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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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Honkanen A, Hensgen R, Kannan K, Adden A, Warrant E, Wcislo W, Heinze S. Parallel motion vision pathways in the brain of a tropical bee. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2023:10.1007/s00359-023-01625-x. [PMID: 37017717 DOI: 10.1007/s00359-023-01625-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 03/01/2023] [Accepted: 03/09/2023] [Indexed: 04/06/2023]
Abstract
Spatial orientation is a prerequisite for most behaviors. In insects, the underlying neural computations take place in the central complex (CX), the brain's navigational center. In this region different streams of sensory information converge to enable context-dependent navigational decisions. Accordingly, a variety of CX input neurons deliver information about different navigation-relevant cues. In bees, direction encoding polarized light signals converge with translational optic flow signals that are suited to encode the flight speed of the animals. The continuous integration of speed and directions in the CX can be used to generate a vector memory of the bee's current position in space in relation to its nest, i.e., perform path integration. This process depends on specific, complex features of the optic flow encoding CX input neurons, but it is unknown how this information is derived from the visual periphery. Here, we thus aimed at gaining insight into how simple motion signals are reshaped upstream of the speed encoding CX input neurons to generate their complex features. Using electrophysiology and anatomical analyses of the halictic bees Megalopta genalis and Megalopta centralis, we identified a wide range of motion-sensitive neurons connecting the optic lobes with the central brain. While most neurons formed pathways with characteristics incompatible with CX speed neurons, we showed that one group of lobula projection neurons possess some physiological and anatomical features required to generate the visual responses of CX optic-flow encoding neurons. However, as these neurons cannot explain all features of CX speed cells, local interneurons of the central brain or alternative input cells from the optic lobe are additionally required to construct inputs with sufficient complexity to deliver speed signals suited for path integration in bees.
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Affiliation(s)
- Anna Honkanen
- Lund Vision Group, Department of Biology, Lund University, Lund, Sweden
| | - Ronja Hensgen
- Lund Vision Group, Department of Biology, Lund University, Lund, Sweden
| | - Kavitha Kannan
- Lund Vision Group, Department of Biology, Lund University, Lund, Sweden
| | - Andrea Adden
- Lund Vision Group, Department of Biology, Lund University, Lund, Sweden
- Neural Circuits and Evolution Lab, The Francis Crick Institute, London, UK
| | - Eric Warrant
- Lund Vision Group, Department of Biology, Lund University, Lund, Sweden
| | - William Wcislo
- Smithsonian Tropical Research Institute, Panama City, República de Panamá
| | - Stanley Heinze
- Lund Vision Group, Department of Biology, Lund University, Lund, Sweden.
- NanoLund, Lund University, Lund, Sweden.
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Mission impossible: honey bees adjust time allocation when facing an unsolvable task. Anim Behav 2021. [DOI: 10.1016/j.anbehav.2021.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Dyer AG, Greentree AD, Garcia JE, Dyer EL, Howard SR, Barth FG. Einstein, von Frisch and the honeybee: a historical letter comes to light. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2021; 207:449-456. [PMID: 33970340 PMCID: PMC8222030 DOI: 10.1007/s00359-021-01490-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 04/27/2021] [Accepted: 04/28/2021] [Indexed: 12/04/2022]
Abstract
The work of the Nobel Laureate Karl von Frisch, the founder of this journal, was seminal in many ways. He established the honeybee as a key animal model for experimental behavioural studies on sensory perception, learning and memory, and first correctly interpreted its famous dance communication. Here, we report on a previously unknown letter by the Physicist and Nobel Laureate Albert Einstein that was written in October 1949. It briefly addresses the work of von Frisch and also queries how understanding animal perception and navigation may lead to innovations in physics. We discuss records proving that Einstein and von Frisch met in April 1949 when von Frisch visited the USA to present a lecture on bees at Princeton University. In the historical context of Einstein’s theories and thought experiments, we discuss some more recent discoveries of animal sensory capabilities alien to us humans and potentially valuable for bio-inspired design improvements. We also address the orientation of animals like migratory birds mentioned by Einstein 70 years ago, which pushes the boundaries of our understanding nature, both its biology and physics.
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Affiliation(s)
- Adrian G Dyer
- School of Media and Communication, RMIT University, Melbourne, VIC, 3001, Australia
- Department of Physiology, Monash University, Clayton, VIC, 3800, Australia
| | - Andrew D Greentree
- ARC Centre of Excellence for Nanoscale BioPhotonics, School of Science, RMIT University, Melbourne, VIC, 3001, Australia
| | - Jair E Garcia
- School of Media and Communication, RMIT University, Melbourne, VIC, 3001, Australia
| | - Elinya L Dyer
- Department of Computer Science and Software Engineering, Swinburne University of Technology, Hawthorn, VIC, 3122, Australia
| | - Scarlett R Howard
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Burwood, VIC, 3217, Australia
| | - Friedrich G Barth
- Department of Neurosciences and Developmental Biology, Faculty of Life Sciences, University of Vienna, Althanstr.14, 1090, Vienna, Austria.
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Hannah L, Dyer AG, Garcia JE, Dorin A, Burd M. Psychophysics of the hoverfly: categorical or continuous color discrimination? Curr Zool 2019; 65:483-492. [PMID: 31413720 PMCID: PMC6688577 DOI: 10.1093/cz/zoz008] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 02/26/2019] [Indexed: 12/12/2022] Open
Abstract
There is increasing interest in flies as potentially important pollinators. Flies are known to have a complex visual system, including 4 spectral classes of photoreceptors that contribute to the perception of color. Our current understanding of how color signals are perceived by flies is based on data for the blowfly Lucilia sp., which after being conditioned to rewarded monochromatic light stimuli, showed evidence of a categorical color visual system. The resulting opponent fly color space has 4 distinct categories, and has been used to interpret how some fly pollinators may perceive flower colors. However, formal proof that flower flies (Syrphidae) only use a simple, categorical color process remains outstanding. In free-flying experiments, we tested the hoverfly Eristalis tenax, a Batesian mimic of the honeybee, that receives its nutrition by visiting flowers. Using a range of broadband similar–dissimilar color stimuli previously used to test color perception in pollinating hymenopteran species, we evaluated if there are steep changes in behavioral choices with continuously increasing color differences as might be expected by categorical color processing. Our data revealed that color choices by the hoverfly are mediated by a continuous monotonic function. Thus, these flies did not use a categorical processing, but showed evidence of a color discrimination function similar to that observed in several bee species. We therefore empirically provide data for the minimum color distance that can be discriminated by hoverflies in fly color space, enabling an improved understanding of plant–pollinator interactions with a non-model insect species.
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Affiliation(s)
- Lea Hannah
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia.,Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales 2753, Australia
| | - Adrian G Dyer
- School of Media and Communication, RMIT University, Melbourne, Victoria 3001, Australia.,Department of Physiology, Monash University, Clayton, Victoria 3800, Australia
| | - Jair E Garcia
- School of Media and Communication, RMIT University, Melbourne, Victoria 3001, Australia
| | - Alan Dorin
- Faculty of Information Technology, Monash University, Clayton, Victoria 3800, Australia
| | - Martin Burd
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
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Ng L, Garcia JE, Dyer AG. Why colour is complex: Evidence that bees perceive neither brightness nor green contrast in colour signal processing. Facets (Ott) 2018. [DOI: 10.1139/facets-2017-0116] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Honey bees ( Apis mellifera Linnaeus, 1758) potentially rely on a variety of visual cues when searching for flowers in the environment. Both chromatic and achromatic (brightness) components of flower signals have typically been considered simultaneously to understand how flower colours have evolved. However, it is unclear whether honey bees actually use brightness information in their colour perception. We investigated whether free-flying honey bees can process brightness cues in achromatic stimuli when presented at a large visual angle of 28° to ensure colour processing. We found that green contrast (modulation of the green receptor against the background) and brightness contrast (modulation of all three receptors against the background) did not have a significant effect on the proportion of correct choices made by bees, indicating that they did not appear to use brightness cues in a colour processing context. Our findings also reveal that, even at a small visual angle, honeybees do not reliably process single targets solely based on achromatic information, at least considering values up to 60% modulation of brightness. We discuss these findings in relation to proposed models of bee colour processing. Therefore, caution should be taken when interpreting elemental components of complex flower colours as perceived by different animals.
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Affiliation(s)
- Leslie Ng
- Bio-Inspired Digital Sensing (BIDS) Lab, School of Media and Communication, RMIT University, Melbourne, VIC 3001, Australia
- School of Biosciences, University of Melbourne, Melbourne, Parkville, VIC 3010, Australia
| | - Jair E. Garcia
- Bio-Inspired Digital Sensing (BIDS) Lab, School of Media and Communication, RMIT University, Melbourne, VIC 3001, Australia
| | - Adrian G. Dyer
- Bio-Inspired Digital Sensing (BIDS) Lab, School of Media and Communication, RMIT University, Melbourne, VIC 3001, Australia
- Department of Physiology, Monash University, Melbourne, Clayton, VIC 3800, Australia
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Honkanen A, Saari P, Takalo J, Heimonen K, Weckström M. The role of ocelli in cockroach optomotor performance. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2017; 204:231-243. [PMID: 29192330 PMCID: PMC5799336 DOI: 10.1007/s00359-017-1235-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 11/17/2017] [Accepted: 11/23/2017] [Indexed: 11/28/2022]
Abstract
Insect ocelli are relatively simple eyes that have been assigned various functions not related to pictorial vision. In some species they function as sensors of ambient light intensity, from which information is relayed to various parts of the nervous system, e.g., for the control of circadian rhythms. In this work we have investigated the possibility that the ocellar light stimulation changes the properties of the optomotor performance of the cockroach Periplaneta americana. We used a virtual reality environment where a panoramic moving image is presented to the cockroach while its movements are recorded with a trackball. Previously we have shown that the optomotor reaction of the cockroach persists down to the intensity of moonless night sky, equivalent to less than 0.1 photons/s being absorbed by each compound eye photoreceptor. By occluding the compound eyes, the ocelli, or both, we show that the ocellar stimulation can change the intensity dependence of the optomotor reaction, indicating involvement of the ocellar visual system in the information processing of movement. We also measured the cuticular transmission, which, although relatively large, is unlikely to contribute profoundly to ocellar function, but may be significant in determining the mean activity level of completely blinded cockroaches.
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Affiliation(s)
- Anna Honkanen
- Nano and Molecular Systems Research Unit, University of Oulu, P.O. Box 3000, 90014, Oulu, Finland. .,Vision Group, Department of Biology, Lund University, 223 62, Lund, Sweden.
| | - Paulus Saari
- Nano and Molecular Systems Research Unit, University of Oulu, P.O. Box 3000, 90014, Oulu, Finland
| | - Jouni Takalo
- Nano and Molecular Systems Research Unit, University of Oulu, P.O. Box 3000, 90014, Oulu, Finland.,Centre for Cognition in Small Brains, Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | - Kyösti Heimonen
- Nano and Molecular Systems Research Unit, University of Oulu, P.O. Box 3000, 90014, Oulu, Finland
| | - Matti Weckström
- Nano and Molecular Systems Research Unit, University of Oulu, P.O. Box 3000, 90014, Oulu, Finland
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Garcia JE, Spaethe J, Dyer AG. The path to colour discrimination is S-shaped: behaviour determines the interpretation of colour models. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2017; 203:983-997. [DOI: 10.1007/s00359-017-1208-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 08/09/2017] [Accepted: 08/10/2017] [Indexed: 10/18/2022]
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