1
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Barman M, Tenhaken R, Dötterl S. Negative and sex-specific effects of drought on flower production, resources and pollinator visitation, but not on floral scent in monoecious Cucurbita pepo. THE NEW PHYTOLOGIST 2024. [PMID: 39117354 DOI: 10.1111/nph.20016] [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: 02/02/2024] [Accepted: 04/10/2024] [Indexed: 08/10/2024]
Abstract
The globally changing climatic condition is increasing the incidences of drought in several parts of the world. This is predicted and already shown to not only impact plant growth and flower development, but also plant-pollinator interactions and the pollination success of entomophilous plants. However, there is a large gap in our understanding of how drought affects the different flowers and pollen transfer among flowers in sexually polymorphic species. Here, we evaluated in monoecious Styrian oil pumpkin, and separately for female and male flowers, the responses of drought stress on flower production, petal size, nectar, floral scent and visitation by bumblebee pollinators. Drought stress adversely affected all floral traits studied, except floral scent. Although both flower sexes were adversely affected by drought stress, the effects were more severe on female flowers, with most of the female flowers even aborted before opening. The drought had negative effects on floral visitation by the pollinators, which generally preferred female flowers. Overall, our study highlights that the two flower sexes of a monoecious plant species are differently affected by drought stress and calls for further investigations to better understand the cues used by the pollinators to discriminate against male flowers and against flowers of drought-stressed plants.
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Affiliation(s)
- Monica Barman
- Department of Environment and Biodiversity, Paris Lodron University of Salzburg, Hellbrunnerstrasse 34, Salzburg, 5020, Austria
- Leibniz Institute of Vegetable and Ornamental Crops (IGZ), Theodor-Echtermeyer-Weg 1, Großbeeren, 14979, Germany
| | - Raimund Tenhaken
- Department of Environment and Biodiversity, Paris Lodron University of Salzburg, Hellbrunnerstrasse 34, Salzburg, 5020, Austria
| | - Stefan Dötterl
- Department of Environment and Biodiversity, Paris Lodron University of Salzburg, Hellbrunnerstrasse 34, Salzburg, 5020, Austria
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2
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Duell EB, Baum KA, Wilson GWT. Drought reduces productivity and anti-herbivore defences, but not mycorrhizal associations, of perennial prairie forbs. PLANT BIOLOGY (STUTTGART, GERMANY) 2024; 26:204-213. [PMID: 38168486 DOI: 10.1111/plb.13604] [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: 06/22/2023] [Accepted: 11/27/2023] [Indexed: 01/05/2024]
Abstract
During drought, plants allocate resources to aboveground biomass production and belowground carbohydrate reserves, often at the expense of production of defence traits. Additionally, drought has been shown to alter floral resources, with potential implications for plant-pollinator interactions. Although soil symbionts, such as arbuscular mycorrhizal (AM) fungi, can alleviate drought stress in plants, certain levels of drought may negatively impact this relationship, with potential cascading effects. Because of their importance to plant and animal community diversity, we examined effects of drought on biomass production, physical defence properties, nectar production, and associated AM fungal abundance of five common prairie forb species in a greenhouse study. Reduced soil moisture decreased vegetative biomass production. Production of trichomes and latex decreased under drought, relative to well-watered conditions. Ruellia humilis flowers produced less nectar under drought, relative to well-watered conditions. Intra-radical AM fungal colonization was not significantly affected by drought, although extra-radical AM fungal biomass associated with S. azurea decreased following drought. Overall, grassland forb productivity, defence, and nectar production were negatively impacted by moderate drought, with possible negative implications for biotic interactions. Reduced flower and nectar production may lead to fewer pollinator visitors, which may contribute to seed limitation in forb species. Reduced physical defences increase the likelihood of herbivory, further decreasing the ability to store energy for essential functions, such as reproduction. Together, these results suggest drought can potentially impact biotic interactions between plants and herbivores, pollinators, and soil symbionts, and highlights the need for direct assessments of these relationships under climate change scenarios.
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Affiliation(s)
- E B Duell
- Kansas Biological Survey & Center for Ecological Research, Lawrence, KS, USA
| | - K A Baum
- Department of Integrative Biology, Oklahoma State University, Stillwater, OK, USA
| | - G W T Wilson
- Department of Natural Resource Ecology & Management, Oklahoma State University, Stillwater, OK, USA
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3
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Hamon LE, Youngsteadt E, Irwin RE, Sorenson CE. As prey and pollinators, insects increase reproduction and allow for outcrossing in the carnivorous plant Dionaea muscipula. AMERICAN JOURNAL OF BOTANY 2024; 111:e16279. [PMID: 38290989 DOI: 10.1002/ajb2.16279] [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: 10/28/2023] [Revised: 12/08/2023] [Accepted: 12/11/2023] [Indexed: 02/01/2024]
Abstract
PREMISE Understanding the factors that limit reproductive success is a key component of plant biology. Carnivorous plants rely on insects as both nutrient sources and pollinators, providing a unique system for studying the effects of both resource and pollen limitation on plant reproduction. METHODS We conducted a field experiment using wild-growing Dionaea muscipula J. Ellis (Droseraceae) in which we manipulated prey and pollen in a factorial design and measured flower production, number of fruits, and number of seeds. Because understanding reproduction requires knowledge of a plant species' reproductive and pollination biology, we also examined the pollination system, per-visit pollinator effectiveness, and pollen-ovule (P/O) ratio of D. muscipula. RESULTS Plants that received supplemental prey produced more flowers than control plants. They also had a higher overall fitness estimate (number of flowers × fruit set (total fruits/total flowers) × seeds per fruit), although this benefit was significant only when prey supplementation occurred in the previous growing season. Neither pollen supplementation nor the interaction between pollen and prey supplementation significantly affected overall plant fitness. CONCLUSIONS This study reinforces the reliance of D. muscipula on adequate prey capture for flower, fruit, and seed production and a mobile pollen vector for reproduction, indicating the importance of considering insects as part of an effective conservation management plan for this species.
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Affiliation(s)
- Laura E Hamon
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, North Carolina, 27695, USA
- Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, 27695, USA
| | - Elsa Youngsteadt
- Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, 27695, USA
- Center for Geospatial Analytics, North Carolina State University, Raleigh, North Carolina, USA
| | - Rebecca E Irwin
- Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, 27695, USA
| | - Clyde E Sorenson
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, North Carolina, 27695, USA
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4
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Pyke GH, Ren ZX. Floral nectar production: what cost to a plant? Biol Rev Camb Philos Soc 2023; 98:2078-2090. [PMID: 37461187 DOI: 10.1111/brv.12997] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 05/29/2023] [Accepted: 06/30/2023] [Indexed: 11/07/2023]
Abstract
Floral nectar production is central to plant pollination, and hence to human wellbeing. As floral nectar is essentially a solution in water of various sugars, it is likely a valuable plant resource, especially in terms of energy, with plants experiencing costs/trade-offs associated with its production or absorption and adopting mechanisms to regulate nectar in flowers. Possible costs of nectar production may also influence the evolution of nectar volume, concentration and composition, of pollination syndromes involving floral nectar, and the production of some crops. There has been frequent agreement that costs of floral nectar production are significant, but relevant evidence is scant and difficult to interpret. Convincing direct evidence comes from experimental studies that relate either enhanced nectar sugar production (through repeated nectar removal) to reduced ability to produce seeds, or increased sugar availability (through absorption of additional artificial nectar) to increased seed production. Proportions of available photosynthate allocated by plants to nectar production may also indicate nectar cost. However, such studies are rare, some do not include treatments of all (or almost all) flowers per plant, and all lack quantitative cost-benefit comparisons for nectar production. Additional circumstantial evidence of nectar cost is difficult to interpret and largely equivocal. Future research should repeat direct experimental approaches that relate reduced or enhanced nectar sugar availability for a plant with consequent ability to produce seeds. To avoid confounding effects of inter-flower resource transfer, each plant should experience a single treatment, with treatment of all or almost all flowers per plant. Resource allocation by plants, pathways used for resource transfer, and the locations of resource sources and sinks should also be investigated. Future research should also consider extension of nectar cost into other areas of biology. For example, evolutionary models of nectar production are rare but should be possible if plant fitness gains and costs associated with nectar production are expressed in the same currency, such as energy. It should then be possible to understand observed nectar production for different plant species and pollination syndromes involving floral nectar. In addition, potential economic benefits should be possible to assess if relationships between nectar production and crop value are evaluated.
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Affiliation(s)
- Graham H Pyke
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China
- School of Natural Sciences, Macquarie University, Balaclava Rd, North Ryde, 2113, New South Wales, Australia
| | - Zong-Xin Ren
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China
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5
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García Y, Dow BS, Parachnowitsch AL. Water deficit changes patterns of selection on floral signals and nectar rewards in the common morning glory. AOB PLANTS 2023; 15:plad061. [PMID: 37899982 PMCID: PMC10601024 DOI: 10.1093/aobpla/plad061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 08/24/2023] [Indexed: 10/31/2023]
Abstract
Understanding whether and how resource limitation alters phenotypic selection on floral traits is key to predict the evolution of plant-pollinator interactions under climate change. Two important resources predicted to decline with our changing climate are pollinators and water in the form of increased droughts. Most work, however, has studied these selective agents separately and in the case of water deficit, studies are rare. Here, we use the common morning glory (Ipomoea purpurea) to investigate the effects of experimental reduction in pollinator access and water availability on floral signals and nectar rewards and their effects on phenotypic selection on these traits. We conducted a manipulative experiment in a common garden, where we grew plants in three treatments: (1) pollinator restriction, (2) water reduction and (3) unmanipulated control. Plants in pollinator restriction and control treatments were well-watered compared to water deficit. We found that in contrast to pollinator restriction, water deficit had strong effects altering floral signals and nectar rewards but also differed in the direction and strength of selection on these traits compared to control plants. Water deficit increased the opportunity for selection, and selection in this treatment favoured lower nectar volumes and larger floral sizes, which might further alter pollinator visitation. In addition, well-watered plants, both in control and pollinator deficit, showed similar patterns of selection to increase nectar volume suggesting non-pollinator-mediated selection on nectar. Our study shows that floral traits may evolve in response to reduction in water access faster than to declines in pollinators and reinforces that abiotic factors can be important agents of selection for floral traits. Although only few experimental selection studies have manipulated access to biotic and abiotic resources, our results suggest that this approach is key for understanding how pollination systems may evolve under climate change.
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Affiliation(s)
- Yedra García
- Department of Biology, University of New Brunswick, 10 Bailey Dr, Fredericton, NB E3B 5A3, Canada
| | - Benjamin S Dow
- Department of Biology, University of New Brunswick, 10 Bailey Dr, Fredericton, NB E3B 5A3, Canada
| | - Amy L Parachnowitsch
- Department of Biology, University of New Brunswick, 10 Bailey Dr, Fredericton, NB E3B 5A3, Canada
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6
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Lawrence SL, Hazlehurst J. Hummingbird foraging preferences during extreme heat events. Ecol Evol 2023; 13:e10053. [PMID: 37181210 PMCID: PMC10171992 DOI: 10.1002/ece3.10053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 04/04/2023] [Accepted: 04/17/2023] [Indexed: 05/16/2023] Open
Abstract
Climate change is projected to increase global mean annual temperatures as well as the frequency and intensity of extreme heat events. These changes are anticipated to alter the behavior of animals as they seek to thermoregulate in extreme heat. An important area of research is understanding how mutualistic interactions between animals and plants, such as pollination, will be affected by the cascading effects of extreme heat on animal foraging behavior. In this study, we used an experimental and observational approach to quantify the effects of extreme heat on hummingbird foraging preferences for nectar sources in shady versus sunny microsites. We also quantified pollen deposition using artificial stigmas at these sites to quantify potential cascading effects on plant reproduction. We hypothesized that hummingbirds would respond to extreme heat by preferentially foraging in shady microsites, and that this would reduce pollen deposition in sunny microsites on hot days. We found little support for this hypothesis, instead hummingbirds preferred to forage in sunny microsites regardless of ambient temperature. We also found weak evidence for higher pollen deposition in sunny microsites on hot days.
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Affiliation(s)
- Sabina Lucke Lawrence
- Department of Biological SciencesCalifornia State University East BayHaywardCaliforniaUSA
| | - Jenny Hazlehurst
- Department of Biological SciencesCalifornia State University East BayHaywardCaliforniaUSA
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7
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Wu Y, Liu G, Sletvold N, Duan X, Tong Z, Li Q. Soil water and nutrient availability interactively modify pollinator-mediated directional and correlational selection on floral display. THE NEW PHYTOLOGIST 2023; 237:672-683. [PMID: 36229922 DOI: 10.1111/nph.18537] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 09/30/2022] [Indexed: 06/16/2023]
Abstract
The individual and combined effects of abiotic factors on pollinator-mediated selection on floral traits are not well documented. To examine potential interactive effects of water and nutrient availability on pollinator-mediated selection on three floral display traits of Primula tibetica, we manipulated pollination and nutrient availability in a factorial experiment, conducted at two common garden sites with different soil water content (natural vs addition). We found that both water and nutrient availability affected floral trait expression in P. tibetica and that hand pollination increased seed production most when both nutrient content and water content were high, indicating joint pollen and resource limitation. We documented selection on all floral traits, and pollinators contributed to directional and correlational selection on plant height and number of flowers. Soil water and nutrient availability interactively influenced the strength of both pollinator-mediated directional and correlational selection, with significant selection observed when nutrient or water availability was high, but not when none or both were added. The results suggest that resource limitation constrains the response of P. tibetica to among-individual variation in pollen receipt, that addition of nutrients or water leads to pollinator-mediated selection and that effects of the two abiotic factors are nonadditive.
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Affiliation(s)
- Yun Wu
- School of Architecture and Civil Engineering, Xihua University, Chengdu, 610039, China
| | - Guangli Liu
- College of Landscape Architecture, Sichuan Agricultural University, Chengdu, 611130, China
| | - Nina Sletvold
- Plant Ecology and Evolution, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden
| | - Xuyu Duan
- College of Landscape Architecture, Sichuan Agricultural University, Chengdu, 611130, China
| | - Zhaoli Tong
- Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology, Yunnan University, Kunming, 650091, China
- Laboratory of Ecology and Evolutionary Biology, School of Ecology and Environmental Science, Yunnan University, Kunming, 650091, China
| | - Qingjun Li
- Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology, Yunnan University, Kunming, 650091, China
- Laboratory of Ecology and Evolutionary Biology, School of Ecology and Environmental Science, Yunnan University, Kunming, 650091, China
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8
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De Diego FC, Robbiati FO, Gaitán JJ, Fortunato RH. Morphological and distributional patterns of native and invasive Trifolium (Papilionoideae, Leguminosae) species in southern South America. SYST BIODIVERS 2022. [DOI: 10.1080/14772000.2022.2126022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Fernando Carlos De Diego
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Rivadavia 1917, (C1033AAJ) CABA, Argentina
- Instituto de Recursos Biológicos, CIRN, INTA, Nicolás Repetto y de Los Reseros s/n°, Hurlingham, 1686, Buenos Aires, Argentina
- Escuela Superior de Ingeniería, Informática y Ciencias Agroalimentarias, Universidad de Morón, Cabildo 134, Morón 1708, Buenos Aires, Argentina
| | - Federico Omar Robbiati
- Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Av. Vélez Sarsfield 299, Córdoba, X5000JJC, Prov. Córdoba, Argentina
| | - Juan José Gaitán
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Rivadavia 1917, (C1033AAJ) CABA, Argentina
- Instituto de Suelos, CIRN, INTA, Nicolás Repetto y de Los Reseros s/n°, Hurlingham, 1686, Buenos Aires, Argentina
- Departamento de Tecnología, Universidad Nacional de Luján, Luján, 6700, Buenos Aires, Argentina
| | - Renée Hersilia Fortunato
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Rivadavia 1917, (C1033AAJ) CABA, Argentina
- Escuela Superior de Ingeniería, Informática y Ciencias Agroalimentarias, Universidad de Morón, Cabildo 134, Morón 1708, Buenos Aires, Argentina
- Instituto de Botánica Darwinion (CONICET/ANCEFN), Labardén 200, Acassuso, 1641, Buenos Aires, Argentina
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9
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Gomes SE, Baguskas SA. Coastal Fog Enhances Physiological Function of Seaside Daisies (Erigeron glaucus). WEST N AM NATURALIST 2022. [DOI: 10.3398/064.082.0309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Affiliation(s)
- Sarah E. Gomes
- Department of Geography and Environment, San Francisco State University, San Francisco, CA 94132
| | - Sara A. Baguskas
- Department of Geography and Environment, San Francisco State University, San Francisco, CA 94132
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10
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Cuartas‐Domínguez M, Robles V, Arroyo MTK. Large flowers can be short‐lived: Insights from a high Andean cactus. Ecol Evol 2022. [DOI: 10.1002/ece3.9231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
| | - Valeria Robles
- Centro Internacional Cabo de Hornos (CHIC) Universidad de Magallanes Puerto Williams Chile
| | - Mary T. K. Arroyo
- Facultad de Ciencias Universidad de Chile Santiago Chile
- Centro Internacional Cabo de Hornos (CHIC) Universidad de Magallanes Puerto Williams Chile
- Instituto de Ecología y Biodiversidad (IEB) Barrio Universitario Concepción Chile
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11
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Cabon V, Kracht A, Seitz B, Kowarik I, von der Lippe M, Buchholz S. Urbanisation modulates the attractiveness of plant communities to pollinators by filtering for floral traits. OIKOS 2022. [DOI: 10.1111/oik.09071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Valentin Cabon
- Technische Univ. Berlin, Dept of Ecology Berlin Germany
- Univ. de Rennes 1, CNRS‐ECOBIO (Ecosystèmes, Biodiversité, Évolution) UMR 6553 Rennes France
| | - Alice Kracht
- Technische Univ. Berlin, Dept of Ecology Berlin Germany
| | - Birgit Seitz
- Technische Univ. Berlin, Dept of Ecology Berlin Germany
- Berlin‐Brandenburg Inst. of Advanced Biodiversity Research (BBIB) Berlin Germany
| | - Ingo Kowarik
- Technische Univ. Berlin, Dept of Ecology Berlin Germany
- Berlin‐Brandenburg Inst. of Advanced Biodiversity Research (BBIB) Berlin Germany
| | - Moritz von der Lippe
- Technische Univ. Berlin, Dept of Ecology Berlin Germany
- Berlin‐Brandenburg Inst. of Advanced Biodiversity Research (BBIB) Berlin Germany
| | - Sascha Buchholz
- Berlin‐Brandenburg Inst. of Advanced Biodiversity Research (BBIB) Berlin Germany
- Inst. of Landscape Ecology, Univ. of Münster Münster Germany
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12
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Akter A, Klečka J. Water stress and nitrogen supply affect floral traits and pollination of the white mustard, Sinapis alba (Brassicaceae). PeerJ 2022; 10:e13009. [PMID: 35462774 PMCID: PMC9022644 DOI: 10.7717/peerj.13009] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 02/04/2022] [Indexed: 01/11/2023] Open
Abstract
Changes in environmental conditions are likely to have a complex effect on the growth of plants, their phenology, plant-pollinator interactions, and reproductive success. The current world is facing an ongoing climate change along with other human-induced environmental changes. Most research has focused on the impact of increasing temperature as a major driving force for climate change, but other factors may have important impacts on plant traits and pollination too and these effects may vary from season to season. In addition, it is likely that the effects of multiple environmental factors, such as increasing temperature, water availability, and nitrogen enrichment are not independent. Therefore, we tested the impact of two key factors-water, and nitrogen supply-on plant traits, pollination, and seed production in Sinapis alba (Brassicaceae) in three seasons defined as three temperature conditions with two levels of water and nitrogen supply in a factorial design. We collected data on multiple vegetative and floral traits and assessed the response of pollinators in the field. Additionally, we evaluated the effect of growing conditions on seed set in plants exposed to pollinators and in hand-pollinated plants. Our results show that water stress impaired vegetative growth, decreased flower production, and reduced visitation by pollinators and seed set, while high amount of nitrogen increased nectar production under low water availability in plants grown in the spring. Temperature modulated the effect of water and nitrogen availability on vegetative and floral traits and strongly affected flowering phenology and flower production. We demonstrated that changes in water and nitrogen availability alter plant vegetative and floral traits, which impacts flower visitation and consequently plant reproduction. We conclude that ongoing environmental changes such as increasing temperature, altered precipitation regimes and nitrogen enrichment may thus affect plant-pollinator interactions with negative consequences for the reproduction of wild plants and insect-pollinated crops.
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Affiliation(s)
- Asma Akter
- Department of Zoology, Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic,Institute of Entomology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Jan Klečka
- Institute of Entomology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czech Republic
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13
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Wu Y, Duan X, Tong Z, Li Q. Pollinator-Mediated Selection on Floral Traits of Primula tibetica Differs Between Sites With Different Soil Water Contents and Among Different Levels of Nutrient Availability. FRONTIERS IN PLANT SCIENCE 2022; 13:807689. [PMID: 35300008 PMCID: PMC8921772 DOI: 10.3389/fpls.2022.807689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 02/09/2022] [Indexed: 06/14/2023]
Abstract
Abiotic environmental factors are predicted to affect plant traits and the intensity of plant-pollinator interactions. However, knowledge of their potential effects on pollinator-mediated selection on floral traits is still limited. We separately estimated the effects of soil water (two sites with different soil water contents) and N-P-K nutrient availability (different levels of nutrient addition) on pollinator-mediated selection on floral traits of Primula tibetica (an insect-pollinated perennial herbaceous species). Our results demonstrated that floral traits, plant reproductive success and pollinator-mediated selection on floral traits varied between sites with different soil water contents and among different levels of nutrient addition. The strength of pollinator-mediated selection was stronger at the site with low soil water content than at the site with high soil water content, and first decreased and then increased with increasing N-P-K nutrient addition. Our results support the hypothesis that abiotic environmental factors influence the importance of pollinators in shaping floral evolution.
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Affiliation(s)
- Yun Wu
- School of Architecture and Civil Engineering, Xihua University, Chengdu, China
- Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology, Yunnan University, Kunming, China
- Laboratory of Ecology and Evolutionary Biology, School of Ecology and Environmental Science, Yunnan University, Kunming, China
| | - Xuyu Duan
- College of Landscape Architecture, Sichuan Agricultural University, Chengdu, China
| | - Zhaoli Tong
- Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology, Yunnan University, Kunming, China
- Laboratory of Ecology and Evolutionary Biology, School of Ecology and Environmental Science, Yunnan University, Kunming, China
| | - Qingjun Li
- Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology, Yunnan University, Kunming, China
- Laboratory of Ecology and Evolutionary Biology, School of Ecology and Environmental Science, Yunnan University, Kunming, China
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14
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Powers JM, Briggs HM, Dickson RG, Li X, Campbell DR. Earlier snow melt and reduced summer precipitation alter floral traits important to pollination. GLOBAL CHANGE BIOLOGY 2022; 28:323-339. [PMID: 34582609 DOI: 10.1111/gcb.15908] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 09/14/2021] [Indexed: 06/13/2023]
Abstract
Climate change can cause changes in expression of organismal traits that influence fitness. In flowering plants, floral traits can respond to drought, and that phenotypic plasticity has the potential to affect pollination and plant reproductive success. Global climate change is leading to earlier snow melt in snow-dominated ecosystems as well as affecting precipitation during the growing season, but the effects of snow melt timing on floral morphology and rewards remain unknown. We conducted crossed manipulations of spring snow melt timing (early vs. control) and summer monsoon precipitation (addition, control, and reduction) that mimicked recent natural variation, and examined plastic responses in floral traits of Ipomopsis aggregata over 3 years in the Rocky Mountains. We tested whether increased summer precipitation compensated for earlier snow melt, and if plasticity was associated with changes in soil moisture and/or leaf gas exchange. Lower summer precipitation decreased corolla length, style length, corolla width, sepal width, and nectar production, and increased nectar concentration. Earlier snow melt (taking into account natural and experimental variation) had the same effects on those traits and decreased inflorescence height. The effect of reduced summer precipitation was stronger in earlier snow melt years for corolla length and sepal width. Trait reductions were explained by drier soil during the flowering period, but this effect was only partially explained by how drier soils affected plant water stress, as measured by leaf gas exchange. We predicted the effects of plastic trait changes on pollinator visitation rates, pollination success, and seed production using prior studies on I. aggregata. The largest predicted effect of drier soil on relative fitness components via plasticity was a decrease in male fitness caused by reduced pollinator rewards (nectar production). Early snow melt and reduced precipitation are strong drivers of phenotypic plasticity, and both should be considered when predicting effects of climate change on plant traits in snow-dominated ecosystems.
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Affiliation(s)
- John M Powers
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California, USA
- Rocky Mountain Biological Laboratory, Crested Butte, Colorado, USA
| | - Heather M Briggs
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California, USA
- Rocky Mountain Biological Laboratory, Crested Butte, Colorado, USA
| | - Rachel G Dickson
- Rocky Mountain Biological Laboratory, Crested Butte, Colorado, USA
| | - Xinyu Li
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California, USA
- Rocky Mountain Biological Laboratory, Crested Butte, Colorado, USA
| | - Diane R Campbell
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California, USA
- Rocky Mountain Biological Laboratory, Crested Butte, Colorado, USA
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15
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Recart W, Campbell DR. Water availability affects the relationship between pollen intensity and seed production. AOB PLANTS 2021; 13:plab074. [PMID: 34987746 PMCID: PMC8711293 DOI: 10.1093/aobpla/plab074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 11/30/2021] [Indexed: 06/14/2023]
Abstract
Seed production can be affected by water availability and also depend on the amount (pollen intensity) and quality of pollen deposited. The way pollen receipt on the stigma translates into seeds produced follows that of a saturating dose-response. Not only can water availability and pollen intensity each influence seed production, these factors could interact in their effects on seed production. Changes to the relationship between seed production and pollen intensity can in turn influence pollinator effectiveness and pollinator-mediated selection. We asked how water availability affected indices of plant fitness (seed set, fruit set and seed mass) and the relationship between pollen intensity and seed production in Phacelia parryi. We conducted a greenhouse experiment where we manipulated water availability (either high- or low-water) to pollen recipient plants and hand-pollinated each plant with a range of pollen intensities. We conducted 703 hand-pollinations on 30 plants. For each hand-pollinated flower we measured pollen deposited, seed production and seed mass. We then generated a piecewise regression of the relationship between pollen intensity and seed production, and determined average effects of water on plant fitness measures. This experiment was paired with a field observational study aimed to document natural variation in pollen deposition. Average seed production per fruit was 21 % higher in the high-watered plants. The relationship between pollen intensity and seed production differed between the two water treatments. Plants under high-water exhibited a wider range in which pollen deposition increased seed production. Average natural pollen intensities fell within different regions of the piecewise regression for low- and high-water plants. Water availability can alter the efficiency by which pollen received is translated into seeds produced. Our greenhouse data suggest that only under certain pollen intensity environments will water availability affect how pollen received is translated into seeds produced.
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Affiliation(s)
- Wilnelia Recart
- Department of Biology, University of San Diego, 5998 Alcalá Park, San Diego, CA 92110, USA
| | - Diane R Campbell
- Department of Ecology and Evolutionary Biology, University of California, Irvine, 321 Steinhaus Hall, Irvine, CA 92697-2525, USA
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16
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Kuppler J, Kotowska MM. A meta-analysis of responses in floral traits and flower-visitor interactions to water deficit. GLOBAL CHANGE BIOLOGY 2021; 27:3095-3108. [PMID: 33774883 DOI: 10.1111/gcb.15621] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Accepted: 03/10/2021] [Indexed: 06/12/2023]
Abstract
Alterations in water availability and drought events as predicted by climate change scenarios will increasingly impact natural communities with effects already emerging at present. Water deficit leads to increasing physiological stress in plants, likely affecting floral development and causing changes in floral morphology, nectar and pollen production or scent. Understanding how these floral traits are altered by water deficit is necessary to predict changes in plant-pollinator interactions and how communities are impacted in the future. Here we employ a meta-analysis approach to synthesize the current evidence of experimental water deficit on floral traits and plant-pollinator interactions. Furthermore, we explore experimental factors potentially increasing heterogeneity between studies and provide ideas how to enhance comparability between studies. In the end, we highlight future directions and knowledge gaps for floral traits and plant-pollinator interactions under water deficit. Our analysis showed consistent decreases in floral size, number of flowers and nectar volume to reduced water availability. Other floral traits such as the start of flowering or herkogamy showed no consistent pattern. This indicates that effects of reduced water availability differ between specific traits that are potentially involved in different functions such as pollinator attraction or efficiency. We found no general decreasing visitation rates with water deficit for flower-visitor interactions. Furthermore, the comparison of available studies suggests that increased reporting of plant stress severity and including more hydraulic and physiological measurements will improve the comparability across experiments and aid a more mechanistic understanding of plant-pollinator interactions under altered environmental conditions. Overall, our results show that water deficit has the potential to strongly affect plant-pollinator interactions via changes in specific floral traits. Linking these changes to pollination services and pollinator performance is one crucial step for understanding how changing water availability and drought events under climate change will alter plant and pollinator communities.
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Affiliation(s)
- Jonas Kuppler
- Institute of Evolutionary Ecology and Conservation Genomics, Ulm University, Ulm, Germany
| | - Martyna M Kotowska
- Plant Ecology and Ecosystems Research, University of Göttingen, Göttingen, Germany
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17
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Gallagher MK, Campbell DR. Experimental Test of the Combined Effects of Water Availability and Flowering Time on Pollinator Visitation and Seed Set. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.641693] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Climate change is likely to alter both flowering phenology and water availability for plants. Either of these changes alone can affect pollinator visitation and plant reproductive success. The relative impacts of phenology and water, and whether they interact in their impacts on plant reproductive success remain, however, largely unexplored. We manipulated flowering phenology and soil moisture in a factorial experiment with the subalpine perennial Mertensia ciliata (Boraginaceae). We examined responses of floral traits, floral abundance, pollinator visitation, and composition of visits by bumblebees vs. other pollinators. To determine the net effects on plant reproductive success, we also measured seed production and seed mass. Reduced water led to shorter, narrower flowers that produced less nectar. Late flowering plants produced fewer and shorter flowers. Both flowering phenology and water availability influenced pollination and reproductive success. Differences in flowering phenology had greater effects on pollinator visitation than did changes in water availability, but the reverse was true for seed production and mass, which were enhanced by greater water availability. The probability of receiving a flower visit declined over the season, coinciding with a decline in floral abundance in the arrays. Among plants receiving visits, both the visitation rate and percent of non-bumblebee visitors declined after the first week and remained low until the final week. We detected interactions of phenology and water on pollinator visitor composition, in which plants subject to drought were the only group to experience a late-season resurgence in visits by solitary bees and flies. Despite that interaction, net reproductive success measured as seed production responded additively to the two manipulations of water and phenology. Commonly observed declines in flower size and reward due to drought or shifts in phenology may not necessarily result in reduced plant reproductive success, which in M. ciliata responded more directly to water availability. The results highlight the need to go beyond studying single responses to climate changes, such as either phenology of a single species or how it experiences an abiotic factor, in order to understand how climate change may affect plant reproductive success.
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18
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Kuppler J, Wieland J, Junker RR, Ayasse M. Drought-induced reduction in flower size and abundance correlates with reduced flower visits by bumble bees. AOB PLANTS 2021; 13:plab001. [PMID: 33628409 PMCID: PMC7891244 DOI: 10.1093/aobpla/plab001] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/05/2021] [Indexed: 05/04/2023]
Abstract
Reduced water availability can cause physiological stress in plants that affects floral development leading to changes in floral morphology and traits that mediate interactions with pollinators. As pollinators can detect small changes in trait expressions, drought-induced changes in floral traits could affect pollinator visitations. However, the linkage between changes in floral traits and pollinator visitations under drought conditions is not well explored. We, therefore, tested whether drought-induced changes in floral morphology and abundance of flowers are linked to changes in pollinator visitations. We conducted flight cage experiments with a radio frequency identification system for automated visitation recordings with bumble bees (Bombus terrestris) and common charlock (Sinapis arvensis) as the model system. In total, we recorded interactions for 31 foraging bumble bees and 6569 flower visitations. We found that decreasing soil moisture content correlated with decreasing size of all measured morphological traits except stamen length and nectar tube width. The reductions in floral size, petal width and length, nectar tube depth and number of flowers resulted in decreasing visitation rates by bumble bees. These decreasing visitations under lower soil moisture availability might be explained by lower numbers of flowers and thus a reduced attractiveness and/or by increased difficulties experienced by bumble bees in handling smaller flowers. Whether these effects act additively or synergistically on pollinator behaviour and whether this leads to changes in pollen transfer and to different selectionp ressures require further investigation.
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Affiliation(s)
- J Kuppler
- Institute of Evolutionary Ecology and Conservation Genomics, Ulm University, Ulm, Germany
- Corresponding author’s e-mail address:
| | - J Wieland
- Institute of Evolutionary Ecology and Conservation Genomics, Ulm University, Ulm, Germany
| | - R R Junker
- Evolutionary Ecology of Plants, Department of Biology, Philipps-University Marburg, Marburg, Germany
- Department of Biosciences, University of Salzburg, Salzburg, Austria
| | - M Ayasse
- Institute of Evolutionary Ecology and Conservation Genomics, Ulm University, Ulm, Germany
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19
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Höfer RJ, Ayasse M, Kuppler J. Bumblebee Behavior on Flowers, but Not Initial Attraction, Is Altered by Short-Term Drought Stress. FRONTIERS IN PLANT SCIENCE 2021; 11:564802. [PMID: 33519833 PMCID: PMC7838097 DOI: 10.3389/fpls.2020.564802] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 12/21/2020] [Indexed: 06/12/2023]
Abstract
Climate change is leading to increasing drought and higher temperatures, both of which reduce soil water levels and consequently water availability for plants. This reduction often induces physiological stress in plants, which in turn can affect floral development and production inducing phenotypic alterations in flowers. Because flower visitors notice and respond to small differences in floral phenotypes, changes in trait expression can alter trait-mediated flower visitor behavior. Temperature is also known to affect floral scent emission and foraging behavior and, therefore, might modulate trait-mediated flower visitor behavior. However, the link between changes in flower visitor behavior and floral traits in the context of increasing drought and temperature is still not fully understood. In a wind-tunnel experiment, we tested the behavior of 66 Bombus terrestris individuals in response to watered and drought-stressed Sinapis arvensis plants and determined whether these responses were modulated by air temperature. Further, we explored whether floral traits and drought treatment were correlated with bumblebee behavior. The initial attractiveness of drought and watered plants did not differ, as the time to first visit was similar. However, bumblebees visited watered plants more often, their visitation rate to flowers was higher on watered plants, and bumblebees stayed for longer, indicating that watered plants were more attractive for foraging. Bumblebee behavior differed between floral trait expressions, mostly independently of treatment, with larger inflorescences and flowers leading to a decrease in the time until the first flower visit and an increase in the number of visits and the flower visitation rate. Temperature modulated bumblebee activity, which was highest at 25°C; the interaction of drought/water treatment and temperature led to higher visitation rate on watered plants at 20°C, possibly as a result of higher nectar production. Thus, bumblebee behavior is influenced by the watered status of plants, and bumblebees can recognize differences in intraspecific phenotypes involving morphological traits and scent emission, despite overall morphological traits and scent emission not being clearly separated between treatments. Our results indicate that plants are able to buffer floral trait expressions against short-term drought events, potentially to maintain pollinator attraction.
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20
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Arroyo MTK, Robles V, Tamburrino Í, Martínez-Harms J, Garreaud RD, Jara-Arancio P, Pliscoff P, Copier A, Arenas J, Keymer J, Castro K. Extreme Drought Affects Visitation and Seed Set in a Plant Species in the Central Chilean Andes Heavily Dependent on Hummingbird Pollination. PLANTS (BASEL, SWITZERLAND) 2020; 9:E1553. [PMID: 33198222 PMCID: PMC7697181 DOI: 10.3390/plants9111553] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 11/07/2020] [Accepted: 11/09/2020] [Indexed: 01/19/2023]
Abstract
Rising temperatures and increasing drought in Mediterranean-type climate areas are expected to affect plant-pollinator interactions, especially in plant species with specialised pollination. Central Chile experienced a mega drought between 2010 and 2020 which reached an extreme in the austral summer of 2019-2020. Based on intensive pollinator sampling and floral studies we show that the subalpine form of Mutisia subulata (Asteraceae) is a specialised hummingbird-pollinated species. In a two-year study which included the severest drought year, we quantified visitation frequency, flower-head density, flower-head visitation rates, two measures of floral longevity, nectar characteristics and seed set and monitored climatic variables to detect direct and indirect climate-related effects on pollinator visitation. Flower-head density, nectar standing crop and seed set were significantly reduced in the severest drought year while nectar concentration increased. The best model to explain visitation frequency included flower-head density, relative humidity, temperature, and nectar standing crop with highly significant effects of the first three variables. Results for flower-head density suggest hummingbirds were able to associate visual signals with reduced resource availability and/or were less abundant. The negative effect of lower relative humidity suggests the birds were able to perceive differences in nectar concentration. Reduced seed set per flower-head together with the availability of far fewer ovules in the 2019-2020 austral summer would have resulted in a major reduction in seed set. Longer and more intense droughts in this century could threaten local population persistence in M. subulata.
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Affiliation(s)
- Mary T. K. Arroyo
- Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, 7800003 Ñuñoa, Santiago, Chile; (V.R.); (Í.T.); (A.C.); (J.A.); (J.K.); (K.C.)
- Instituto de Ecología y Biodiversidad (IEB), Las Palmeras 3425, 7800003 Ñuñoa, Santiago, Chile;
| | - Valeria Robles
- Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, 7800003 Ñuñoa, Santiago, Chile; (V.R.); (Í.T.); (A.C.); (J.A.); (J.K.); (K.C.)
- Instituto de Ecología y Biodiversidad (IEB), Las Palmeras 3425, 7800003 Ñuñoa, Santiago, Chile;
| | - Ítalo Tamburrino
- Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, 7800003 Ñuñoa, Santiago, Chile; (V.R.); (Í.T.); (A.C.); (J.A.); (J.K.); (K.C.)
- Instituto de Ecología y Biodiversidad (IEB), Las Palmeras 3425, 7800003 Ñuñoa, Santiago, Chile;
| | - Jaime Martínez-Harms
- INIA, La Cruz, Instituto de Investigaciones Agropecuarias, Chorrillos 86, 2280454 La Cruz, Chile;
| | - René D. Garreaud
- Departamento de Geofísica, Universidad de Chile, Avenida Blanco Encalada 2002, 8370449 Santiago, Chile;
- Centro de Ciencia del Clima y la Resiliencia (CR2), Avenida Blanco Encalada 2002, Universidad de Chile, 8370449 Santiago, Chile
| | - Paola Jara-Arancio
- Instituto de Ecología y Biodiversidad (IEB), Las Palmeras 3425, 7800003 Ñuñoa, Santiago, Chile;
- Departamento de Ciencias Biológicas y Departamento de Ecología y Biodiversidad, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Republica 252, 8370134 Santiago, Chile
| | - Patricio Pliscoff
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, 8331150 Santiago, Chile;
- Instituto de Geografía, Facultad de Historia, Geografía y Ciencia Política, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4860, 7820436 Macul, Santiago, Chile
| | - Ana Copier
- Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, 7800003 Ñuñoa, Santiago, Chile; (V.R.); (Í.T.); (A.C.); (J.A.); (J.K.); (K.C.)
| | - Jonás Arenas
- Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, 7800003 Ñuñoa, Santiago, Chile; (V.R.); (Í.T.); (A.C.); (J.A.); (J.K.); (K.C.)
| | - Joaquín Keymer
- Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, 7800003 Ñuñoa, Santiago, Chile; (V.R.); (Í.T.); (A.C.); (J.A.); (J.K.); (K.C.)
| | - Kiara Castro
- Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, 7800003 Ñuñoa, Santiago, Chile; (V.R.); (Í.T.); (A.C.); (J.A.); (J.K.); (K.C.)
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21
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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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22
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García M, Benítez-Vieyra S, Sérsic AN, Pauw A, Cocucci AA, Traveset A, Sazatornil F, Paiaro V. Is variation in flower shape and length among native and non-native populations of Nicotiana glauca a product of pollinator-mediated selection? Evol Ecol 2020. [DOI: 10.1007/s10682-020-10082-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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23
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Rering CC, Franco JG, Yeater KM, Mallinger RE. Drought stress alters floral volatiles and reduces floral rewards, pollinator activity, and seed set in a global plant. Ecosphere 2020. [DOI: 10.1002/ecs2.3254] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- Caitlin C. Rering
- Center for Medical, Agricultural and Veterinary Entomology USDA‐Agricultural Research Service 1700 SW 23rd Drive Gainesville Florida32608USA
| | - Jose G. Franco
- Northern Great Plains Research Laboratory USDA‐Agricultural Research Service 1701 10th Avenue SW Mandan North Dakota58554USA
- Dale Bumpers Small Farms Research Center USDA‐Agricultural Research Service 6883 South State Highway 23 Booneville Arkansas72927USA
| | - Kathleen M. Yeater
- Plains Area, Office of the Director USDA‐Agricultural Research Service 2150 Centre Avenue, Building D, Suite 300 Fort Collins Colorado80526USA
| | - Rachel E. Mallinger
- Department of Entomology and Nematology University of Florida 1881 Natural Areas Drive Gainesville Florida32611USA
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24
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Fertilizer Rate and Substrate Water Content Effect on Growth and Flowering of Beardtongue. HORTICULTURAE 2020. [DOI: 10.3390/horticulturae6030057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Research has shown that reduced irrigation and fertilizer rates can still produce good plant growth when irrigation is applied efficiently to reduce leaching. The impact of reduced irrigation and fertilizer rate on flowering and plant growth would provide additional information on the potential for reduced production inputs. The objective of this research was to quantify the impact of reduced irrigation and fertilizer rate on growth and flowering of Ruby Candle beardtongue (Penstemon × ‘Ruby Candle’). A soil moisture sensor automated irrigation system was used to maintain plants at 40% volumetric water content [VWC; well-watered (WW)] or 18% VWC (reduced irrigation, RI). A controlled release fertilizer was applied at 100%, 50%, and 25% of the bag rate (12 g/plant). There was not a significant treatment effect on any flower parameter. Average plant height was greatest for plants receiving the 50% fertilizer rate (75.9 cm) and was lowest for the 100% fertilizer rate (64.5 cm). Internode length was greater for WW plants (36.9 mm) than RI plants (32.4 mm). Well-watered plants had greater fresh weight (99.1 g) than RI plants (79.2 g) and 100% fertilizer rate (97.1 g) was greater than the 25% fertilizer rate (82.7 g).
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25
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Göttlinger T, Lohaus G. Influence of light, dark, temperature and drought on metabolite and ion composition in nectar and nectaries of an epiphytic bromeliad species (Aechmea fasciata). PLANT BIOLOGY (STUTTGART, GERMANY) 2020; 22:781-793. [PMID: 32558085 DOI: 10.1111/plb.13150] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 06/05/2020] [Indexed: 05/26/2023]
Abstract
Research into the influence of stress factors, such as drought, different temperatures and/or varied light conditions, on plants due to climate changes is becoming increasingly important. Epiphytes, like many species of the Bromeliaceae, are particularly affected by this, but little is known about impacts on nectar composition and nectary metabolism. We investigated the influence of drought, different temperatures and light-dark regimes on nectar and nectaries of the epiphytic bromeliad species, Aechmea fasciata, and also the influence of drought with the terrestrial bromeliad, Billbergia nutans. The content of sugars, amino acids and ions in nectar and nectaries was analysed using HPLC. In addition, the starch content and the activities of different invertases in nectaries were determined. Compositions of nectar and nectaries were hardly influenced, neither by light nor dark, nor by different temperatures. In contrast, drought revealed changes in nectar volumes and nectar sugar compositions in the epiphytic bromeliad as well as in the terrestrial bromeliad. In both species, the sucrose-to-hexose ratio in nectar decreased considerably during the drought period. These changes in nectar sugar composition do not correlate with changes in the nectaries. The total sugar, amino acid and ion concentrations remained constant in nectar as well as in nectaries during the drought period. Changes in nectar composition or in the production of floral pollinator rewards are likely to affect plant-pollinator interactions. It remains questionable how far the adaptations of the bromeliads to drought and diverse light or temperature conditions are still sufficient.
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Affiliation(s)
- T Göttlinger
- Molecular Plant Science and Plant Biochemistry, University of Wuppertal, Wuppertal, Germany
| | - G Lohaus
- Molecular Plant Science and Plant Biochemistry, University of Wuppertal, Wuppertal, Germany
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26
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Yang H, Wang T, Yu X, Yang Y, Wang C, Yang Q, Wang X. Enhanced sugar accumulation and regulated plant hormone signalling genes contribute to cold tolerance in hypoploid Saccharum spontaneum. BMC Genomics 2020; 21:507. [PMID: 32698760 PMCID: PMC7376677 DOI: 10.1186/s12864-020-06917-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 07/15/2020] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Wild sugarcane Saccharum spontaneum plants vary in ploidy, which complicates the utilization of its germplasm in sugarcane breeding. Investigations on cold tolerance in relation to different ploidies in S. spontaneum may promote the exploitation of its germplasm and accelerate the improvement of sugarcane varieties. RESULTS A hypoploid clone 12-23 (2n = 54) and hyperploid clone 15-28 (2n = 92) of S. spontaneum were analysed under cold stress from morphological, physiological, and transcriptomic perspectives. Compared with clone 15-28, clone 12-23 plants had lower plant height, leaf length, internode length, stem diameter, and leaf width; depressed stomata and prominent bristles and papillae; and thick leaves with higher bulliform cell groups and thicker adaxial epidermis. Compared with clone 15-28, clone 12-23 showed significantly lower electrical conductivity, significantly higher water content, soluble protein content, and superoxide dismutase activity, and significantly higher soluble sugar content and peroxidase activity. Under cold stress, the number of upregulated genes and downregulated genes of clone 12-23 was higher than clone 15-28, and many stress response genes and pathways were affected and enriched to varying degrees, particularly sugar and starch metabolic pathways and plant hormone signalling pathways. Under cold stress, the activity of 6-phosphate glucose trehalose synthase, trehalose phosphate phosphatase, and brassinosteroid-signalling kinase and the content of trehalose and brassinosteroids of clone 12-23 increased. CONCLUSIONS Compared with hyperploid clone 15-28, hypoploid clone 12-23 maintained a more robust osmotic adjustment system through sugar accumulation and hormonal regulation, which resulted in stronger cold tolerance.
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Affiliation(s)
- Hongli Yang
- Sugarcane Research Institute, Yunnan Agricultural University, Kunming, 650201, Yunnan Province, PR China
| | - Tianju Wang
- Sugarcane Research Institute, Yunnan Agricultural University, Kunming, 650201, Yunnan Province, PR China.,Chuxiong normal university, Chuxiong, 675000, Yunnan Province, PR China
| | - Xinghua Yu
- Sugarcane Research Institute, Yunnan Agricultural University, Kunming, 650201, Yunnan Province, PR China.,Wenshan Academy of Agricultural Sciences, Wenshan, 663000, Yunnan Province, PR China
| | - Yang Yang
- Sugarcane Research Institute, Yunnan Agricultural University, Kunming, 650201, Yunnan Province, PR China
| | - Chunfang Wang
- Sugarcane Research Institute, Yunnan Agricultural University, Kunming, 650201, Yunnan Province, PR China
| | - Qinghui Yang
- Sugarcane Research Institute, Yunnan Agricultural University, Kunming, 650201, Yunnan Province, PR China.
| | - Xianhong Wang
- Sugarcane Research Institute, Yunnan Agricultural University, Kunming, 650201, Yunnan Province, PR China.
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27
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Nectar shortage caused by aphids may reduce seed output via pollination interference. Oecologia 2020; 194:321-332. [PMID: 32676820 DOI: 10.1007/s00442-020-04712-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 07/11/2020] [Indexed: 01/05/2023]
Abstract
Herbivores decrease plant fitness by consuming reproductive tissues, limiting resources, and/or affecting mutualisms. Although these mechanisms were extensively tested in chewing herbivores, the impact of other functional groups (e.g., sap-feeders) remains poorly understood. We investigated whether aphids affect plant reproduction via direct resource limitation on seed production and/or pollination interference. We compared plant traits and the seed set of naturally aphid-free vs. aphid-infested plants and then manipulated aphid presence and pollen receipt. We used path models to examine the links between variables. Nectar volume and seed set of aphid-infested plants was 54% and 42% lower than that of aphid-free plants. 72 h after removing aphids, nectar volume was restored to the level of aphid-free plants. When pollinators were excluded, the seed set of aphid-infested and aphid-free plants did not differ, suggesting that direct resource limitation on seed production was not the cause of reduced plant fitness. Manual addition of pollen restored the seed set of aphid-infested plants to the level of aphid-free plants, evidencing that plants were pollen limited. The path analysis showed a negative link between aphids and the seed set via nectar volume, supporting that nectar shortage caused by aphids may interfere with pollination and reduce plant fitness. Since aphids are crop pests and feed on a large number of animal-pollinated plants, the potential of these insects to influence pollination and plant fitness is high. This study emphasizes the ecological importance of aphids and the need to better understand the links between sap-feeding herbivory, pollination, and plant fitness.
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Descamps C, Marée S, Hugon S, Quinet M, Jacquemart A. Species-specific responses to combined water stress and increasing temperatures in two bee-pollinated congeners ( Echium, Boraginaceae). Ecol Evol 2020; 10:6549-6561. [PMID: 32724532 PMCID: PMC7381579 DOI: 10.1002/ece3.6389] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 04/24/2020] [Accepted: 04/27/2020] [Indexed: 12/21/2022] Open
Abstract
Water stress and increasing temperatures are two main constraints faced by plants in the context of climate change. These constraints affect plant physiology and morphology, including phenology, floral traits, and nectar rewards, thus altering plant-pollinator interactions.We compared the abiotic stress responses of two bee-pollinated Boraginaceae species, Echium plantagineum, an annual, and Echium vulgare, a biennial. Plants were grown for 5 weeks during their flowering period under two watering regimes (well-watered and water-stressed) and three temperature regimes (21, 24, 27°C).We measured physiological traits linked to photosynthesis (chlorophyll content, stomatal conductance, and water use efficiency), and vegetative (leaf number and growth rate) and floral (e.g., flower number, phenology, floral morphology, and nectar production) traits.The physiological and morphological traits of both species were affected by the water and temperature stresses, although the effects were greater for the annual species. Both stresses negatively affected floral traits, accelerating flower phenology, decreasing flower size, and, for the annual species, decreasing nectar rewards. In both species, the number of flowers was reduced by 22%-45% under water stress, limiting the total amount of floral rewards.Under water stress and increasing temperatures, which mimic the effects of climate change, floral traits and resources of bee-pollinated species are affected and can lead to disruptions of pollination and reproductive success.
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Affiliation(s)
| | - Sophie Marée
- Earth and Life Institute–AgronomyUCLouvainLouvain‐la‐NeuveBelgium
| | - Sophie Hugon
- Earth and Life Institute–AgronomyUCLouvainLouvain‐la‐NeuveBelgium
| | - Muriel Quinet
- Earth and Life Institute–AgronomyUCLouvainLouvain‐la‐NeuveBelgium
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Peach K, Liu JW, Mazer SJ. Climate Predicts UV Floral Pattern Size, Anthocyanin Concentration, and Pollen Performance in Clarkia unguiculata. FRONTIERS IN PLANT SCIENCE 2020; 11:847. [PMID: 32612627 PMCID: PMC7308548 DOI: 10.3389/fpls.2020.00847] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 05/26/2020] [Indexed: 05/25/2023]
Abstract
Given that flower size and pigmentation can mediate plant-pollinator interactions, many studies have focused on pollinator-driven selection on these floral traits. However, abiotic factors such as precipitation, temperature, and solar radiation also contribute to geographic variation in floral color, pattern, and size within multiple species. Several studies have described an ecogeographic pattern within species in which high temperature, high ultraviolet (UV) radiation, low precipitation and/or low latitudes are associated with increased floral anthocyanin production, smaller flowers, and/or larger UV-absorbing floral patterns (nectar guides or bullseyes). However, latitude or elevation is often used as a proxy variable to study variation in floral traits associated with a wide range of climatic variables, making the proximate abiotic drivers of variation difficult to identify. In this study, we tested and corroborated several predictions for how the abiotic environment may directly or indirectly shape geographic patterns of floral color, pattern, and size in Clarkia unguiculata (Onagraceae). This study provides the first report of geographic variation in multispectral floral color and pattern in C. unguiculata, while also providing an experimental test of the putative protective role of UV absorption for pollen performance. We quantified geographic variation among greenhouse-raised populations in UV floral pattern size, mean UV petal reflectance, anthocyanin concentration, and petal area in C. unguiculata across its natural range in California and, using 30 year climate normals for each population, we identified climatic and topographic attributes that are correlated with our focal floral traits. In addition, we examined pollen performance under high and low UV light conditions to detect the protective function (if any) of UV floral patterns in this species. Contrary to our expectations, the nectar guide and the proportion of the petal occupied by the UV nectar guide were largest in low solar UV populations. Estimated floral anthocyanin concentration was highest in populations with high solar UV, which does support our predictions. The size of the UV nectar guide did not affect pollen performance in either of the light treatments used in this study. We conclude that, under the conditions examined here, UV-absorbing floral patterns do not serve a direct "pollen protection" function in C. unguiculata. Our results only partially align with expected ecogeographic patterns in these floral traits, highlighting the need for research in a wider range of taxa in order to detect and interpret broad scale patterns of floral color variation.
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Affiliation(s)
- Kristen Peach
- Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Jasen W. Liu
- Population Biology Graduate Group, University of California, Davis, Davis, CA, United States
| | - Susan J. Mazer
- Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
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Are all butterflies equal? Population-wise proboscis length variation predicts flower choice in a butterfly. Anim Behav 2020. [DOI: 10.1016/j.anbehav.2020.03.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Weber UK, Nuismer SL, Espíndola A. Patterns of floral morphology in relation to climate and floral visitors. ANNALS OF BOTANY 2020; 125:433-445. [PMID: 31650169 PMCID: PMC7061174 DOI: 10.1093/aob/mcz172] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 10/21/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND AND AIMS The diversity of floral morphology among plant species has long captured the interest of biologists and led to the development of a number of explanatory theories. Floral morphology varies substantially within species, and the mechanisms maintaining this diversity are diverse. One possibility is that spatial variation in the pollinator fauna drives the evolution of spatially divergent floral ecotypes adapted to the local suite of pollinators. Another possibility is that geographic variation in the abiotic environment and local climatic conditions favours different floral morphologies in different regions. Although both possibilities have been shown to explain floral variation in some cases, they have rarely been competed against one another using data collected from large spatial scales. In this study, we assess floral variation in relation to climate and floral visitors in four oil-reward-specialized pollination interactions. METHODS We used a combination of large-scale plant and pollinator samplings, morphological measures and climatic data. We analysed the data using spatial approaches, as well as traditional multivariate and structural equation modelling approaches. KEY RESULTS Our results indicate that the four species have different levels of specialization, and that this can be explained by their climatic niche breadth. In addition, our results show that, at least for some species, floral morphology can be explained by the identity of floral visitors, with climate having only an indirect effect. CONCLUSIONS Our results demonstrate that, even in very specialized interactions, both biotic and abiotic variables can explain a substantial amount of intraspecific variation in floral morphology.
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Affiliation(s)
- Urs K Weber
- Department of Entomology, Plant Sciences Building 3138, 4291 Fieldhouse Dr., University of Maryland, College Park, MD, USA
| | - Scott L Nuismer
- Department of Biological Sciences, 875 Perimeter Dr. MS 3051, University of Idaho, Moscow, ID, USA
| | - Anahí Espíndola
- Department of Entomology, Plant Sciences Building 3138, 4291 Fieldhouse Dr., University of Maryland, College Park, MD, USA
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Suni SS, Ainsworth B, Hopkins R. Local adaptation mediates floral responses to water limitation in an annual wildflower. AMERICAN JOURNAL OF BOTANY 2020; 107:209-218. [PMID: 32080832 DOI: 10.1002/ajb2.1434] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 11/07/2019] [Indexed: 05/22/2023]
Abstract
PREMISE Understanding how environmental stress affects the strength of mutualisms is critically important given observed and projected environmental changes. In particular, the frequency and duration of drought have been increasing worldwide. We investigated how water availability affects plant traits that mediate a pollination mutualism. METHODS For butterfly-pollinated Phlox drummondii, we determined how moisture availability affects flower size, nectar volume, and nectar sugar amount. Furthermore, we explored the role that local adaptation may play in responses to moisture availability by including plants collected from regions that differ in aridity. Finally, we determined whether responses of plant populations to selection may differ under drought by calculating heritability of traits under control and dry conditions. RESULTS Flower size was generally smaller in dry plants than in control plants. Early in the treatment period, nectar volume and sugar were higher in dry plants than in control plants for plants from both arid and wetter regions. With prolonged dry treatment, nectar volume and sugar remained higher only in plants from the arid region. Heritability of floral traits was lower for water-limited plants than for control plants. CONCLUSIONS Plant investment into pollination mutualisms under environmental stress may depend on the extent to which populations are already locally adapted to such conditions, suggesting that mutualism may remain strong, at least in arid regions. However, decreases in heritability under water-limitation suggest that responses to selection imposed by pollinators may be low, even if drought-adapted plants maintain production of rewards to pollinators.
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Affiliation(s)
- Sevan S Suni
- The Arnold Arboretum of Harvard University, 1300 Centre Street, Boston, MA, 02131, USA
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
- Department of Biology, University of San Francisco, 2130 Fulton Street, San Francisco, CA, 94117, USA
| | - Benjamin Ainsworth
- The Arnold Arboretum of Harvard University, 1300 Centre Street, Boston, MA, 02131, USA
| | - Robin Hopkins
- The Arnold Arboretum of Harvard University, 1300 Centre Street, Boston, MA, 02131, USA
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
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Patterson TA, Grundel R, Dzurisin JDK, Knutson RL, Hellmann JJ. Evidence of an extreme weather‐induced phenological mismatch and a local extirpation of the endangered Karner blue butterfly. CONSERVATION SCIENCE AND PRACTICE 2019. [DOI: 10.1111/csp2.147] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Affiliation(s)
| | - Ralph Grundel
- Great Lakes Science Center, U.S. Geological Survey Chesterton Indiana
| | - Jason D. K. Dzurisin
- Center for Environmental Management of Military Lands, Colorado State University Fort Collins Colorado
| | - Randy L. Knutson
- National Park Service, Indiana Dunes National Park Porter Indiana
| | - Jessica J. Hellmann
- Department of Ecology, Evolution and BehaviorUniversity of Minnesota St. Paul Minnesota
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Razanajatovo M, Fischer L, van Kleunen M. Do floral traits and the selfing capacity of Mimulus guttatus plastically respond to experimental temperature changes? Oecologia 2019; 192:261-272. [PMID: 31760481 DOI: 10.1007/s00442-019-04558-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 11/11/2019] [Indexed: 01/08/2023]
Abstract
Climate change can negatively impact plant-pollinator interactions, and reduce outcross pollination. For reproductive assurance, an increased capacity for autonomous selfing should benefit the persistence of plants under new temperature conditions. Plastic responses of the autonomous selfing capacity to climate change may occur indirectly due to changes in floral traits associated with this capacity. We tested whether the mixed mating plant Mimulus guttatus is capable of plastic changes in floral traits favoring autonomous selfing in response to temperature changes. In seven growth chambers, we grew M. guttatus originating from a large range of latitudes (from 37.89° N to 49.95° N) and thus home temperatures in North America, and experimentally assessed the (autonomous) selfing and outcrossing capacities of the plants. With an increase in the difference between the overall mean daytime and nighttime experimental test temperature and home temperature, flower length and width decreased. The plastic response in flower size suggests that plants may be more successful at autonomous selfing. However, we did not find direct evidence that M. guttatus responded to increased temperature by an increased autonomous selfing capacity. With an increase in temperature difference, the odds of seed production, number of seeds, and individual seed mass decreased. Our results indicate that global warming and the associated increase in extreme temperature events may be detrimental to the reproduction and thus persistence of some plants.
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Affiliation(s)
- Mialy Razanajatovo
- Ecology, Department of Biology, University of Konstanz, Universitätsstrasse 10, 78457, Constance, Germany.
| | - Liliana Fischer
- Ecology, Department of Biology, University of Konstanz, Universitätsstrasse 10, 78457, Constance, Germany
| | - Mark van Kleunen
- Ecology, Department of Biology, University of Konstanz, Universitätsstrasse 10, 78457, Constance, Germany.,Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, Taizhou University, Taizhou, 318000, China
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Theron GL, de Waal C, Barrett SCH, Anderson B. Geographic variation of reproductive traits and competition for pollinators in a bird-pollinated plant. Ecol Evol 2019; 9:10122-10134. [PMID: 31673331 PMCID: PMC6816071 DOI: 10.1002/ece3.5457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 04/25/2019] [Accepted: 05/28/2019] [Indexed: 11/19/2022] Open
Abstract
Geographic variation in the reproductive traits of animal-pollinated plants can be shaped by spatially variable selection imposed by differences in the local pollination environment. We investigated this process in Babiana ringens (Iridaceae), an enigmatic species from the Western Cape region of South Africa. B. ringens has evolved a specialized perch facilitating cross-pollination by sunbirds and displays striking geographic variation in perch size and floral traits. Here, we investigate whether this variation can be explained by geographic differences in the pollinator communities. We measured floral and inflorescence traits, and abiotic variables (N, P, C, and rainfall) and made observations of sunbirds in populations spanning the range of B. ringens. In each population, we recorded sunbird species identity and measured visitation rates, interfloral pollen transfer, and whether the seed set of flowers was pollen limited. To evaluate whether competition from co-occurring sunbird-pollinated species might reduce visitation, we quantified nectar rewards in B. ringens and of other co-flowering bird-pollinated species in local communities in which populations occurred. Variation in abiotic variables was not associated with geographical variation of traits in B. ringens. Malachite sunbirds were the dominant visitor (97% of visits) and populations with larger-sized traits exhibited higher visitation rates, more between-flower pollen transfer and set more seed. No sunbirds were observed in four populations, all with smaller-sized traits. Sunbird visitation to B. ringens was not associated with local sunbird activity in communities, but sunbird visitation was negatively associated with the amount of B. ringens sugar relative to the availability of alternative nectar sources. Our study provides evidence that B. ringens populations with larger floral traits are visited more frequently by sunbirds, and we propose that visitation rates to B. ringens may be influenced, in part, by competition with other sunbird-pollinated species.
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Affiliation(s)
- Genevieve L. Theron
- Department of Botany and ZoologyStellenbosch UniversityMatielandSouth Africa
| | - Caroli de Waal
- Department of Botany and ZoologyStellenbosch UniversityMatielandSouth Africa
| | | | - Bruce Anderson
- Department of Botany and ZoologyStellenbosch UniversityMatielandSouth Africa
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36
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Burkle LA, Simanonok MP, Durney JS, Myers JA, Belote RT. Wildfires Influence Abundance, Diversity, and Intraspecific and Interspecific Trait Variation of Native Bees and Flowering Plants Across Burned and Unburned Landscapes. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00252] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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37
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Ferguson L, Beckett N, French MC, Campbell M, Smith T, Adamo S. Sugar intake interacts with temperature to influence reproduction and immunity in adult Culex pipiens mosquitoes. CAN J ZOOL 2019. [DOI: 10.1139/cjz-2018-0129] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Disease transmission by insect vectors will depend on integrated physiological responses to interacting environmental variables. We explored how interactions between temperature and sucrose concentration affected immunity and fecundity, two variables that contribute to vectorial capacity, in Culex pipiens Linnaeus, 1758 mosquitoes. We provided female C. pipiens with either 2% or 20% sucrose and exposed them to low (22 °C), moderate (25 °C), or high (30 °C) temperatures for 8 days. We then measured the strength of the melanization response in one subpopulation of females and the number of eggs laid as a measure of fecundity in another subpopulation. Temperature interacted with diet to weaken immunity under 2% sucrose at 22 and 25 °C. This effect disappeared at 30 °C, suggesting that high temperatures allowed mosquitoes to compensate for the effects of decreased sucrose. Conversely, increasing temperature increased egg production on a diet of 20% sucrose, but heat exposure on a diet of 2% sucrose decreased fecundity. Overall, we suggest that heat exposure requires investment in thermal protection, which may prompt reconfiguration of the immune system and (or) decreased investment in reproduction. Thus, our understanding of the effects of climate change rest on which physiological system we measure and under which combinations of stressors.
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Affiliation(s)
- L.V. Ferguson
- Department of Biology, Acadia University, Wolfville, NS B4P 2R6, Canada
| | - N.H. Beckett
- Department of Biology, Acadia University, Wolfville, NS B4P 2R6, Canada
| | - M.-C. French
- Department of Biology, Acadia University, Wolfville, NS B4P 2R6, Canada
| | - M.J. Campbell
- Department of Biology, Acadia University, Wolfville, NS B4P 2R6, Canada
| | - T.G. Smith
- Department of Biology, Acadia University, Wolfville, NS B4P 2R6, Canada
| | - S.A. Adamo
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS B3H 4R2, Canada
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Campbell DR, Sosenski P, Raguso RA. Phenotypic plasticity of floral volatiles in response to increasing drought stress. ANNALS OF BOTANY 2019; 123:601-610. [PMID: 30364929 PMCID: PMC6417471 DOI: 10.1093/aob/mcy193] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 10/04/2018] [Indexed: 05/20/2023]
Abstract
BACKGROUND AND AIMS Flowers emit a wide range of volatile compounds which can be critically important to interactions with pollinators or herbivores. Yet most studies of how the environment influences plant volatiles focus on leaf emissions, with little known about abiotic sources of variation in floral volatiles. Understanding phenotypic plasticity in floral volatile emissions has become increasingly important with globally increasing temperatures and changes in drought frequency and severity. Here quantitative relationships of floral volatile emissions to soil water content were analysed. METHODS Plants of the sub-alpine herb Ipomopsis aggregata and hybrids with its closest congener were subjected to a progressive dry down, mimicking the range of soil moistures experienced in the field. Floral volatiles and leaf gas exchange were measured at four time points during the drought. KEY RESULTS As the soil dried, floral volatile emissions increased overall and changed in composition, from more 1,3-octadiene and benzyl alcohol to higher representation of some terpenes. Emissions of individual compounds were not linearly related to volumetric water content in the soil. The dominant compound, the monoterpene α-pinene, made up the highest percentage of the scent mixture when soil moisture was intermediate. In contrast, emission of the sesquiterpene (E,E)-α-farnesene accelerated as the drought became more intense. Changes in floral volatiles did not track the time course of changes in photosynthetic rate or stomatal conductance. CONCLUSIONS This study shows responses of specific floral volatile organic compounds to soil moisture. The non-linear responses furthermore suggest that extreme droughts may have impacts that are not predictable from milder droughts. Floral volatiles are likely to change seasonally with early summer droughts in the Rocky Mountains, as well as over years as snowmelt becomes progressively earlier. Changes in water availability may have impacts on plant-animal interactions that are mediated through non-linear changes in floral volatiles.
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Affiliation(s)
- Diane R Campbell
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA, USA
- Rocky Mountain Biological Laboratory, Crested Butte, CO, USA
- For correspondence. E-mail
| | - Paula Sosenski
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA, USA
- Rocky Mountain Biological Laboratory, Crested Butte, CO, USA
- CONACYT – Departamento de Ecología Tropical, Campus de Ciencias Biológicas y Agropecuarias, Universidad Autónoma de Yucatán, Mérida, Yucatán, México
| | - Robert A Raguso
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, USA
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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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40
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Caruso CM, Eisen KE, Martin RA, Sletvold N. A meta-analysis of the agents of selection on floral traits. Evolution 2018; 73:4-14. [PMID: 30411337 DOI: 10.1111/evo.13639] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 10/23/2018] [Accepted: 10/24/2018] [Indexed: 01/03/2023]
Abstract
Floral traits are hypothesized to evolve primarily in response to selection by pollinators. However, selection can also be mediated by other environmental factors. To understand the relative importance of pollinator-mediated selection and its variation among trait and pollinator types, we analyzed directional selection gradients on floral traits from experiments that manipulated the environment to identify agents of selection. Pollinator-mediated selection was stronger than selection by other biotic factors (e.g., herbivores), but similar in strength to selection by abiotic factors (e.g., soil water), providing partial support for the hypothesis that floral traits evolve primarily in response to pollinators. Pollinator-mediated selection was stronger on pollination efficiency traits than on other trait types, as expected if efficiency traits affect fitness via interactions with pollinators, but other trait types also affect fitness via other environmental factors. In addition to varying among trait types, pollinator-mediated selection varied among pollinator taxa: selection was stronger when bees, long-tongued flies, or birds were the primary visitors than when the primary visitors were Lepidoptera or multiple animal taxa. Finally, reducing pollinator access to flowers had a relatively small effect on selection on floral traits, suggesting that anthropogenic declines in pollinator populations would initially have modest effects on floral evolution.
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Affiliation(s)
- Christina M Caruso
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Katherine E Eisen
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada.,Current Address: Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, 14853
| | - Ryan A Martin
- Department of Biology, Case Western Reserve University, Cleveland, Ohio, 44106
| | - Nina Sletvold
- Department of Ecology and Genetics, Uppsala University, Uppsala, 751 05, Sweden
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41
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Glenny WR, Runyon JB, Burkle LA. Drought and increased CO 2 alter floral visual and olfactory traits with context-dependent effects on pollinator visitation. THE NEW PHYTOLOGIST 2018; 220:785-798. [PMID: 29575008 DOI: 10.1111/nph.15081] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 02/05/2018] [Indexed: 05/10/2023]
Abstract
Climate change can alter species interactions essential for maintaining biodiversity and ecosystem function, such as pollination. Understanding the interactive effects of multiple abiotic conditions on floral traits and pollinator visitation are important to anticipate the implications of climate change on pollinator services. Floral visual and olfactory traits were measured from individuals of four forb species subjected to drought or normal water availability, and elevated or ambient concentrations of CO2 in a factorial design. Pollinator visitation rates and community composition were observed in single-species and multi-species forb assemblages. Drought decreased floral visual traits and pollinator visitation rates but increased volatile organic compound (VOC) emissions, whereas elevated CO2 positively affected floral visual traits, VOC emissions and pollinator visitation rates. There was little evidence of interactive effects of drought and CO2 on floral traits and pollinator visitation. Interestingly, the effects of climate treatments on pollinator visitation depended on whether plants were in single- or multi-species assemblages. Components of climate change altered floral traits and pollinator visitation, but effects were modulated by plant community context. Investigating the response of floral traits, including VOCs, and context-dependency of pollinator attraction provides additional insights and may aid in understanding the overall effects of climate change on plant-pollinator interactions.
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Affiliation(s)
- William R Glenny
- Department of Ecology, Montana State University, Bozeman, MT, 59717, USA
| | - Justin B Runyon
- Rocky Mountain Research Station, USDA Forest Service, Bozeman, MT, 59717, USA
| | - Laura A Burkle
- Department of Ecology, Montana State University, Bozeman, MT, 59717, USA
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Phillips BB, Shaw RF, Holland MJ, Fry EL, Bardgett RD, Bullock JM, Osborne JL. Drought reduces floral resources for pollinators. GLOBAL CHANGE BIOLOGY 2018; 24:3226-3235. [PMID: 29652102 DOI: 10.1111/gcb.14130] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Revised: 11/18/2017] [Accepted: 03/09/2018] [Indexed: 05/23/2023]
Abstract
Climate change is predicted to result in increased occurrence and intensity of drought in many regions worldwide. By increasing plant physiological stress, drought is likely to affect the floral resources (flowers, nectar and pollen) that are available to pollinators. However, little is known about impacts of drought at the community level, nor whether plant community functional composition influences these impacts. To address these knowledge gaps, we investigated the impacts of drought on floral resources in calcareous grassland. Drought was simulated using rain shelters and the impacts were explored at multiple scales and on four different experimental plant communities varying in functional trait composition. First, we investigated the effects of drought on nectar production of three common wildflower species (Lathyrus pratensis, Onobrychis viciifolia and Prunella vulgaris). In the drought treatment, L. pratensis and P. vulgaris had a lower proportion of flowers containing nectar and O. viciifolia had fewer flowers per raceme. Second, we measured the effects of drought on the diversity and abundance of floral resources across plant communities. Drought reduced the abundance of floral units for all plant communities, irrespective of functional composition, and reduced floral species richness for two of the communities. Functional diversity did not confer greater resistance to drought in terms of maintaining floral resources, probably because the effects of drought were ubiquitous across component plant communities. The findings indicate that drought has a substantial impact on the availability of floral resources in calcareous grassland, which will have consequences for pollinator behaviour and populations.
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Affiliation(s)
- Benjamin B Phillips
- Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall, UK
| | - Rosalind F Shaw
- Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall, UK
| | - Matthew J Holland
- Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall, UK
| | - Ellen L Fry
- School of Earth and Environmental Sciences, The University of Manchester, Manchester, UK
| | - Richard D Bardgett
- School of Earth and Environmental Sciences, The University of Manchester, Manchester, UK
| | - James M Bullock
- NERC Centre for Ecology and Hydrology, Wallingford, Oxfordshire, UK
| | - Juliet L Osborne
- Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall, UK
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Takkis K, Tscheulin T, Petanidou T. Differential Effects of Climate Warming on the Nectar Secretion of Early- and Late-Flowering Mediterranean Plants. FRONTIERS IN PLANT SCIENCE 2018; 9:874. [PMID: 29997639 PMCID: PMC6030359 DOI: 10.3389/fpls.2018.00874] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 06/05/2018] [Indexed: 05/27/2023]
Abstract
Floral nectar is a vital resource for pollinators, thus having a very important role in ecosystem functioning. Ongoing climate warming could have a negative effect on nectar secretion, particularly in the Mediterranean, where a strong temperature rise is expected. In turn, decreased nectar secretion, together with shifts in flowering phenology can disrupt plant-pollinator interactions and consequently affect the entire ecosystem. Under fully controlled conditions, we tested how temperature influenced nectar secretion (through nectar volume, sugar concentration, sugar content, and number of flowers produced) in six Mediterranean plant species flowering from winter to summer (viz. Asphodelus ramosus, Ballota acetabulosa, Echium plantagineum, Lavandula stoechas, Rosmarinus officinalis, and Teucrium divaricatum). We compared the changes in nectar secretion under temperatures expected by the end of the century and estimated the effect of climate warming on nectar secretion of plants flowering in different seasons. We found a significant effect of temperature on nectar secretion, with a negative effect of very high temperatures in all species. Optimal temperatures for nectar secretion were similar to the mean temperatures in the recent past (1958-2001) during the respective flowering time of each species. Increasing temperatures, however, will affect differently the early-flowering (blooming in winter and early spring) and late-flowering species (blooming in late spring and early summer). Temperature rise expected by the end of the century will shift the average temperature beyond the optimal range for flower production and the sugar produced per plant in late-flowering species. Therefore, we expect a future decrease in nectar secretion of late-flowering species, which could reduce the amount of nectar resources available for their pollinators. Early-flowering plants will be less affected (optimal temperatures were not significantly different from the future projected temperatures), and may in some cases even benefit from rising temperatures. However, as many earlier studies have found that early-flowering species are more prone to shifts in phenology, the plant-pollinator interactions could instead become affected in a different manner. Consequently, climate warming will likely have a distinctive effect on both plant and pollinator populations and their interactions across different seasons.
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Block PD, Rakotonasolo F, Ntore S, Sylvain G. Razafimandimbison, Janssens S. Four new endemic genera of Rubiaceae (Pavetteae) from Madagascar represent multiple radiations into drylands. PHYTOKEYS 2018; 99:1-66. [PMID: 29861651 PMCID: PMC5972148 DOI: 10.3897/phytokeys.99.23713] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 04/24/2018] [Indexed: 10/29/2023]
Abstract
The taxonomic positions and phylogenetic relationships of six Pavetteae species endemic to Madagascar were tested with a phylogenetic study of the Afro-Madagascan representatives of the tribe Pavetteae based on sequence data from six markers rps16, trnT-F, petD, accD-psa1, PI and ITS. The six species were resolved into four well-supported and morphologically distinct clades which we here formally recognise at generic level. The new genera are the monospecific Exallosperma and Pseudocoptosperma, each with a single species, and Helictosperma and Tulearia, each with two species. Each genus is characterised by one or more autapomorphies or by a unique combination of plesiomorphic characters. Mostly, the distinguishing characters are found in fruit and seed; Exallosperma differs from all other Pavetteae genera by the fruit consisting of two stony pyrenes, each with a single laterally flattened seed with irregularly distributed ridges on the surface; Helictosperma is unique by its single spherical seed rolled-in on itself in the shape of a giant pill-millipede. Pseudocoptosperma is characterised by the combination of three ovules pendulous from a small placenta and triangular stipules with a strongly developed awn, whereas Tulearia is characterised by robust sericeous flowers, small leaves, uni- or pauciflorous inflorescences and fruits with two pyrenes, each with a single ruminate seed. The four new genera show marked adaptations to the dry habitats in which they grow. They represent multiple radiations into drylands and highlight the importance of the dry forest and scrub vegetation in western, southern and northern Madagascar for plant biodiversity. The description of the four new genera shows that the tribe Pavetteae exhibits the same pattern as many plant groups in Madagascar, which are characterised by a high proportion of endemic genera comprising a single or a few species. In the four new genera, five new species are described and one new combination is made: Exallosperma longiflora De Block; Helictosperma malacophylla (Drake) De Block, Helictosperma poissoniana De Block, Pseudocoptosperma menabense Capuron ex De Block; Tulearia capsaintemariensis De Block and Tulearia splendida De Block.
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Affiliation(s)
- Petra De Block
- Botanic Garden Meise, Nieuwelaan 38, 1860 Meise, Belgium
| | - Franck Rakotonasolo
- Kew Madagascar Conservation Centre, Lot II J 131 Ambodivoanjo, Ivandry, Antananarivo, Madagascar
- Parc Botanique et Zoologique de Tsimbazaza, Antananarivo-101, Madagascar
| | - Salvator Ntore
- Botanic Garden Meise, Nieuwelaan 38, 1860 Meise, Belgium
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Dehydration prompts increased activity and blood feeding by mosquitoes. Sci Rep 2018; 8:6804. [PMID: 29717151 PMCID: PMC5931509 DOI: 10.1038/s41598-018-24893-z] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 04/11/2018] [Indexed: 11/27/2022] Open
Abstract
Current insights into the mosquito dehydration response rely on studies that examine specific responses but ultimately fail to provide an encompassing view of mosquito biology. Here, we examined underlying changes in the biology of mosquitoes associated with dehydration. Specifically, we show that dehydration increases blood feeding in the northern house mosquito, Culex pipiens, which was the result of both higher activity and a greater tendency to land on a host. Similar observations were noted for Aedes aegypti and Anopheles quadrimaculatus. RNA-seq and metabolome analyses in C. pipiens following dehydration revealed that factors associated with carbohydrate metabolism are altered, specifically the breakdown of trehalose. Suppression of trehalose breakdown in C. pipiens by RNA interference reduced phenotypes associated with lower hydration levels. Lastly, mesocosm studies for C. pipiens confirmed that dehydrated mosquitoes were more likely to host feed under ecologically relevant conditions. Disease modeling indicates dehydration bouts will likely enhance viral transmission. This dehydration-induced increase in blood feeding is therefore likely to occur regularly and intensify during periods when availability of water is low.
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46
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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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47
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Descamps C, Quinet M, Baijot A, Jacquemart AL. Temperature and water stress affect plant-pollinator interactions in Borago officinalis (Boraginaceae). Ecol Evol 2018; 8:3443-3456. [PMID: 29607037 PMCID: PMC5869376 DOI: 10.1002/ece3.3914] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 01/03/2018] [Accepted: 01/14/2018] [Indexed: 01/23/2023] Open
Abstract
Climate change alters the abiotic constraints faced by plants, including increasing temperature and water stress. These changes may affect flower development and production of flower rewards, thus altering plant–pollinator interactions. Here, we investigated the consequences of increased temperature and water stress on plant growth, floral biology, flower‐reward production, and insect visitation of a widespread bee‐visited species, Borago officinalis. Plants were grown for 5 weeks under three temperature regimes (21, 24, and 27°C) and two watering regimes (well‐watered and water‐stressed). Plant growth was more affected by temperature rise than water stress, and the reproductive growth was affected by both stresses. Vegetative traits were stimulated at 24°C, but impaired at 27°C. Flower development was mainly affected by water stress, which decreased flower number (15 ± 2 flowers/plant in well‐watered plants vs. 8 ± 1 flowers/plant under water stress). Flowers had a reduced corolla surface under temperature rise and water stress (3.8 ± 0.5 cm2 in well‐watered plants at 21°C vs. 2.2 ± 0.1 cm2 in water‐stressed plants at 27°C). Both constraints reduced flower‐reward production. Nectar sugar content decreased from 3.9 ± 0.3 mg/flower in the well‐watered plants at 21°C to 1.3 ± 0.4 mg/flower in the water‐stressed plants at 27°C. Total pollen quantity was not affected, but pollen viability decreased from 79 ± 4% in the well‐watered plants at 21°C to 25 ± 9% in the water‐stressed plants at 27°C. Flowers in the well‐watered plants at 21°C received at least twice as many bumblebee visits compared with the other treatments. In conclusion, floral modifications induced by abiotic stresses related to climate change affect insect behavior and alter plant–pollinator interactions.
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Affiliation(s)
- Charlotte Descamps
- Research Group « Genetics, Reproduction, Populations », Earth and Life Institute-Agronomy Université catholique de Louvain Louvain-la-Neuve Belgium
| | - Muriel Quinet
- Research Group « Genetics, Reproduction, Populations », Earth and Life Institute-Agronomy Université catholique de Louvain Louvain-la-Neuve Belgium
| | - Aurélie Baijot
- Research Group « Genetics, Reproduction, Populations », Earth and Life Institute-Agronomy Université catholique de Louvain Louvain-la-Neuve Belgium
| | - Anne-Laure Jacquemart
- Research Group « Genetics, Reproduction, Populations », Earth and Life Institute-Agronomy Université catholique de Louvain Louvain-la-Neuve Belgium
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48
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Pardee GL, Inouye DW, Irwin RE. Direct and indirect effects of episodic frost on plant growth and reproduction in subalpine wildflowers. GLOBAL CHANGE BIOLOGY 2018; 24:848-857. [PMID: 28805338 DOI: 10.1111/gcb.13865] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2017] [Accepted: 07/31/2017] [Indexed: 06/07/2023]
Abstract
Frost is an important episodic event that damages plant tissues through the formation of ice crystals at or below freezing temperatures. In montane regions, where climate change is expected to cause earlier snow melt but may not change the last frost-free day of the year, plants that bud earlier might be directly impacted by frost through damage to flower buds and reproductive structures. However, the indirect effects of frost mediated through changes in plant-pollinator interactions have rarely been explored. We examined the direct and pollinator-mediated indirect effects of frost on three wildflower species in southwestern Colorado, USA, Delphinium barbeyi (Ranunculaceae), Erigeron speciosus (Asteraceae), and Polemonium foliosissimum (Polemoniaceae), by simulating moderate (-1 to -5°C) frost events in early spring in plants in situ. Subsequently, we measured plant growth, and upon flowering measured flower morphology and phenology. Throughout the flowering season, we monitored pollinator visitation and collected seeds to measure plant reproduction. We found that frost had species-specific direct and indirect effects. Frost had direct effects on two of the three species. Frost significantly reduced flower size, total flowers produced, and seed production of Erigeron. Furthermore, frost reduced aboveground plant survival and seed production for Polemonium. However, we found no direct effects of frost on Delphinium. When we considered the indirect impacts of frost mediated through changes in pollinator visitation, one species, Erigeron, incurred indirect, negative effects of frost on plant reproduction through changes in floral traits and pollinator visitation, along with direct effects. Overall, we found that flowering plants exhibited species-specific direct and pollinator-mediated indirect responses to frost, thus suggesting that frost may play an important role in affecting plant communities under climate change.
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Affiliation(s)
- Gabriella L Pardee
- Department of Applied Ecology, North Carolina State University, Raleigh, NC, USA
- Rocky Mountain Biological Laboratory, Gothic, CO, USA
| | - David W Inouye
- Rocky Mountain Biological Laboratory, Gothic, CO, USA
- Department of Biology, University of Maryland, College Park, MD, USA
| | - Rebecca E Irwin
- Department of Applied Ecology, North Carolina State University, Raleigh, NC, USA
- Rocky Mountain Biological Laboratory, Gothic, CO, USA
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49
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Roy R, Schmitt AJ, Thomas JB, Carter CJ. Review: Nectar biology: From molecules to ecosystems. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2017; 262:148-164. [PMID: 28716410 DOI: 10.1016/j.plantsci.2017.04.012] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 04/17/2017] [Accepted: 04/19/2017] [Indexed: 05/06/2023]
Abstract
Plants attract mutualistic animals by offering a reward of nectar. Specifically, floral nectar (FN) is produced to attract pollinators, whereas extrafloral nectar (EFN) mediates indirect defenses through the attraction of mutualist predatory insects to limit herbivory. Nearly 90% of all plant species, including 75% of domesticated crops, benefit from animal-mediated pollination, which is largely facilitated by FN. Moreover, EFN represents one of the few defense mechanisms for which stable effects on plant health and fitness have been demonstrated in multiple systems, and thus plays a crucial role in the resistance phenotype of plants producing it. In spite of its central role in plant-animal interactions, the molecular events involved in the development of both floral and extrafloral nectaries (the glands that produce nectar), as well as the synthesis and secretion of the nectar itself, have been poorly understood until recently. This review will cover major recent developments in the understanding of (1) nectar chemistry and its role in plant-mutualist interactions, (2) the structure and development of nectaries, (3) nectar production, and (4) its regulation by phytohormones.
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Affiliation(s)
- Rahul Roy
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, MN 55108, USA
| | - Anthony J Schmitt
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, MN 55108, USA
| | - Jason B Thomas
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, MN 55108, USA
| | - Clay J Carter
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, MN 55108, USA.
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50
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Brock MT, Winkelman RL, Rubin MJ, Edwards CE, Ewers BE, Weinig C. Allocation to male vs female floral function varies by currency and responds differentially to density and moisture stress. Heredity (Edinb) 2017; 119:349-359. [PMID: 28767102 DOI: 10.1038/hdy.2017.41] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 05/30/2017] [Accepted: 05/31/2017] [Indexed: 01/29/2023] Open
Abstract
Allocation of finite resources to separate reproductive functions is predicted to vary across environments and affect fitness. Biomass is the most commonly measured allocation currency; however, in comparison with nutrients it may be less limited and express different environmental and evolutionary responses. Here, we measured carbon, nitrogen, phosphorus, and biomass allocation among floral whorls in recombinant inbred lines of Brassica rapa in multiple environments to characterize the genetic architecture of floral allocation, including its sensitivity to environmental heterogeneity and to choice of currency. Mass, carbon, and nitrogen allocation to female whorls (pistils and sepals) decreased under high density, whereas nitrogen allocation to male organs (stamens) decreased under drought. Phosphorus allocation decreased by half in pistils under drought, while stamen phosphorus was unaffected by environment. While the contents of each currency were positively correlated among whorls, selection to improve fitness through female (or male) function typically favored increased allocation to pistils (or stamens) but decreased allocation to other whorls. Finally, genomic regions underlying correlations among allocation metrics were mapped, and loci related to nitrogen uptake and floral organ development were located within mapped quantitative trait loci. Our candidate gene identification suggests that nutrient uptake may be a limiting step in maintaining male allocation. Taken together, allocation to male vs female function is sensitive to distinct environmental stresses, and the choice of currency affects the interpretation of floral allocation responses to the environment. Further, genetic correlations may counter the evolution of allocation patterns that optimize fitness through female or male function.
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Affiliation(s)
- M T Brock
- Department of Botany, University of Wyoming, Laramie, WY, USA
| | - R L Winkelman
- Department of Botany, University of Wyoming, Laramie, WY, USA
| | - M J Rubin
- Department of Botany, University of Wyoming, Laramie, WY, USA.,Program in Ecology, University of Wyoming, Laramie, WY, USA
| | - C E Edwards
- Department of Botany, University of Wyoming, Laramie, WY, USA.,Center for Conservation and Sustainable Development, Missouri Botanical Garden, St Louis, MO, USA
| | - B E Ewers
- Department of Botany, University of Wyoming, Laramie, WY, USA.,Program in Ecology, University of Wyoming, Laramie, WY, USA
| | - C Weinig
- Department of Botany, University of Wyoming, Laramie, WY, USA.,Program in Ecology, University of Wyoming, Laramie, WY, USA.,Department of Molecular Biology, University of Wyoming, Laramie, WY, USA
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