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Fan XQ, Trunschke J, Ren ZX, Wang H, Pyke GH, van der Kooi CJ, Lunau K. Why are the inner and outer sides of many flower petals differently coloured? PLANT BIOLOGY (STUTTGART, GERMANY) 2024; 26:665-674. [PMID: 38935692 DOI: 10.1111/plb.13680] [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: 02/02/2024] [Accepted: 05/30/2024] [Indexed: 06/29/2024]
Abstract
The flower perianth has various, non-mutually exclusive functions, such as visual signalling to pollinators and protecting the reproductive organs from the elements and from florivores, but how different perianth structures and their different sides play a role in these functions is unclear. Intriguingly, in many species there is a clear colour difference between the different sides of the perianth, with colour patterns or pigmentation present on only one side. Any adaptive benefit from such colour asymmetry is unclear, as is how the asymmetry evolved. In this viewpoint paper, we address the phenomenon of flowers with differently coloured inner and outer perianth sides, focusing on petals of erect flowers. Guided by existing literature and our own observations, we delineate three non-mutually exclusive evolutionary hypotheses that may explain the factors underlying differently coloured perianth sides. The pollen-protection hypothesis predicts that the outer side of petals contributes to protect pollen against UV radiation, especially during the bud stage. The herbivore-avoidance hypothesis predicts that the outer side of petals reduces the flower's visibility to herbivores. The signalling-to-pollinators hypothesis predicts that flower colours evolve to increase conspicuousness to pollinators. The pollen-protection hypothesis, the herbivore-avoidance hypothesis, and the signalling-to-pollinators hypothesis generate largely but not entirely overlapping predictions about the colour of the inner and outer side of the petals. Field and laboratory research is necessary to disentangle the main drivers and adaptive significance of inner-outer petal side colour asymmetry.
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Affiliation(s)
- X-Q Fan
- CAS Key Laboratory of Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - J Trunschke
- CAS Key Laboratory of Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Z-X Ren
- CAS Key Laboratory of Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - H Wang
- CAS Key Laboratory of Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - G H Pyke
- CAS Key Laboratory of Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- School of Natural Sciences, Macquarie University, Ryde, NSW, Australia
| | - C J van der Kooi
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | - K Lunau
- CAS Key Laboratory of Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- Faculty of Mathematics and Natural Sciences, Institute of Sensory Ecology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
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2
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Lunau K, Dyer AG. The modelling of flower colour: spectral purity or colour contrast as biologically relevant descriptors of flower colour signals for bees depending upon the perceptual task. PLANT BIOLOGY (STUTTGART, GERMANY) 2024. [PMID: 38958933 DOI: 10.1111/plb.13682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 05/07/2024] [Indexed: 07/04/2024]
Abstract
Flower colour is an important mediator of plant-pollinator interactions. While the reflectance of light from the flower surface and background are governed by physical properties, the perceptual interpretation of such information is generated by complex multilayered visual processing. Should quantitative modelling of flower signals strive for repeatable consistency enabled by parameter simplification, or should modelling reflect the dynamic way in which bees are known to process signals? We discuss why colour is an interpretation of spectral information by the brain of an animal. Different species, or individuals within a species, may respond differently to colour signals depending on sensory apparatus and/or individual experience. Humans and bees have different spectral ranges, but colour theory is strongly rooted in human colour perception and many principles of colour vision appear to be common. We discuss bee colour perception based on physiological, neuroanatomical and behavioural evidence to provide a pathway for modelling flower colours. We examine whether flower petals and floral guides as viewed against spectrally different backgrounds should be considered as a simple colour contrast problem or require a more dynamic consideration of how bees make perceptual decisions. We discuss that plants such as deceptive orchids may present signals to exploit bee perception, whilst many plants do provide honest signalling where perceived saturation indicates the probability of collecting nutritional rewards towards the centre of a flower that then facilitates effective pollination.
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Affiliation(s)
- K Lunau
- Faculty of Mathematics and Natural Sciences, Institute of Sensory Ecology, Heinrich-Heine University, Düsseldorf, Germany
| | - A G Dyer
- Department of Physiology, Monash University, Clayton, Australia
- Institut für Entwicklungsbiologie, und Neurobiologie, Johannes Gutenberg Universität, Mainz, Germany
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3
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Lunau K, De Camargo MGG, Brito VLG. Pollen, anther, stamen, and androecium mimicry. PLANT BIOLOGY (STUTTGART, GERMANY) 2024; 26:349-368. [PMID: 38407440 DOI: 10.1111/plb.13628] [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: 12/21/2023] [Accepted: 01/23/2024] [Indexed: 02/27/2024]
Abstract
Floral colours represent a highly diverse communication signal mainly involved in flower visitors' attraction and guidance, but also flower discrimination, filtering non-pollinators and discouraging floral antagonists. The divergent visual systems and colour preferences of flower visitors, as well as the necessity of cues for flower detection and discrimination, foster the diversity of floral colours and colour patterns. Despite the bewildering diversity of floral colour patterns, a recurrent component is a yellow UV-absorbing floral centre, and it is still not clear why this pattern is so frequent in angiosperms. The pollen, anther, stamen, and androecium mimicry (PASAM) hypothesis suggests that the system composed of the flowers possessing such yellow UV-absorbing floral reproductive structures, the flowers displaying central yellow UV-absorbing structures as floral guides, and the pollen-collecting, as well as pollen-eating, flower visitors responding to such signals constitute the world's most speciose mimicry system. In this review, we call the attention of researchers to some hypothetical PASAM systems around the globe, presenting some fascinating examples that illustrate their huge diversity. We will also present new and published data on pollen-eating and pollen-collecting pollinators' responses to PASAM structures supporting the PASAM hypothesis and will discuss how widespread these systems are around the globe. Ultimately, our goal is to promote the idea that PASAM is a plausible first approach to understanding floral colour patterns in angiosperms.
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Affiliation(s)
- K Lunau
- Faculty of Mathematics and Natural Sciences, Institute of Sensory Ecology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - M G G De Camargo
- Phenology Lab, Department of Biodiversity, Biosciences Institute, UNESP - São Paulo State University, Rio Claro, São Paulo, Brazil
| | - V L G Brito
- Instituto de Biologia, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais, Brazil
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4
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Balandra A, Doll Y, Hirose S, Kajiwara T, Kashino Z, Inami M, Koshimizu S, Fukaki H, Watahiki MK. P-MIRU, a Polarized Multispectral Imaging System, Reveals Reflection Information on the Biological Surface. PLANT & CELL PHYSIOLOGY 2023; 64:1311-1322. [PMID: 37217180 DOI: 10.1093/pcp/pcad045] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 04/12/2023] [Accepted: 05/20/2023] [Indexed: 05/24/2023]
Abstract
Reflection light forms the core of our visual perception of the world. We can obtain vast information by examining reflection light from biological surfaces, including pigment composition and distribution, tissue structure and surface microstructure. However, because of the limitations in our visual system, the complete information in reflection light, which we term 'reflectome', cannot be fully exploited. For example, we may miss reflection light information outside our visible wavelengths. In addition, unlike insects, we have virtually no sensitivity to light polarization. We can detect non-chromatic information lurking in reflection light only with appropriate devices. Although previous studies have designed and developed systems for specialized uses supporting our visual systems, we still do not have a versatile, rapid, convenient and affordable system for analyzing broad aspects of reflection from biological surfaces. To overcome this situation, we developed P-MIRU, a novel multispectral and polarization imaging system for reflecting light from biological surfaces. The hardware and software of P-MIRU are open source and customizable and thus can be applied for virtually any research on biological surfaces. Furthermore, P-MIRU is a user-friendly system for biologists with no specialized programming or engineering knowledge. P-MIRU successfully visualized multispectral reflection in visible/non-visible wavelengths and simultaneously detected various surface phenotypes of spectral polarization. The P-MIRU system extends our visual ability and unveils information on biological surfaces.
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Affiliation(s)
| | - Yuki Doll
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-0033 Japan
| | - Shogo Hirose
- Faculty of Agriculture, Meijo University, Shiogamaguchi 1-501, Tempaku-ku, Nagoya, 468-0073 Japan
| | - Tomoaki Kajiwara
- Graduate School of Biostudies, Kyoto University, Yoshida-Konoecho, Sakyo-ku, Kyoto, 606-8502 Japan
| | - Zendai Kashino
- Research Center for Advanced Science and Technology, The University of Tokyo, Komaba 4-6-1, Meguro-ku, Tokyo, 153-8904 Japan
| | - Masahiko Inami
- Research Center for Advanced Science and Technology, The University of Tokyo, Komaba 4-6-1, Meguro-ku, Tokyo, 153-8904 Japan
| | - Shizuka Koshimizu
- School of Agriculture, Meiji University, Higashimita 1-1-1, Tama-ku, Kawasaki, 214-8571 Japan
- Research Center for Advanced Science and Technology, The University of Tokyo, Komaba 4-6-1, Meguro-ku, Tokyo, 153-8904 Japan
| | - Hidehiro Fukaki
- Department of Biology, Graduate School of Science, Kobe University, Rokkodaicho 1-1, Nada-ku, Kobe, 657-8501 Japan
| | - Masaaki K Watahiki
- Faculty of Science and Graduate School of Life Science, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo, 060-0810 Japan
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Scaccabarozzi D, Lunau K, Guzzetti L, Cozzolino S, Dyer AG, Tommasi N, Biella P, Galimberti A, Labra M, Bruni I, Pattarini G, Brundrett M, Gagliano M. Mimicking orchids lure bees from afar with exaggerated ultraviolet signals. Ecol Evol 2023; 13:e9759. [PMID: 36726874 PMCID: PMC9884568 DOI: 10.1002/ece3.9759] [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: 08/27/2022] [Revised: 12/22/2022] [Accepted: 01/04/2023] [Indexed: 02/03/2023] Open
Abstract
Flowers have many traits to appeal to pollinators, including ultraviolet (UV) absorbing markings, which are well-known for attracting bees at close proximity (e.g., <1 m). While striking UV signals have been thought to attract pollinators also from far away, if these signals impact the plant pollinia removal over distance remains unknown. Here, we report the case of the Australian orchid Diuris brumalis, a nonrewarding species, pollinated by bees via mimicry of the rewarding pea plant Daviesia decurrens. When distant from the pea plant, Diuris was hypothesized to enhance pollinator attraction by exaggeratedly mimicking the floral ultraviolet (UV) reflecting patterns of its model. By experimentally modulating floral UV reflectance with a UV screening solution, we quantified the orchid pollinia removal at a variable distance from the model pea plants. We demonstrate that the deceptive orchid Diuris attracts bee pollinators by emphasizing the visual stimuli, which mimic the floral UV signaling of the rewarding model Daviesia. Moreover, the exaggerated UV reflectance of Diuris flowers impacted pollinators' visitation at an optimal distance from Da. decurrens, and the effect decreased when orchids were too close or too far away from the model. Our findings support the hypothesis that salient UV flower signaling plays a functional role in visual floral mimicry, likely exploiting perceptual gaps in bee neural coding, and mediates the plant pollinia removal at much greater spatial scales than previously expected. The ruse works most effectively at an optimal distance of several meters revealing the importance of salient visual stimuli when mimicry is imperfect.
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Affiliation(s)
- Daniela Scaccabarozzi
- School of Pharmaceutical Science and TechnologyTianjin UniversityTianjinChina
- School of Molecular and Life SciencesCurtin UniversityBentleyWestern AustraliaAustralia
| | - Klaus Lunau
- Institute of Sensory EcologyHeinrich‐Heine University DüsseldorfDüsseldorfGermany
| | - Lorenzo Guzzetti
- ZooPlantLab, Dipartimento di Biotecnologie e BioscienzeUniversity of Milano – BicoccaMilanItaly
| | | | - Adrian G. Dyer
- Bio‐Inspired Digital Sensing Lab, School of Media and CommunicationRMIT UniversityMelbourneVictoriaAustralia
- Department of Physiology and Neuroscience Program, Biomedicine Discovery InstituteMonash UniversityClaytonVictoriaAustralia
| | - Nicola Tommasi
- ZooPlantLab, Dipartimento di Biotecnologie e BioscienzeUniversity of Milano – BicoccaMilanItaly
| | - Paolo Biella
- ZooPlantLab, Dipartimento di Biotecnologie e BioscienzeUniversity of Milano – BicoccaMilanItaly
| | - Andrea Galimberti
- ZooPlantLab, Dipartimento di Biotecnologie e BioscienzeUniversity of Milano – BicoccaMilanItaly
| | - Massimo Labra
- ZooPlantLab, Dipartimento di Biotecnologie e BioscienzeUniversity of Milano – BicoccaMilanItaly
| | - Ilaria Bruni
- ZooPlantLab, Dipartimento di Biotecnologie e BioscienzeUniversity of Milano – BicoccaMilanItaly
| | - Giorgio Pattarini
- Department of Mathematics and PhysicsUniversity of StavangerStavangerNorway
| | - Mark Brundrett
- School of Biological SciencesUniversity of Western AustraliaPerthWestern AustraliaAustralia
| | - Monica Gagliano
- Biological Intelligence (BI) Lab, Faculty of Sciences & EngineeringSouthern Cross UniversityLismoreNew South WalesAustralia
- Sydney Environment Institute (SEI)The University of SydneyCamperdownNew South WalesAustralia
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Eco-Evo-Devo of petal pigmentation patterning. Essays Biochem 2022; 66:753-768. [PMID: 36205404 DOI: 10.1042/ebc20220051] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 09/09/2022] [Accepted: 09/13/2022] [Indexed: 12/13/2022]
Abstract
Colourful spots, stripes and rings decorate the corolla of most flowering plants and fulfil important biotic and abiotic functions. Spatial differences in the pigmentation of epidermal cells can create these patterns. The last few years have yielded new data that have started to illuminate the mechanisms controlling the function, formation and evolution of petal patterns. These advances have broad impacts beyond the immediate field as pigmentation patterns are wonderful systems to explore multiscale biological problems: from understanding how cells make decisions at the microscale to examining the roots of biodiversity at the macroscale. These new results also reveal there is more to petal patterning than meets the eye, opening up a brand new area of investigation. In this mini-review, we summarise our current knowledge on the Eco-Evo-Devo of petal pigmentation patterns and discuss some of the most exciting yet unanswered questions that represent avenues for future research.
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Basso-Alves JP, da Silva RF, Coimbra G, Leitão SG, de Rezende CM, Bizzo HR, Freitas L, Paulino JV, Mansano VDF. Heteromorphic stamens are differentially attractive in Swartzia (Fabaceae). AOB PLANTS 2022; 14:plac041. [PMID: 36267642 PMCID: PMC9575666 DOI: 10.1093/aobpla/plac041] [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: 03/17/2022] [Accepted: 09/08/2022] [Indexed: 06/16/2023]
Abstract
The division of labour hypothesis between stamens has explained the evolution of divergent functions between dimorphic stamens in the same flower. However, little is known about whether the distinct type of stamens differs in attractiveness to pollinators. Therefore, we investigate whether the two types of stamens commonly found in Swartzia have different visual and olfactory attractants. We performed observations of anthesis dynamics, registration and collection of floral visitors, measurements of reflectance of floral parts and chemical analysis of the volatile organic compounds of the floral parts of two species, S. flaemingii and S. simplex. Both species have two distinct sets of stamens: one with smaller and abundant stamens in the centre of the flower and the other with fewer but larger abaxial stamens. The sets differ in UV reflectance (only S. simplex) and exhibit a distinct chromatic contrast. Concerning olfactory attractiveness, aliphatic compounds make up most of the odour of the two species, both whole flowers and most of their floral organs. On the other hand, only S. simplex presented apocarotenoids (as ionones) and benzenoids. Furthermore, there are differences in the proportion of volatiles emitted by the stamen in both cases, as the high proportion of sesquiterpenes among the smaller stamens compared to the larger ones. In conclusion, the two types of stamens found in S. flaemingii and S. simplex show a distinct attractiveness. In addition, our data have demonstrated diverse ways of differential attractiveness both between distinct stamens set per flower and between the two species from the same pollen flowers genus.
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Affiliation(s)
| | - Rafael Ferreira da Silva
- Departamento de Química Orgânica/GQO, Instituto de Química, Universidade Federal Fluminense (UFF), Niterói, RJ 24020141, Brazil
| | - Gabriel Coimbra
- Programa de Pós-Graduação em Botânica, Escola Nacional de Botânica Tropical, Jardim Botânico do Rio de Janeiro, Rio de Janeiro, RJ 22460-036, Brazil
- Instituto de Pesquisas Jardim Botânico do Rio de Janeiro, DIPEQ-JBRJ, Rio de Janeiro, RJ 22460-030, Brazil
| | - Suzana Guimarães Leitão
- Departamento de Produtos Naturais e Alimentos, Faculdade de Farmácia, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21941-902, Brazil
| | - Claudia Moraes de Rezende
- Instituto de Química, Centro de Tecnologia, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 22945970, Brazil
| | | | - Leandro Freitas
- Programa de Pós-Graduação em Botânica, Escola Nacional de Botânica Tropical, Jardim Botânico do Rio de Janeiro, Rio de Janeiro, RJ 22460-036, Brazil
- Instituto de Pesquisas Jardim Botânico do Rio de Janeiro, DIPEQ-JBRJ, Rio de Janeiro, RJ 22460-030, Brazil
| | - Juliana Villela Paulino
- Programa de Pós-Graduação em Botânica, Escola Nacional de Botânica Tropical, Jardim Botânico do Rio de Janeiro, Rio de Janeiro, RJ 22460-036, Brazil
- Departamento de Produtos Naturais e Alimentos, Faculdade de Farmácia, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ 21941-902, Brazil
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León‐Osper M, Narbona E. Unravelling the mystery of red flowers in the Mediterranean Basin: How to be conspicuous in a place dominated by hymenopteran pollinators. Funct Ecol 2022. [DOI: 10.1111/1365-2435.14166] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Melissa León‐Osper
- Departamento de Biología Molecular e Ingeniería Bioquímica, Universidad Pablo de Olavide Sevilla España
| | - Eduardo Narbona
- Departamento de Biología Molecular e Ingeniería Bioquímica, Universidad Pablo de Olavide Sevilla España
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9
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Van de Beeck L, Plowright CMS. A new touchscreen for behavioural research on bees. Ethology 2022. [DOI: 10.1111/eth.13269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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10
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Garcia JE, Dyer AG. False colour photography reveals the complexity of flower signalling. A Commentary on: 'A bee's eye view of remarkable floral colour patterns in the Southwest Australian biodiversity hotspot revealed by false colour photography'. ANNALS OF BOTANY 2021; 128:i-ii. [PMID: 34212974 PMCID: PMC8577202 DOI: 10.1093/aob/mcab076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
This article comments on: Klaus Lunau, Daniela Scaccabarozzi, Larissa Willing and Kingsley Dixon, A bee’s eye view of remarkable floral colour patterns in the Southwest Australian biodiversity hotspot revealed by false colour photography’, Annals of Botany, Volume 128, Issue 7, 2 December 2021, Pages 821–824 https://doi.org/10.1093/aob/mcab088
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Affiliation(s)
- Jair E Garcia
- School of Media and Communication, RMIT University, Melbourne 3001, Australia
| | - Adrian G Dyer
- School of Media and Communication, RMIT University, Melbourne 3001, Australia
- Department of Physiology, Monash University, Melbourne 3800, Australia
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Narbona E, del Valle JC, Arista M, Buide ML, Ortiz PL. Major Flower Pigments Originate Different Colour Signals to Pollinators. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.743850] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Flower colour is mainly due to the presence and type of pigments. Pollinator preferences impose selection on flower colour that ultimately acts on flower pigments. Knowing how pollinators perceive flowers with different pigments becomes crucial for a comprehensive understanding of plant-pollinator communication and flower colour evolution. Based on colour space models, we studied whether main groups of pollinators, specifically hymenopterans, dipterans, lepidopterans and birds, differentially perceive flower colours generated by major pigment groups. We obtain reflectance data and conspicuousness to pollinators of flowers containing one of the pigment groups more frequent in flowers: chlorophylls, carotenoids and flavonoids. Flavonoids were subsequently classified in UV-absorbing flavonoids, aurones-chalcones and the anthocyanins cyanidin, pelargonidin, delphinidin, and malvidin derivatives. We found that flower colour loci of chlorophylls, carotenoids, UV-absorbing flavonoids, aurones-chalcones, and anthocyanins occupied different regions of the colour space models of these pollinators. The four groups of anthocyanins produced a unique cluster of colour loci. Interestingly, differences in colour conspicuousness among the pigment groups were almost similar in the bee, fly, butterfly, and bird visual space models. Aurones-chalcones showed the highest chromatic contrast values, carotenoids displayed intermediate values, and chlorophylls, UV-absorbing flavonoids and anthocyanins presented the lowest values. In the visual model of bees, flowers with UV-absorbing flavonoids (i.e., white flowers) generated the highest achromatic contrasts. Ours findings suggest that in spite of the almost omnipresence of floral anthocyanins in angiosperms, carotenoids and aurones-chalcones generates higher colour conspicuousness for main functional groups of pollinators.
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