Altitude was also obtained from the original references. Sugar production was computed basically as the product of nectar secretion and sugar concentration, and expressed on a per 24-h basis. All nectar traits and corolla length (all log transformed), as well as altitude, showed statistically significant phylogenetic signal. Both nonphylogenetic and phylogenetically informed (independent contrasts) analyses indicated a highly significant positive correlation between corolla length and both nectar volume and sugar production. In addition, altitude (which is partially a surrogate for temperature) was significantly negatively correlated with both sugar concentration and production. Possible reasons for coadaptation of nectar production and sugar production with corolla length are discussed.
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Affiliation(s)
- J F Ornelas
- Departamento de Biología Evolutiva, Instituto de Ecología, A.C., Xalapa, Veracruz, México.
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Lindroth RL, Donaldson JR, Stevens MT, Gusse AC. Browse Quality in Quaking Aspen (Populus tremuloides): Effects of Genotype, Nutrients, Defoliation, and Coppicing. J Chem Ecol 2007; 33:1049-64. [PMID: 17404817 DOI: 10.1007/s10886-007-9281-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2006] [Accepted: 03/12/2007] [Indexed: 10/23/2022]
Abstract
The consequences of interactions among genetic, ontogenetic, and environmental factors for the quality of winter-dormant tissues as food for browsing herbivores is poorly understood. We conducted two sequential common garden studies to assess the impacts of intraspecific genetic variation, nutrient availability, prior defoliation, and ontogenetic stage on the chemical quality of winter-dormant tissue in quaking aspen (Populus tremuloides Michx.). In the first study, saplings of 12 aspen genotypes were grown under low and high soil nutrient conditions, with or without two successive seasons of defoliation. Quantity and quality of current year's twig growth were assessed. Twig production varied among genotypes and declined under low nutrient availability, but showed little response to prior defoliation. Chemical quality of sapling twigs varied substantially among genotypes, and in response to nutrient availability and prior defoliation. Overall, browse quality improved (nitrogen levels increased while phenolic glycoside and condensed tannin levels decreased) after defoliation. Growth and chemical variables exhibited low to moderate clonal repeatability (broad sense heritability) values. Our second study employed the same 12 genotypes, grown under high-nutrient conditions and with or without two seasons of defoliation. The trees were coppiced to produce root sprouts, which were chemically assessed 1 yr later. Rejuvenation via coppicing led to increased levels of nitrogen, phenolic glycosides (salicortin), and tannins in root sprouts, and the magnitude of change varied among aspen genotypes. Signatures of defoliation nearly 2 yr earlier persisted in terms of elevated levels of phenolic glycosides in root sprouts of previously defoliated trees. Aspen forests likely present browsing herbivores with chemically heterogeneous environments because of the interactions of genetic, ontogenetic, and environmental factors that vary over space and time.
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Affiliation(s)
- Richard L Lindroth
- Department of Entomology, University of Wisconsin, Madison, WI 53706, USA.
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Doak P, Wagner D, Watson A. Variable extrafloral nectary expression and its consequences in quaking aspen. ACTA ACUST UNITED AC 2007. [DOI: 10.1139/b06-137] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Extrafloral nectaries (EFNs) are secretory glands most commonly linked to defensive mutualisms. Both a plant’s need for defense and the strength of defense provided by mutualists will vary with plant condition and local insect community. Thus, the benefit of EFNs may vary spatially and temporally. However, little attention has been paid to natural variation in the presence and abundance of EFNs within and among individuals of the same species. Quaking aspen, Populus tremuloides Michx., bear EFNs on a subset of their leaves. Here, we describe patterns of EFN expression on shoots within ramets, among ramets, and among putative clones in interior Alaska. We also examine the relationship between EFN presence and herbivory by both the very abundant aspen leaf miner, Phyllocnistis populiella Chambers, and less common chewing herbivores. The proportion of leaves bearing EFNs varied from 33% to 87% among distinct aspen stands. Within stands, short (1–2 m height) ramets had higher EFN frequency than their taller (>4 m) neighbors. Patterns of herbivory also differed between short and tall ramets. Compared with leaves without EFNs, those with EFNs suffered less mining damage on short ramets but slightly higher damage on tall ramets. Tall ramets suffered more chewing damage than short ramets, but this damage was unrelated to the presence of EFNs. Our results suggest that variable EFN expression may be explained by variation in the benefits of EFNs. Leaves with EFNs on short ramets benefit through reduction in leaf mining, but this benefit does not extend to tall ramets or other forms of herbivory.
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Affiliation(s)
- Patricia Doak
- Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775, USA
| | - Diane Wagner
- Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775, USA
| | - Adam Watson
- Institute of Arctic Biology, University of Alaska, Fairbanks, AK 99775, USA
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Galliot C, Hoballah ME, Kuhlemeier C, Stuurman J. Genetics of flower size and nectar volume in Petunia pollination syndromes. PLANTA 2006; 225:203-12. [PMID: 16871396 DOI: 10.1007/s00425-006-0342-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Accepted: 05/31/2006] [Indexed: 05/11/2023]
Abstract
The two related Petunia species, P. axillaris and P. integrifolia, are sympatric at various locations in South America but do not hybridise. Divergent pollinator preferences are believed to be in part responsible for their reproductive isolation. The volume of nectar produced and several components of flower morphology might contribute to pollinator-dependant reproductive isolation. In this study, we aimed to identify the genetic changes underlying the quantitative differences observed between these two Petunia species in flower size and nectar volume. We mapped quantitative trait loci (QTL) responsible for the different phenotypes of P. axillaris and P. integrifolia in an inter-specific backcross population. QTL of small to moderate effect control the differences in flower size and volume of nectar. In addition, we observed strong suppression of meiotic recombination in Petunia, even between closely related species, which precluded a fine resolution of QTL mapping. Thus, our data suggest that flower size and nectar volume are highly polygenic. They are likely to have evolved gradually through pollinator-mediated adaptation or reinforcement, and are not likely to have been primary factors in early steps of pollinator isolation of P. axillaris and P. integrifolia.
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Affiliation(s)
- Céline Galliot
- Institute of Plant Sciences, University of Berne, Altenbergrain 21, 3013 Berne, Switzerland.
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Fenster CB, Cheely G, Dudash MR, Reynolds RJ. Nectar reward and advertisement in hummingbird-pollinated Silene virginica (Caryophyllaceae). AMERICAN JOURNAL OF BOTANY 2006; 93:1800-1807. [PMID: 21642126 DOI: 10.3732/ajb.93.12.1800] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We tested for an association between nectar and various floral traits and investigated their roles as primary and secondary pollinator attractants in hummingbird-pollinated Silene virginica. Our goal was to gain insight into the mechanisms of pollinator-mediated selection that underlies floral trait divergence within the genus. In a field population of S. virginica, we measured five floral and eight vegetative traits and quantified nectar volume, nectar sugar concentration, and total sugar reward (nectar volume × nectar sugar concentration). All three components of nectar reward were positively correlated to flower size, and nectar volume varied significantly among individuals within the population. To ascertain whether the correlation of specific floral traits with nectar reward influences the behavior of the primary pollinator of S. virginica, the ruby-throated hummingbird, Archilochus colubris, we investigated whether A. colubris preferred the expression of floral traits associated with high nectar volume and total sugar reward. We accomplished this by constructing floral arrays consisting of artificial flowers that had equal nectar quantity and total sugar reward but that differed in petal area and corolla tube diameter, which were positively correlated with nectar quantity and total sugar reward in our field study. In observations of visitation frequencies to the various floral-trait combinations, hummingbirds preferentially visited artificial floral phenotypes with larger petal displays, with the greatest preference for floral phenotypes with both larger petals and wider corolla-tube diameters. This association between primary and secondary floral attractants and hummingbird discrimination of floral features supports the concept that the floral traits of S. virginica reflect pollinator-mediated selection by the principal pollinator.
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Affiliation(s)
- Charles B Fenster
- Department of Biology, University of Maryland, College Park, Maryland 20742 USA; Mountain Lake Biological Station, Pembroke, Virginia 24136 USA; and Department of Biology, Amherst College, Amherst, Massachusetts 01002 USA
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Ashman TL, Majetic CJ. Genetic constraints on floral evolution: a review and evaluation of patterns. Heredity (Edinb) 2006; 96:343-52. [PMID: 16598191 DOI: 10.1038/sj.hdy.6800815] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The characteristics of flowers influence most aspects of angiosperm reproduction, including the agents of pollination and patterns of mating. Thus, a clear view of the forces that mediate floral phenotypic evolution is central to understanding angiosperm diversity. Here, we inform on the capacity for floral phenotype to respond to selection by reviewing published data on heritabilities and genetic correlations for several classes of floral traits (primary sexual, attraction, mating system) in hermaphroditic plants. We find significant heritability for all floral traits but also variation among them, as well as a tendency for heritability to vary with mating system, but not life history. We additionally test predictions stemming from life history theory (eg, negative covariation between male-female traits and flower size-flower number), and ideas concerning the extent and pattern of genetic integration between flowers and leaves, and between the sexes of dioecious and gynodioecious species. We find mixed evidence for life history tradeoffs. We find strong support for floral integration and its relation with floral morphology (actinomorphy vs zygomorphy) and for a decoupling of floral and vegetative traits, but no evidence that modular integration varies with floral morphology. Lastly, we find mixed evidence for a relationship between the level of sexual dimorphism in attraction traits and the between-sex correlation in gender dimorphic plants.
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Affiliation(s)
- T-L Ashman
- 1Department of Biological Sciences, University of Pittsburgh, 4249 Fifth Ave and Ruskin, Pittsburgh, PA 15260, USA.
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