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Heuel KC, Haßlberger TA, Ayasse M, Burger H. Floral Trait Preferences of Three Common wild Bee Species. INSECTS 2024; 15:427. [PMID: 38921142 PMCID: PMC11203783 DOI: 10.3390/insects15060427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Accepted: 06/01/2024] [Indexed: 06/27/2024]
Abstract
The interaction between bees and flowering plants is mediated by floral cues that enable bees to find foraging plants. We tested floral cue preferences among three common wild bee species: Lasioglossum villosulum, Osmia bicornis, and Bombus terrestris. Preferences are well studied in eusocial bees but almost unknown in solitary or non-eusocial generalist bee species. Using standardized artificial flowers altered in single cues, we tested preferences for color hue, achromatic contrast, scent complexity, corolla size, and flower depth. We found common attractive cues among all tested bees. Intensively colored flowers and large floral displays were highly attractive. No preferences were observed in scent complexity experiments, and the number of volatiles did not influence the behavior of bees. Differing preferences were found for color hue. The specific behaviors were probably influenced by foraging experience and depended on the flower choice preferences of the tested bee species. In experiments testing different flower depths of reward presentation, the bees chose flat flowers that afforded low energy costs. The results reveal that generalist wild bee species other than well-studied honeybees and bumblebees show strong preferences for distinct floral cues to find potential host plants. The diverse preferences of wild bees ensure the pollination of various flowering plants.
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Affiliation(s)
- Kim C. Heuel
- Institute for Evolutionary Ecology and Conservation Genomics, University of Ulm, 89077 Ulm, Germany (M.A.); (H.B.)
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Wong DCJ, Wang Z, Perkins J, Jin X, Marsh GE, John EG, Peakall R. The road less taken: Dihydroflavonol 4-reductase inactivation and delphinidin anthocyanin loss underpins a natural intraspecific flower colour variation. Mol Ecol 2024:e17334. [PMID: 38651763 DOI: 10.1111/mec.17334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 02/22/2024] [Accepted: 03/20/2024] [Indexed: 04/25/2024]
Abstract
Visual cues are of critical importance for the attraction of animal pollinators, however, little is known about the molecular mechanisms underpinning intraspecific floral colour variation. Here, we combined comparative spectral analysis, targeted metabolite profiling, multi-tissue transcriptomics, differential gene expression, sequence analysis and functional analysis to investigate a bee-pollinated orchid species, Glossodia major with common purple- and infrequent white-flowered morphs. We found uncommon and previously unreported delphinidin-based anthocyanins responsible for the conspicuous and pollinator-perceivable colour of the purple morph and three genetic changes underpinning the loss of colour in the white morph - (1) a loss-of-function (LOF; frameshift) mutation affecting dihydroflavonol 4-reductase (DFR1) coding sequence due to a unique 4-bp insertion, (2) specific downregulation of functional DFR1 expression and (3) the unexpected discovery of chimeric Gypsy transposable element (TE)-gene (DFR) transcripts with potential consequences to the genomic stability and post-transcriptional or epigenetic regulation of DFR. This is one of few known cases where regulatory changes and LOF mutation in an anthocyanin structural gene, rather than transcription factors, are important. Furthermore, if TEs prove to be a frequent source of mutation, the interplay between environmental stress-induced TE evolution and pollinator-mediated selection for adaptive colour variation may be an overlooked mechanism maintaining floral colour polymorphism in nature.
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Affiliation(s)
- Darren C J Wong
- Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Zemin Wang
- State Key Laboratory of Aridland Crop Science, Gansu Agricultural University, Lanzhou, China
- College of Life Science and Technology, Gansu Agricultural University, Lanzhou, China
| | - James Perkins
- Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Xin Jin
- State Key Laboratory of Aridland Crop Science, Gansu Agricultural University, Lanzhou, China
- College of Life Science and Technology, Gansu Agricultural University, Lanzhou, China
| | - Grace Emma Marsh
- Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Emma Grace John
- Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Rod Peakall
- Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
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Chapman KM, Richardson FJ, Forster CY, Middleton EJT, White TE, Burke PF, Latty T. Artificial flowers as a tool for investigating multimodal flower choice in wild insects. Ecol Evol 2023; 13:e10687. [PMID: 38020672 PMCID: PMC10659823 DOI: 10.1002/ece3.10687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 10/10/2023] [Accepted: 10/20/2023] [Indexed: 12/01/2023] Open
Abstract
Flowers come in a variety of colours, shapes, sizes and odours. Flowers also differ in the quality and quantity of nutritional reward they provide to entice potential pollinators to visit. Given this diversity, generalist flower-visiting insects face the considerable challenge of deciding which flowers to feed on and which to ignore. Working with real flowers poses logistical challenges due to correlations between flower traits, maintenance costs and uncontrolled variables. Here, we overcome this challenge by designing multimodal artificial flowers that varied in visual, olfactory and reward attributes. We used artificial flowers to investigate the impact of seven floral attributes (three visual cues, two olfactory cues and two rewarding attributes) on flower visitation and species richness. We investigated how flower attributes influenced two phases of the decision-making process: the decision to land on a flower, and the decision to feed on a flower. Artificial flowers attracted 890 individual insects representing 15 morphospecies spanning seven arthropod orders. Honeybees were the most common visitors accounting for 46% of visitors. Higher visitation rates were driven by the presence of nectar, the presence of linalool, flower shape and flower colour and was negatively impacted by the presence of citral. Species richness was driven by the presence of nectar, the presence of linalool and flower colour. For hymenopterans, the probability of landing on the artificial flowers was influenced by the presence of nectar or pollen, shape and the presence of citral and/or linalool. The probability of feeding increased when flowers contained nectar. For dipterans, the probability of landing on artificial flowers increased when the flower was yellow and contained linalool. The probability of feeding increased when flowers contained pollen, nectar and linalool. Our results demonstrate the multi-attribute nature of flower preferences and highlight the usefulness of artificial flowers as tools for studying flower visitation in wild insects.
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Affiliation(s)
- Kathryn M. Chapman
- School of Life and Environmental SciencesThe University of SydneySydneyNew South WalesAustralia
| | - Freya J. Richardson
- School of Life and Environmental SciencesThe University of SydneySydneyNew South WalesAustralia
- Sydney Institute of AgricultureThe University of SydneySydneyNew South WalesAustralia
| | - Caitlyn Y. Forster
- School of Life and Environmental SciencesThe University of SydneySydneyNew South WalesAustralia
| | - Eliza J. T. Middleton
- School of Life and Environmental SciencesThe University of SydneySydneyNew South WalesAustralia
| | - Thomas E. White
- School of Life and Environmental SciencesThe University of SydneySydneyNew South WalesAustralia
| | - Paul F. Burke
- UTS Business School and Centre for Business Intelligence and Data AnalyticsUniversity of Technology SydneySydneyNew South WalesAustralia
| | - Tanya Latty
- School of Life and Environmental SciencesThe University of SydneySydneyNew South WalesAustralia
- Sydney Institute of AgricultureThe University of SydneySydneyNew South WalesAustralia
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Howard SR, Symonds MRE. Complex preference relationships between native and non-native angiosperms and foraging insect visitors in a suburban greenspace under field and laboratory conditions. THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 2023; 110:16. [PMID: 37140757 PMCID: PMC10160202 DOI: 10.1007/s00114-023-01846-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 03/23/2023] [Accepted: 04/18/2023] [Indexed: 05/05/2023]
Abstract
The introduction and spread of non-native flora threatens native pollinators and plants. Non-native angiosperms can compete with native plants for pollinators, space, and other resources which can leave native bees without adequate nutritional or nesting resources, particularly specialist species. In the current study, we conducted flower preference experiments through field observations and controlled binary choice tests in an artificial arena to determine the impact of field vs. laboratory methods on flower preferences of native bees for native or non-native flowers within their foraging range. We conducted counts of insect pollinators foraging on the flowers of three plant species in a suburban green belt including one native (Arthropodium strictum) and two non-native (Arctotheca calendula and Taraxacum officinale) plant species. We then collected native halictid bees foraging on each of the three plant species and conducted controlled binary tests to determine their preferences for the flowers of native or non-native plant species. In the field counts, halictid bees visited the native plant significantly more than the non-native species. However, in the behavioural assays when comparing A. strictum vs. A. calendula, Lasioglossum (Chilalictus) lanarium (Family: Halictidae), bees significantly preferred the non-native species, regardless of their foraging history. When comparing A. strictum vs. T. officinale, bees only showed a preference for the non-native flower when it had been collected foraging on the flowers of that plant species immediately prior to the experiment; otherwise, they showed no flower preference. Our results highlight the influence that non-native angiosperms have on native pollinators and we discuss the complexities of the results and the possible reasons for different flower preferences under laboratory and field conditions.
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Affiliation(s)
- Scarlett R Howard
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Burwood, VIC, Australia.
- School of Biological Sciences, Monash University, Clayton, VIC, Australia.
| | - Matthew R E Symonds
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Burwood, VIC, Australia
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van der Kooi CJ, Spaethe J. Caution with colour calculations: spectral purity is a poor descriptor of flower colour visibility. ANNALS OF BOTANY 2022; 130:1-9. [PMID: 35726715 PMCID: PMC9295922 DOI: 10.1093/aob/mcac069] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 05/26/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND The colours of flowers are of key interest to plant and pollination biologists. An increasing number of studies have investigated the importance of saturation of flower colours (often called 'spectral purity' or 'chroma') for visibility to pollinators, but the conceptual, physiological and behavioural foundations for these metrics as well as the calculations used rest on slender foundations. METHODS We discuss the caveats of colour attributes that are derived from human perception, and in particular spectral purity and chroma, as variables in flower colour analysis. We re-analysed seven published datasets encompassing 774 measured reflectance spectra to test for correlations between colour contrast, spectral purity and chroma. MAIN FINDINGS AND CONCLUSIONS We identify several concerns with common calculation procedures in animal colour spaces. Studies on animal colour vision provide no ground to assume that any pollinator perceives (or responds to) saturation, chroma or spectral purity in the way humans do. A re-analysis of published datasets revealed that values for colour contrast between flowers and their background are highly correlated with measures for spectral purity and chroma, which invalidates treating these factors as independent variables as is currently commonplace. Strikingly, spectral purity and chroma - both of which are metrics for saturation and are often used synonymously - are not correlated at all. We conclude that alternative, behaviourally validated metrics for the visibility of flowers to pollinators, such as colour contrast and achromatic contrast, are better in understanding the role of flower colour in plant-pollinator signalling.
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Affiliation(s)
| | - Johannes Spaethe
- Department of Behavioral Physiology and Sociobiology, University of Würzburg, Germany
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Koethe S, Reinartz L, Heard TA, Garcia JE, Dyer AG, Lunau K. Comparative psychophysics of Western honey bee (Apis mellifera) and stingless bee (Tetragonula carbonaria) colour purity and intensity perception. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2022; 208:641-652. [PMID: 36269403 PMCID: PMC9734212 DOI: 10.1007/s00359-022-01581-y] [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: 06/02/2022] [Revised: 09/13/2022] [Accepted: 09/28/2022] [Indexed: 12/14/2022]
Abstract
Bees play a vital role as pollinators worldwide and have influenced how flower colour signals have evolved. The Western honey bee, Apis mellifera (Apini), and the Buff-tailed bumble bee, Bombus terrestris (Bombini) are well-studied model species with regard to their sensory physiology and pollination capacity, although currently far less is known about stingless bees (Meliponini) that are common in pantropical regions. We conducted comparative experiments with two highly eusocial bee species, the Western honey bee, A. mellifera, and the Australian stingless bee, Tetragonula carbonaria, to understand their colour preferences considering fine-scaled stimuli specifically designed for testing bee colour vision. We employed stimuli made of pigment powders to allow manipulation of single colour parameters including spectral purity (saturation) or colour intensity (brightness) of a blue colour (hue) for which both species have previously shown innate preferences. Both A. mellifera and T. carbonaria demonstrated a significant preference for spectrally purer colour stimuli, although this preference is more pronounced in honey bees than in stingless bees. When all other colour cues were tightly controlled, honey bees receiving absolute conditioning demonstrated a capacity to learn a high-intensity stimulus significant from chance expectation demonstrating some capacity of plasticity for this dimension of colour perception. However, honey bees failed to learn low-intensity stimuli, and T. carbonaria was insensitive to stimulus intensity as a cue. These comparative findings suggest that there may be some common roots underpinning colour perception in bee pollinators and how they interact with flowers, although species-specific differences do exist.
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Affiliation(s)
- Sebastian Koethe
- Institute of Sensory Ecology, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany
| | - Lara Reinartz
- Institute of Sensory Ecology, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany
| | | | - Jair E. Garcia
- School of Media and Communication, RMIT University, Building 5.2.36, City Campus, GPO Box 2476, Melbourne, VIC 3001 Australia
| | - Adrian G. Dyer
- School of Media and Communication, RMIT University, Building 5.2.36, City Campus, GPO Box 2476, Melbourne, VIC 3001 Australia ,Department of Physiology, Monash University, Melbourne, 3800 Australia ,Institute of Developmental Biology and Neurobiology, Johannes Gutenberg Universität, Mainz, Germany
| | - Klaus Lunau
- Institute of Sensory Ecology, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany
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Muñoz-Galicia D, Castillo-Guevara C, Lara C. Innate and learnt color preferences in the common green-eyed white butterfly ( Leptophobia aripa): experimental evidence. PeerJ 2021; 9:e12567. [PMID: 34909282 PMCID: PMC8638565 DOI: 10.7717/peerj.12567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 11/08/2021] [Indexed: 11/20/2022] Open
Abstract
Background Learning abilities help animals modify their behaviors based on experience and innate sensory biases to confront environmental unpredictability. In a food acquisition context, the ability to detect, learn, and switch is fundamental in a wide range of insect species facing the ever-changing availability of their floral rewards. Here, we used an experimental approach to address the innate color preferences and learning abilities of the common green-eyed white butterfly (Leptophobia aripa). Methods In Experiment 1, we conducted innate preference choice-tests to determine whether butterflies had a strong innate color preference and to evaluate whether color preferences differed depending on the array of colors offered. We faced naïve butterflies to artificial flowers of four colors (quadruple choice-test): yellow, pink, white, and red; their choices were assessed. In Experiment 2, we examined the ability of this butterfly species to associate colors with rewards while exploring if the spectral reflectance value of a flower color can slow or accelerate this behavioral response. Butterflies were first trained to be fed from artificial yellow flowers inserted in a feeder. These were later replaced by artificial flowers with a similar (blue) or very different (white) spectral reflectance range. Each preference test comprised a dual-choice test (yellow vs blue, yellow vs white). Results Butterflies showed an innate strong preference for red flowers. Both the number of visits and the time spent probing these flowers were much greater than the pink, white, and yellow color flowers. Butterflies learn to associate colors with sugar rewards. They then learned the newly rewarded colors as quickly and proficiently as if the previously rewarded color was similar in spectral reflectance value; the opposite occurs if the newly rewarded color is very different than the previously rewarded color. Conclusions Our findings suggest that common green-eyed white butterflies have good learning abilities. These capabilities may allow them to respond rapidly to different color stimulus.
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Affiliation(s)
- Deysi Muñoz-Galicia
- Centro de Investigación en Ciencias Biológicas, Universidad Autónoma de Tlaxcala, San Felipe, Ixtacuixtla, Tlaxcala, Mexico
| | - Citlalli Castillo-Guevara
- Centro de Investigación en Ciencias Biológicas, Universidad Autónoma de Tlaxcala, San Felipe, Ixtacuixtla, Tlaxcala, Mexico
| | - Carlos Lara
- Centro de Investigación en Ciencias Biológicas, Universidad Autónoma de Tlaxcala, San Felipe, Ixtacuixtla, Tlaxcala, Mexico
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Howard SR, Prendergast K, Symonds MRE, Shrestha M, Dyer AG. Spontaneous choices for insect-pollinated flower shapes by wild non-eusocial halictid bees. J Exp Biol 2021; 224:271069. [PMID: 34318316 DOI: 10.1242/jeb.242457] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 07/22/2021] [Indexed: 11/20/2022]
Abstract
The majority of angiosperms require animal pollination for reproduction, and insects are the dominant group of animal pollinators. Bees are considered one of the most important and abundant insect pollinators. Research into bee behaviour and foraging decisions has typically centred on managed eusocial bee species, including Apis mellifera and Bombus terrestris. Non-eusocial bees are understudied with respect to foraging strategies and decision making, such as flower preferences. Understanding whether there are fundamental foraging strategies and preferences that are features of insect groups can provide key insights into the evolution of flower-pollinator co-evolution. In the current study, Lasioglossum (Chilalictus) lanarium and Lasioglossum (Parasphecodes) sp., two native Australian generalist halictid bees, were tested for flower shape preferences between native insect-pollinated and bird-pollinated flowers. Each bee was presented with achromatic images of either insect-pollinated or bird-pollinated flowers in a circular arena. Both native bee species demonstrated a significant preference for images of insect-pollinated flowers. These preferences are similar to those found in A. mellifera, suggesting that flower shape preference may be a deep-rooted evolutionary occurrence within bees. With growing interest in the sensory capabilities of non-eusocial bees as alternative pollinators, the current study also provides a valuable framework for further behavioural testing of such species.
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Affiliation(s)
- Scarlett R Howard
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Burwood, VIC 3125, Australia
| | - Kit Prendergast
- School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Matthew R E Symonds
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Burwood, VIC 3125, Australia
| | - Mani Shrestha
- Disturbance Ecology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, 95440 Bayreuth, Germany.,Faculty of Information Technology, Monash University, Clayton, VIC 3800, Australia
| | - Adrian G Dyer
- School of Media and Communication, RMIT University, Melbourne, VIC 3000, Australia.,Department of Physiology, Monash University, Clayton, VIC 3800, Australia
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Howard SR. Wild non-eusocial bees learn a colour discrimination task in response to simulated predation events. Naturwissenschaften 2021; 108:28. [PMID: 34152477 DOI: 10.1007/s00114-021-01739-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 04/06/2021] [Accepted: 05/31/2021] [Indexed: 02/08/2023]
Abstract
Despite representing the majority of bee species, non-eusocial bees (e.g. solitary, subsocial, semisocial, and quasisocial species) are comparatively understudied in learning, memory, and cognitive-like behaviour compared to eusocial bees, such as honeybees and bumblebees. Ecologically relevant colour discrimination tasks are well-studied in eusocial bees, and research has shown that a few non-eusocial bee species are also capable of colour learning and long-term memory retention. Australia hosts over 2000 native bee species, most of which are non-eusocial, yet evidence of cognitive-like behaviour and learning abilities under controlled testing conditions is lacking. In the current study, I examine the learning ability of a non-eusocial Australian bee, Lasioglossum (Chilalictus) lanarium, using aversive differential conditioning during a colour discrimination task. L. lanarium learnt to discriminate between salient blue- and yellow-coloured stimuli following training with simulated predation events. This study acts as a bridge between cognitive studies on eusocial and non-social bees and introduces a framework for testing non-eusocial wild bees on elemental visual learning tasks using aversive conditioning. Non-eusocial bee species are far more numerous than eusocial species and contribute to agriculture, economics, and ecosystem services in Australia and across the globe. Thus, it is important to study their capacity to learn flower traits allowing for successful foraging and pollination events, thereby permitting us a better understanding of their role in plant-pollinator interactions.
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Affiliation(s)
- Scarlett R Howard
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Burwood, VIC, Australia.
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