| 1. |
- Balkenius, Anna, et al.
(författare)
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A model of selecion between stimulus and place strategy in a hawkmoth
- 2004
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Ingår i: Adaptive Behavior. - : SAGE Publications. - 1741-2633 .- 1059-7123. ; 12:1, s. 21-35
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Tidskriftsartikel (refereegranskat)abstract
- In behavioral experiments, the hawkmoth Deilephila elpenor can learn both the color and the position of artificial flowers. When very similar colors are used, moths select the correct color during the first test on a given day, thus using a stimulus strategy, but after repeated rewards, they switch to a place strategy and choose the flower in the position where they received the reward. When dissimilar colors are used, the moths continue to select flowers based on color and ignore position. We show how a computational model can reproduce the behavior in the experimental situation. The aim of the model is to investigate which learning and behavior selection strategies are necessary to reproduce the behavior observed in the experiment. The model is based on behavioral data and the sensitivities of the moth photoreceptors. The model consists of a number of interacting behavior systems that are triggered by specific stimuli and control specific behaviors. The ability of the moth to learn the colors of different flowers and the adaptive processes involved in the choice between stimulus-approach and place-approach strategies are reproduced very accurately by the model. The model has implications both for further studies of the ecology of the animal and for robotic systems.
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| 2. |
- Balkenius, Anna, et al.
(författare)
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Colour constancy in diurnal and nocturnal hawkmoths
- 2004
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 1477-9145 .- 0022-0949. ; 207:19, s. 3307-3316
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Tidskriftsartikel (refereegranskat)abstract
- Diurnal and nocturnal hawkmoths have been shown to use colour vision for flower discrimination. Here, we present evidence that the nocturnal hawkmoth Deilephila elpenor and the diurnal hawkmoth Macroglossum stellatarum also have colour constancy. Colour constancy was shown in D. elpenor in two multiple-choice experiments with five different bluish colour patches under white and blue illumination and with five yellowish colour patches under white, blue and yellow illumination. The mechanism underlying colour constancy in both species was investigated in two dual-choice experiments. The choice behaviour is consistent with the use of the von Kries coefficient law. Although the moths have colour constancy, they react to the colour of the illumination. They make fewer choices when tested under the changed illumination, where they never receive a reward, compared with the training illumination. Even if colour constancy can be explained by a von Kries adaptation mechanism, the fact that the animals discriminate between different illuminations indicates that some additional process must be involved.
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| 3. |
- Balkenius, Anna, et al.
(författare)
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Colour preferences influences odour learning in the hawkmoth, Macroglossum stellatarum
- 2006
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Ingår i: Naturwissenschaften. - : Springer Science and Business Media LLC. - 1432-1904 .- 0028-1042. ; 93:5, s. 255-258
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Tidskriftsartikel (refereegranskat)abstract
- The hummingbird hawkmoth, Macroglossum stellatarum, learns colour fast and reliably. It has earlier been shown to spontaneously feed from odourless artificial flowers. Now, we have studied odour learning. The moths were trained to discriminate feeders of the same colour but marked with different odours. They did not learn to discriminate two natural flower odours when they were presented with the innately preferred colour blue, but they did learn this discrimination combined with yellow or green colours that are less attractive to the moth. The yellow colour could be trained to become as attractive as the innately preferred blue colour and the blue colour could be trained to become less attractive. This is the first proof of odour learning in a diurnal moth. The results show that M. stellatarum can use more than one modality in their foraging behaviour and that the system is plastic. By manipulating the preferences for the different colours, their influence on odour learning could be changed.
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| 4. |
- Balkenius, Anna, et al.
(författare)
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How do Hawkmoths Learn Multi-Modal Stimuli? A Comparison of Three Models
- 2008
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Ingår i: Adaptive Behavior. - : SAGE Publications. - 1741-2633 .- 1059-7123. ; 16:6, s. 349-360
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Tidskriftsartikel (refereegranskat)abstract
- The moth Macroglossum stellatarum can learn the color and sometimes the odor of a rewarding food source. We present data from 20 different experiments with different combinations of blue and yellow artificial flowers and the two odors, honeysuckle and lavender. The experiments show that learning about the odors depends on the color used. By training on different color—odor combinations and testing on others, it becomes possible to investigate the exact relation between the two modalities during learning. Three computational models were tested in the same experimental situations as the real moths and their predictions were compared with the experimental data. The average error over all experiments as well as the largest deviation from the experimental data were calculated. Neither the Rescorla—Wagner model nor a learning model with independent learning for each stimulus component were able to explain the experimental data. We present the new hawkmoth learning model, which assumes that the moth learns a template for the sensory attributes of the rewarding stimulus. This model produces behavior that closely matches that of the real moth in all 20 experiments.
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| 5. |
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| 6. |
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| 7. |
- Balkenius, Anna, et al.
(författare)
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The relative importance of olfaction and vision in a diurnal and a nocturnal hawkmoth
- 2006
-
Ingår i: Journal of Comparative Physiology A. - : Springer Science and Business Media LLC. - 1432-1351 .- 0340-7594. ; 192:4, s. 431-437
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Tidskriftsartikel (refereegranskat)abstract
- Nectar-feeding animals can use vision and olfaction to find rewarding flowers and different species may give different weight, to the two sensory modalities. We have studied how a diurnal or nocturnal lifestyle affects the weight given to vision and olfaction. We tested naive hawkmoths of two species in a wind tunnel, presenting an odour source and a visual stimulus. Although the two species belong to the same subfamily of sphingids, the Macroglossinae, their behaviour was quite different. The nocturnal Deilephila elpenor responded preferably to the odour while the diurnal Macroglossum stellatarum strongly favoured the visual stimulus. Since a nocturnal lifestyle is ancestral for sphingids, the diurnal species, M. stellatarum, has evolved from nocturnal moths that primarily used olfaction. During bright daylight visual cues may have became more important than odour.
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| 8. |
- Beckmann, Holger, et al.
(författare)
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Spectral sensitivity in Onychophora (velvet worms) revealed by electroretinograms, phototactic behaviour and opsin gene expression.
- 2015
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 1477-9145 .- 0022-0949. ; 218:6, s. 915-922
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Tidskriftsartikel (refereegranskat)abstract
- Onychophorans typically possess a pair of simple eyes, inherited from the last common ancestor of Panarthropoda (Onychophora + Tardigrada + Arthropoda). These visual organs are thought to be homologous to the arthropod median ocelli, whereas the compound eyes most likely evolved in the arthropod lineage. To gain insights into the ancestral function and evolution of the visual system in panarthropods, we investigated phototactic behaviour, opsin gene expression and the spectral sensitivity of the eyes in two representative species of Onychophora: Euperipatoides rowelli (Peripatopsidae), and Principapillatus hitoyensis (Peripatidae). Our behavioural analyses, in conjunction with previous data, demonstrate that both species exhibit photonegative responses to wavelengths ranging from ultraviolet to green light (370-530 nm), while electroretinograms reveal that the onychophoran eye is maximally sensitive to blue light (peak sensitivity ~480 nm). Template fits to the obtained sensitivities suggest that the onychophoran eye is monochromatic. To clarify on which type of opsin the single visual pigment is based, we localised the corresponding mRNA in the onychophoran eye and brain using in situ hybridization. Our data show that the r-opsin gene (onychopsin) is expressed exclusively in the photoreceptor cells of the eye, whereas the c-opsin mRNA is confined to optic ganglion cells and the brain. Together, our findings suggest that the onychopsin is involved in vision, whereas the c-opsin might have a photoreceptive, non-visual function in onychophorans.
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| 9. |
- Bergman, Martin, et al.
(författare)
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Seeing the world through the eyes of a butterfly : visual ecology of the territorial males of Pararge aegeria (Lepidoptera: Nymphalidae)
- 2021
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Ingår i: Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology. - : Springer Science and Business Media LLC. - 0340-7594. ; 207:6, s. 701-713
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Tidskriftsartikel (refereegranskat)abstract
- Combining studies of animal visual systems with exact imaging of their visual environment can get us a step closer to understand how animals see their “Umwelt”. Here, we have combined both methods to better understand how males of the speckled wood butterfly, Pararge aegeria, see the surroundings of their perches. These males are well known to sit and wait for a chance to mate with a passing females, in sunspot territories in European forests. We provide a detailed description of the males' body and head posture, viewing direction, visual field and spatial resolution, as well as the visual environment. Pararge aegeria has sexually dimorphic eyes, the smallest interommatidial angles of males are around 1°, those of females 1.5°. Perching males face the antisolar direction with their retinal region of the highest resolution pointing at an angle of about 45° above the horizon; thus, looking at a rather even and dark background in front of which they likely have the best chance to detect a sunlit female passing through the sunspot.
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| 10. |
- Borges, Renee M., et al.
(författare)
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Patterns and processes in nocturnal and crepuscular pollination services
- 2016
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Ingår i: Quarterly Review of Biology. - : University of Chicago Press. - 0033-5770 .- 1539-7718. ; 91:4, s. 389-418
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Tidskriftsartikel (refereegranskat)abstract
- Night,dawn,and dusk have abiotic features that differ from the day. Illumination,wind speeds,turbulence,and temperatures are lower while humidity may be higher at night. Nocturnal pollination occurred in 30% of angiosperm families across 68% of orders,97% of families with C3,two-thirds of fam-ilies with crassulacean acid metabolism (CAM),and 71% dicot families with C4 photosynthesis. Despite its widespread occurence,nocturnal pollination occurs in more families with xerophytic adaptations than helophytes or mesophytes,suggesting that nocturnal flowering is primarily an adaptation to water stress since flowering is a water-intensive process. We propose the arid or water stress hypothesis for nocturnal flowering suggesting that plants facing water stress in a habitat (e.g.,deserts) or a habitat stratum (e.g.,upper canopy for epiphytes) gain a selective advantage by nocturnal flowering by reducing water loss through evapotranspiration,leading to larger flowers that provide more nectar or other resources,to support pollinators with higher rewards. Contrary to the wide taxonomic occurrence of nocturnal flowering,few animal taxa serve as nocturnal pollinators. We discuss the sensory and physiological abilities that enable pollinator movement,navigation,and detection of flowers within the nocturnal temporal niche and present a unified framework for investigation of nocturnal flowering and pollination.
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| 11. |
- Boström, Jannika E., et al.
(författare)
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The flicker fusion frequency of budgerigars (Melopsittacus undulatus) revisited
- 2017
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Ingår i: Journal of Comparative Physiology A. Sensory, neural, and behavioral physiology. - : SPRINGER. - 0340-7594 .- 1432-1351. ; 203:1, s. 15-22
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Tidskriftsartikel (refereegranskat)abstract
- While color vision and spatial resolution have been studied in many bird species, less is known about the temporal aspects of bird vision. High temporal resolution has been described in three species of passerines but it is unknown whether this is specific to passerines, to small actively flying birds, to insectivores or to birds living in bright habitats. Temporal resolution of vision is commonly tested by determining the flicker fusion frequency (FFF), at which the eye can no longer distinguish a flickering light from a constant light of equal intensity at different luminances. Using a food reward, we trained the birds to discriminate a constant light from a flickering light, at four different luminances between 750 and 7500 cd/m(2). The highest FFF found in one bird at 3500 cd/m(2) was 93 Hz. Three birds had higher FFF (82 Hz) at 7500 cd/m(2) than at 3500 cd/m(2). Six human subjects had lower FFF than the birds at 1500 but similar FFF at 750 cd/m(2). These results indicate that high temporal resolution is not a common trait for all small and active birds living in bright light habitats. Whether it is typical for passerines or for insectivorous birds remains to be tested.
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| 12. |
- Chaib, Sandra, et al.
(författare)
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Fast visual adaptation to dim light in a cavity-nesting bird
- 2023
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Ingår i: Proceedings of the Royal Society B: Biological Sciences. - 0962-8452. ; 290:1998
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Tidskriftsartikel (refereegranskat)abstract
- Many birds move fast into dark nest cavities forcing the visual system to adapt to low light intensities. Their visual system takes between 15 and 60 min for complete dark adaptation, but little is known about the visual performance of birds during the first seconds in low light intensities. In a forced two-choice behavioural experiment we studied how well budgerigars can discriminate stimuli of different luminance directly after entering a darker environment. The birds made their choices within about 1 s and did not wait to adapt their visual system to the low light intensities. When moving from a bright facility into an environment with 0.5 log unit lower illuminance, the budgerigars detected targets with a luminance of 0.825 cd m -2 on a black background. When moving into an environment with 1.7 or 3.5 log units lower illuminance, they detected targets with luminances between 0.106 and 0.136 cd m -2. In tests with two simultaneously displayed targets, the birds discriminated similar luminance differences between the targets (Weber fraction of 0.41-0.54) in all light levels. Our results support the notion that partial adaptation of bird eyes to the lower illumination occurring within 1 s allows them to safely detect and feed their chicks.
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| 13. |
- Chaib, Sandra, et al.
(författare)
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Single target acuity is not higher than grating acuity in a bird, the budgerigar
- 2019
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Ingår i: Vision Research. - : Elsevier BV. - 0042-6989. ; 160, s. 37-42
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Tidskriftsartikel (refereegranskat)abstract
- We examined the capacity of budgerigars (Melopsittacus undulatus)to visually detect dark single targets against a brighter background and established their spatial resolution limit for such targets. While the sampling density of the retina limits the resolution of gratings, target detection is theoretically limited by contrast sensitivity. This allows many animals to detect single targets smaller than their visual resolution limit, but this is not the case for budgerigars. The budgerigars were able to detect a high contrast circular target with a luminance profile of a single period of a sine wave subtending 0.065 degrees of their visual field, corresponding to a spatial acuity of 7.7 cycles degree −1 , a measurement in line with the previously measured grating acuity of budgerigars (7.7 and 10 cycles degree −1 ). This result is different from findings on the spatial acuity of humans, who can detect single targets much smaller than predicted by their acuity for gratings. The low contrast sensitivity of budgerigar vision might be one of the reasons why the single target acuity is not higher than grating acuity. Adding a bright surround to the target did not influence detection threshold significantly. However, the threshold was slightly higher for a target with a square-wave luminance profile than for a target with a sinusoidal luminance profile.
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| 14. |
- Chaib, Sandra, et al.
(författare)
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Visual acuity of budgerigars for moving targets
- 2021
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Ingår i: Biology Open. - : The Company of Biologists. - 2046-6390. ; 10:9
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Tidskriftsartikel (refereegranskat)abstract
- For a bird, it is often vital to visually detect food items, predators, or individuals from the same flock, i.e. moving stimuli of various shapes. Yet, behavioural tests of visual spatial acuity traditionally use stationary gratings as stimuli. We have behaviourally tested the ability of budgerigars (Melopsittacus undulatus) to detect a black circular target, moving semi-randomly at 1.69 degrees s−1 against a brighter background. We found a detection threshold of 0.107±0.007 degrees of the visual field for a target size corresponding to a resolution of a grating with a spatial frequency of 4.68 cycles degree−1. This detection threshold is lower than the resolution limit for gratings but similar to the threshold for stationary single objects of the same shape. We conclude that the target acuity of budgerigars for moving single targets, just as for stationary single targets, is lower than their acuity for gratings.
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| 15. |
- Chakravarthi, Aravin, et al.
(författare)
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Differences in spatial resolution and contrast sensitivity of flight control in the honeybees Apis cerana and Apis mellifera
- 2018
-
Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 221:20
-
Tidskriftsartikel (refereegranskat)abstract
- Visually guided behaviour is constrained by the capacity of the visual system to resolve detail. This, in turn, is limited by the spatial resolution and contrast sensitivity of the underlying visual system. Because these properties are interdependent and vary nonuniformly, it is only possible to fully understand the limits of a specific visually guided behaviour when they are investigated in combination. To understand the visual limits of flight control in bees, which rely heavily on vision to control flight, and to explore whether they vary between species, we tested how changes in spatial resolution and contrast sensitivity affect the speed and position control of the Asian and European honeybees (Apis cerana and Apis mellifera). Despite the apparent similarity of these species, we found some interesting and surprising differences between their visual limits. While the effect of spatial frequency and contrast on position control is similar between the species, ground speed is differently affected by these variables. A comparison with published data from the bumblebee Bombus terrestris revealed further differences. The visual resolution that limits the detection and use of optic flow for flight control in both species of honeybee is lower than the previously anatomically determined resolution and differs from object detection limits of A. mellifera, providing evidence that the limits of spatial resolution and contrast sensitivity are highly tuned to the particular behavioural task of a species.
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| 16. |
- Chakravarthi, Aravin, et al.
(författare)
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High contrast sensitivity for visually guided flight control in bumblebees
- 2017
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Ingår i: Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology. - : Springer Science and Business Media LLC. - 1432-1351. ; 203:12, s. 999-1006
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Tidskriftsartikel (refereegranskat)abstract
- Many insects rely on vision to find food, to return to their nest and to carefully control their flight between these two locations. The amount of information available to support these tasks is, in part, dictated by the spatial resolution and contrast sensitivity of their visual systems. Here, we investigate the absolute limits of these visual properties for visually guided position and speed control in Bombus terrestris. Our results indicate that the limit of spatial vision in the translational motion detection system of B. terrestris lies at 0.21 cycles deg−1 with a peak contrast sensitivity of at least 33. In the perspective of earlier findings, these results indicate that bumblebees have higher contrast sensitivity in the motion detection system underlying position control than in their object discrimination system. This suggests that bumblebees, and most likely also other insects, have different visual thresholds depending on the behavioral context.
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| 17. |
- Chakravarthi, Aravin, et al.
(författare)
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How well can bees see the world?
- 2016
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Ingår i: Navigation News. - 0268-6317. ; MAR/APR 2016, s. 10-10
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 18. |
- Chakravarthi, Aravin, et al.
(författare)
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Spatial Vision in Bombus terrestris.
- 2016
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Ingår i: Frontiers in Behavioral Neuroscience. - : Frontiers Media SA. - 1662-5153. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Bombus terrestris is one of the most commonly used insect models to investigate visually guided behavior and spatial vision in particular. Two fundamental measures of spatial vision are spatial resolution and contrast sensitivity. In this study, we report the threshold of spatial resolution in B. terrestris and characterize the contrast sensitivity function of the bumblebee visual system for a dual choice discrimination task. We trained bumblebees in a Y-maze experimental set-up to associate a vertical sinusoidal grating with a sucrose reward, and a horizontal grating with absence of a reward. Using a logistic psychometric function, we estimated a resolution threshold of 0.21 cycles deg(-1) of visual angle. This resolution is in the same range but slightly lower than that found in honeybees (Apis mellifera and A. cerana) and another bumblebee species (B. impatiens). We also found that the contrast sensitivity of B. terrestris was 1.57 for the spatial frequency 0.090 cycles deg(-1) and 1.26 for 0.18 cycles deg(-1).
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| 19. |
- Chavez, Johanna, et al.
(författare)
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Unexpectedly low UV-sensitivity in a bird, the budgerigar.
- 2014
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Ingår i: Biology letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 10:11
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Tidskriftsartikel (refereegranskat)abstract
- Photoreceptor adaptation ensures appropriate visual responses during changing light conditions and contributes to colour constancy. We used behavioural tests to compare UV-sensitivity of budgerigars after adaptation to UV-rich and UV-poor backgrounds. In the latter case, we found lower UV-sensitivity than expected, which could be the result of photon-shot noise corrupting cone signal robustness or nonlinear background adaptation. We suggest that nonlinear adaptation may be necessary for allowing cones to discriminate UV-rich signals, such as bird plumage colours, against UV-poor natural backgrounds.
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| 20. |
- Cuthill, Innes C., et al.
(författare)
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The biology of color
- 2017
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 357:6350
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Forskningsöversikt (refereegranskat)abstract
- Coloration mediates the relationship between an organism and its environment in important ways, including social signaling, antipredator defenses, parasitic exploitation, thermoregulation, and protection from ultraviolet light, microbes, and abrasion. Methodological breakthroughs are accelerating knowledge of the processes underlying both the production of animal coloration and its perception, experiments are advancing understanding of mechanism and function, and measurements of color collected noninvasively and at a global scale are opening windows to evolutionary dynamics more generally. Here we provide a roadmap of these advances and identify hitherto unrecognized challenges for this multi- and interdisciplinary field.
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| 21. |
- Dahake, Ajinkya, et al.
(författare)
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The roles of vision and antennal mechanoreception in hawkmoth flight control
- 2018
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Ingår i: eLife. - 2050-084X. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Flying animals need continual sensory feedback about their body position and orientation for flight control. The visual system provides essential but slow feedback. In contrast, mechanosensory channels can provide feedback at much shorter timescales. How the contributions from these two senses are integrated remains an open question in most insect groups. In Diptera, fast mechanosensory feedback is provided by organs called halteres and is crucial for the control of rapid flight manoeuvres, while vision controls manoeuvres in lower temporal frequency bands. Here, we have investigated the visual-mechanosensory integration in the hawkmoth Macroglossum stellatarum. They represent a large group of insects that use Johnston's organs in their antennae to provide mechanosensory feedback on perturbations in body position. Our experiments show that antennal mechanosensory feedback specifically mediates fast flight manoeuvres, but not slow ones. Moreover, we did not observe compensatory interactions between antennal and visual feedback.
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| 22. |
- Gilmour, Kathleen M., et al.
(författare)
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Through the looking glass : attempting to predict future opportunities and challenges in experimental biology
- 2023
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Ingår i: The Journal of experimental biology. - 1477-9145. ; 226:24
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Tidskriftsartikel (refereegranskat)abstract
- To celebrate its centenary year, Journal of Experimental Biology (JEB) commissioned a collection of articles examining the past, present and future of experimental biology. This Commentary closes the collection by considering the important research opportunities and challenges that await us in the future. We expect that researchers will harness the power of technological advances, such as '-omics' and gene editing, to probe resistance and resilience to environmental change as well as other organismal responses. The capacity to handle large data sets will allow high-resolution data to be collected for individual animals and to understand population, species and community responses. The availability of large data sets will also place greater emphasis on approaches such as modeling and simulations. Finally, the increasing sophistication of biologgers will allow more comprehensive data to be collected for individual animals in the wild. Collectively, these approaches will provide an unprecedented understanding of 'how animals work' as well as keys to safeguarding animals at a time when anthropogenic activities are degrading the natural environment.
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| 23. |
- Goyret, Joaquin, et al.
(författare)
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Chromatic Signals Control Proboscis Movements during Hovering Flight in the Hummingbird Hawkmoth Macroglossum stellatarum.
- 2012
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:4
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Tidskriftsartikel (refereegranskat)abstract
- Most visual systems are more sensitive to luminance than to colour signals. Animals resolve finer spatial detail and temporal changes through achromatic signals than through chromatic ones. Probably, this explains that detection of small, distant, or moving objects is typically mediated through achromatic signals. Macroglossum stellatarum are fast flying nectarivorous hawkmoths that inspect flowers with their long proboscis while hovering. They can visually control this behaviour using floral markings known as nectar guides. Here, we investigate whether this is mediated by chromatic or achromatic cues. We evaluated proboscis placement, foraging efficiency, and inspection learning of naïve moths foraging on flower models with coloured markings that offered either chromatic, achromatic or both contrasts. Hummingbird hawkmoths could use either achromatic or chromatic signals to inspect models while hovering. We identified three, apparently independent, components controlling proboscis placement: After initial contact, 1) moths directed their probing towards the yellow colour irrespectively of luminance signals, suggesting a dominant role of chromatic signals; and 2) moths tended to probe mainly on the brighter areas of models that offered only achromatic signals. 3) During the establishment of the first contact, naïve moths showed a tendency to direct their proboscis towards the small floral marks independent of their colour or luminance. Moths learned to find nectar faster, but their foraging efficiency depended on the flower model they foraged on. Our results imply that M. stellatarum can perceive small patterns through colour vision. We discuss how the different informational contents of chromatic and luminance signals can be significant for the control of flower inspection, and visually guided behaviours in general.
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| 24. |
- Goyret, Joaquin, et al.
(författare)
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Flexible responses to visual and olfactory stimuli by foraging Manduca sexta: larval nutrition affects adult behaviour
- 2009
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Ingår i: Royal Society of London. Proceedings B. Biological Sciences. - : The Royal Society. - 1471-2954. ; 276:1668, s. 2739-2745
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Tidskriftsartikel (refereegranskat)abstract
- Here, we show that the consequences of deficient micronutrient (beta-carotene) intake during larval stages of Manduca sexta are carried across metamorphosis, affecting adult behaviour. Our manipulation of larval diet allowed us to examine how developmental plasticity impacts the interplay between visual and olfactory inputs on adult foraging behaviour. Larvae of M. sexta were reared on natural (Nicotiana tabacum) and artificial laboratory diets containing different concentrations of beta-carotene (standard diet, low beta-carotene, high beta-carotene and cornmeal). This vitamin-A precursor has been shown to be crucial for photoreception sensitivity in the retina of M. sexta. After completing development, post-metamorphosis, starved adults were presented with artificial feeders that could be either scented or unscented. Regardless of their larval diet, adult moths fed with relatively high probabilities on scented feeders. When feeders were unscented, moths reared on tobacco were more responsive than moths reared on beta-carotene-deficient artificial diets. Strikingly, moths reared on artificial diets supplemented with increasing amounts of beta-carotene (low beta and high beta) showed increasing probabilities of response to scentless feeders. We discuss these results in relationship to the use of complex, multi-modal sensory information by foraging animals.
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| 25. |
- Goyret, Joaquin, et al.
(författare)
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How does a diurnal hawkmoth find nectar? Differences in sensory control with a nocturnal relative
- 2011
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 22:5, s. 976-984
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Tidskriftsartikel (refereegranskat)abstract
- Recent research shows that a nocturnal hawkmoth, Manduca sexta, inspects flowers in search for nectar by means of a series of hovering and proboscis movements controlled by different sensory modalities, mainly vision and mechanoreception. The diurnal Macroglossum stellatarum is a closely related hawkmoth challenged with the same task but under illuminances 6-8 orders of magnitude higher. Here, we use flower models presenting color markings, 3D features, or both to study innate flower movements and sensory cues involved in the innate inspection behavior of M. stellatarum. On flat plain colored models, moths scanned the whole corolla with their proboscis, attaining intermediate success levels. When models presented color markings, moths biased proboscis placement, which affected inspection efficiency. Three-dimensional features affected inspection behavior and efficiency, by provoking strong "diving'' responses. When both visual and tactile features were present, visual cues showed prevalence in the control of the inspection behavior. We evaluated learning abilities of moths, finding that M. stellatarum cannot only improve their efficiency by calibrating innate responses but also by changing their innate strategy. We discuss results on flower inspection behavior of M. stellatarum comparatively with known aspects of this behavior in M. sexta. Motor responses appear to be shared by these hawkmoths, but their sensory control shows important differences. Future studies will evaluate whether these differences are the result of an evolutionary divergence of their innate behavior associated with a switch to diurnal activity or the result of a flexible use of sensory information by the naive animals.
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| 26. |
- Goyret, Joaquin, et al.
(författare)
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Why do Manduca sexta feed from white flowers? Innate and learnt colour preferences in a hawkmoth
- 2008
-
Ingår i: Naturwissenschaften. - : Springer Science and Business Media LLC. - 1432-1904 .- 0028-1042. ; 95:6, s. 569-576
-
Tidskriftsartikel (refereegranskat)abstract
- Flower colour is an important signal used by flowering plants to attract pollinators. Many anthophilous insects have an innate colour preference that is displayed during their first foraging bouts and which could help them locate their first nectar reward. Nevertheless, learning capabilities allow insects to switch their colour preferences with experience and thus, to track variation in floral nectar availability. Manduca sexta, a crepuscular hawkmoth widely studied as a model system for sensory physiology and behaviour, visits mostly white, night-blooming flowers lacking UV reflectance throughout its range in the Americas. Nevertheless, the spectral sensitivity of the feeding behaviour of naive moths shows a narrow peak around 450 nm wavelengths, suggesting an innate preference for the colour blue. Under more natural conditions (i.e. broader wavelength reflectance) than in previous studies, we used dual choice experiments with blue- and white-coloured feeders to investigate the innate preference of naive moths and trained different groups to each colour to evaluate their learning capabilities. We confirmed the innate preference of M. sexta for blue and found that these moths were able to switch colour preferences after training experience. These results unequivocally demonstrate that M. sexta moths innately prefer blue when presented against white flower models and offer novel experimental evidence supporting the hypothesis that learning capabilities could be involved in their foraging preferences, including their widely observed attraction to white flowers in nature.
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| 27. |
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| 28. |
- Haller, Nicola, et al.
(författare)
-
Stimulus motion improves spatial contrast sensitivity in budgerigars (Melopsittacus undulatus).
- 2014
-
Ingår i: Vision Research. - : Elsevier BV. - 1878-5646 .- 0042-6989. ; 102, s. 19-25
-
Tidskriftsartikel (refereegranskat)abstract
- Birds are generally thought to have excellent vision with high spatial resolution. However, spatial contrast sensitivity of birds for stationary targets is low compared to other animals with similar acuity, such as mammals. For fast flying animals body stability and coordination are highly important, and visual motion cues are known to be relevant for flight control. We have tested five budgerigars (Melopsittacus undulatus) in behavioural discrimination experiments to determine whether or not stimulus motion improves contrast sensitivity. The birds were trained to distinguish between a homogenous grey field and sine-wave gratings of spatial frequencies between 0.48 and 6.5 cycles/degree, and Michelson contrasts between 0.7% and 99%. The gratings were either stationary or drifting with velocities between 0.9 and 13 degrees/s. Budgerigars were able to discriminate patterns of lower contrast from grey when the gratings were drifting, and the improvement in sensitivity was strongest at lower spatial frequencies and higher drift velocities. Our findings indicate that motion cues can have positive effects on visual perception of birds. This is similar to earlier results on human vision. Contrast sensitivity, tested solely with stationary stimuli, underestimates the sensory capacity of budgerigars flying through their natural environments.
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| 29. |
- Hanke, Frederike D., et al.
(författare)
-
The Eye of the Common Octopus (Octopus vulgaris)
- 2020
-
Ingår i: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 10
-
Forskningsöversikt (refereegranskat)abstract
- Octopus vulgaris, well-known from temperate waters of the Mediterranean Sea and a well-cited model species among the cephalopods, has large eyes with which it scans its environment actively and which allow the organism to discriminate objects easily. On cursory examination, the single-chambered eyes of octopus with their spherical lenses resemble vertebrate eyes. However there are also apparent differences. For example, the retina of the octopus is everted instead of inverted, and it is equipped with primary rhabdomeric photoreceptors rather than secondary ciliary variety found in the retina of the vertebrate eye. The eyes of octopus are well adapted to the habitat and lifestyle of the species; the pupil closes quickly as a response to sudden light stimuli mimicking a situation in which the octopus leaves its den in shallow water during daytime. Although the many general anatomical and physiological features of octopus vision have been described elsewhere, our review reveals that a lot of information is still missing. Investigations that remain to be undertaken include a detailed examination of the dioptric apparatus or the visual functions such as brightness discrimination as well as a conclusive test for a faculty analogous to, or in lieu of, color vision. For a better understanding of the octopus eye and the functions mediated by it, we suggest that future studies focus on knowledge gaps that we outline in the present review.
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| 30. |
- Henze, Miriam J., et al.
(författare)
-
An aposematic colour-polymorphic moth seen through the eyes of conspecifics and predators - Sensitivity and colour discrimination in a tiger moth
- 2018
-
Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 32:7, s. 1797-1809
-
Tidskriftsartikel (refereegranskat)abstract
- Although predation is commonly thought to exert the strongest selective pressure on coloration in aposematic species, sexual selection may also influence coloration. Specifically, polymorphism in aposematic species cannot be explained by natural selection alone. Males of the aposematic wood tiger moth (Arctia plantaginis) are polymorphic for hindwing coloration throughout most of their range. In Scandinavia, they display either white or yellow hindwings. Female hindwing coloration varies continuously from bright orange to red. Redder females and yellow males suffer least from bird predation. White males often have higher mating success than yellow males. Therefore, we ask whether females can discriminate the two male morphs by colour. Males approach females by following pheromone plumes from a distance, but search visually at short range. This raises the questions whether males discriminate female coloration and, in turn, whether female coloration is also sexually selected. Using electroretinograms, we found significantly larger retinal responses in male than female A. plantaginis, but similar spectral sensitivities in both sexes, with peaks in the UV (349 nm), blue (457 nm) and green (521 nm) wavelength range. According to colour vision models, conspecifics can discriminate white and yellow males as separate morphs, but not orange and red females. For moths and birds (Cyanistes caeruleus), white males are more conspicuous against green and brown backgrounds, mostly due to UV reflectivity, and red females are slightly more conspicuous than orange females. The costly red coloration among females is likely selected by predator pressure, not by conspecifics, whereas male colour polymorphism is probably maintained, at least partly, by the opposing forces of predation pressure favouring yellow males, and female preference for white males. Whether or not the preference for white males is based on visual cues requires further testing. The evolution of polymorphic aposematic animals can be better understood when the visual system of the species and their predators is taken into consideration. A plain language summary is available for this article.
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| 31. |
- Henze, Miriam J., et al.
(författare)
-
Pterin-pigmented nanospheres create the colours of the polymorphic damselfly Ischnura elegans
- 2019
-
Ingår i: Journal of the Royal Society, Interface. - : The Royal Society. - 1742-5662 .- 1742-5689. ; 16:153
-
Tidskriftsartikel (refereegranskat)abstract
- Animal colours commonly act as signals for mates or predators. In many damselfly species, both sexes go through a developmental colour change as adults, and females often show colour polymorphism, which may have a function in mate choice, avoidance of mating harassment and camouflage. In the blue-tailed damselfly, Ischnura elegans, young males are bright green and turn blue as they reach maturity. Females are red ( rufescens) or violet ( violacea) as immatures and, when mature, either mimic the blue colour of the males ( androchrome), or acquire an inconspicuous olive-green ( infuscans) or olive-brown ( obsoleta). The genetic basis of these differences is still unknown. Here, we quantify the colour development of all morphs of I. elegans and investigate colour formation by combining anatomical data and reflectance spectra with optical finite-difference time-domain simulations. While the coloration primarily arises from a disordered assembly of nanospheres in the epidermis, morph-dependent changes result from adjustments in the composition of pterin pigments within the nanospheres, and from associated shifts in optical density. Other pigments fine-tune hue and brilliance by absorbing stray light. These mechanisms produce an impressive palette of colours and offer guidance for genetic studies on the evolution of colour polymorphism and visual communication.
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| 32. |
- Hering, Lars, et al.
(författare)
-
Opsins in Onychophora (Velvet Worms) Suggest a Single Origin and Subsequent Diversification of Visual Pigments in Arthropods
- 2012
-
Ingår i: Molecular biology and evolution. - : Oxford University Press (OUP). - 0737-4038 .- 1537-1719. ; 29:11, s. 3451-3458
-
Tidskriftsartikel (refereegranskat)abstract
- Multiple visual pigments, prerequisites for color vision, are found in arthropods, but the evolutionary origin of their diversity remains obscure. In this study, we explore the opsin genes in five distantly related species of Onychophora, using deep transcriptome sequencing and screening approaches. Surprisingly, our data reveal the presence of only one opsin gene (onychopsin) in each onychophoran species, and our behavioral experiments indicate a maximum sensitivity of onychopsin to blue-green light. In our phylogenetic analyses, the onychopsins represent the sister group to the monophyletic clade of visual r-opsins of arthropods. These results concur with phylogenomic support for the sister-group status of the Onychophora and Arthropoda and provide evidence for monochromatic vision in velvet worms and in the last common ancestor of Onychophora and Arthropoda. We conclude that the diversification of visual pigments and color vision evolved in arthropods, along with the evolution of compound eyes-one of the most sophisticated visual systems known.
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| 33. |
- Höglund, Julia, et al.
(författare)
-
Owls lack UV-sensitive cone opsin and red oil droplets, but see UV light at night : Retinal transcriptomes and ocular media transmittance
- 2019
-
Ingår i: Vision Research. - : Elsevier BV. - 0042-6989 .- 1878-5646. ; 158, s. 109-119
-
Tidskriftsartikel (refereegranskat)abstract
- Most diurnal birds have cone-dominated retinae and tetrachromatic colour vision based on ultra-violet/violet-sensitive UV/V cones expressing short wavelength-sensitive opsin 1 (SWS1), S cones expressing short wavelength-sensitive opsin 2 (SWS2), M cones expressing medium wavelength-sensitive opsin (RH2) and L cones expressing long wavelength-sensitive opsin (LWS). Double cones (D) express LWS but do not contribute to colour vision. Each cone is equipped with an oil droplet, transparent in UV/V cones, but pigmented by carotenoids: galloxanthin in S, zeaxanthin in M, astaxanthin in L and a mixture in D cones. Owls (Strigiformes) are crepuscular or nocturnal birds with rod-dominated retinae and optical adaptations for high sensitivity. For eight species, the absence of functional SWS1 opsin has recently been documented, functional RH2 opsin was absent in three of these. Here we confirm the absence of SWS1 transcripts for the Long-eared owl (Asio otus) and demonstrate its absence for the Short-eared owl (Asio flammeus), Tawny owl (Strix aluco) and Boreal owl (Aegolius funereus). All four species had transcripts of RH2, albeit with low expression. All four species express all enzymes needed to produce galloxanthin, but lack CYP2J19 expression required to produce astaxanthin from dietary precursors. We also present ocular media transmittance of the Eurasian eagle owl (Bubo bubo) and Short-eared owl and predict spectral sensitivities of all photoreceptors of the Tawny owl. We conclude that owls, despite lacking UV/V cones, can detect UV light. This increases the sensitivity of their rod vision allowing them, for instance, to see UV-reflecting feathers as brighter signals at night.
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| 34. |
- Jezeera, M. Asmi, et al.
(författare)
-
Spatial resolution and sensitivity of the eyes of the stingless bee, Tetragonula iridipennis
- 2022
-
Ingår i: Journal of Comparative Physiology A. Sensory, neural, and behavioral physiology. - : Springer Science and Business Media LLC. - 0340-7594 .- 1432-1351. ; 208:2, s. 225-238
-
Tidskriftsartikel (refereegranskat)abstract
- Stingless bees are important pollinators in the tropics. The tremendous variation in body size makes them an excellent group to study how miniaturization affects vision and visual behaviours. Using direct measurements and micro-CT, we reconstructed the eye structure, estimated anatomical spatial resolution and optical sensitivity of the stingless bee Tetragonula iridipennis. T. iridipennis is similar in size to the Australian stingless bee Tetragonula carbonaria and is smaller than honeybees. It has correspondingly small eyes (area = 0.56 mm2), few ommatidia (2451 ± 127), large inter-facet (3.0 ± 0.6°) and acceptance angles (2.8°). Theoretical estimates suggest that T. iridipennis has poorer spatial resolution (0.17 cycles degree−1) than honeybees, bumblebees, and T. carbonaria. Its optical sensitivity (0.08 µm2 sr), though higher than expected, is within the range of diurnal bees. This may provide them with greater contrast sensitivity, which is likely more relevant than the absolute sensitivity in this diurnal bee. Behaviourally determined detection thresholds for single targets using y-maze experiments were 11.5° for targets that provide chromatic contrast alone and 9.1° for targets providing chromatic and achromatic contrast. Further studies into microhabitat preferences and behaviour are required to understand how miniaturization influences its visual ecology.
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| 35. |
- Johansson, Christoffer, et al.
(författare)
-
Multiple leading edge vortices of unexpected strength in freely flying hawkmoth.
- 2013
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 3
-
Tidskriftsartikel (refereegranskat)abstract
- The Leading Edge Vortex (LEV) is a universal mechanism enhancing lift in flying organisms. LEVs, generally illustrated as a single vortex attached to the wing throughout the downstroke, have not been studied quantitatively in freely flying insects. Previous findings are either qualitative or from flappers and tethered insects. We measure the flow above the wing of freely flying hawkmoths and find multiple simultaneous LEVs of varying strength and structure along the wingspan. At the inner wing there is a single, attached LEV, while at mid wing there are multiple LEVs, and towards the wingtip flow separates. At mid wing the LEV circulation is ~40% higher than in the wake, implying that the circulation unrelated to the LEV may reduce lift. The strong and complex LEV suggests relatively high flight power in hawmoths. The variable LEV structure may result in variable force production, influencing flight control in the animals.
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| 36. |
- Johnsen, S, et al.
(författare)
-
Crepuscular and nocturnal illumination and its effects on color perception by the nocturnal hawkmoth Deilephila elpenor
- 2006
-
Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 1477-9145 .- 0022-0949. ; 209:5, s. 789-800
-
Tidskriftsartikel (refereegranskat)abstract
- Recent studies have shown that certain nocturnal insect and vertebrate species have true color vision under nocturnal illumination. Thus, their vision is potentially affected by changes in the spectral quality of twilight and nocturnal illumination, due to the presence or absence of the moon, artificial light pollution and other factors. We investigated this in the following manner. First we measured the spectral irradiance (from 300 to 700 nm) during the day, sunset, twilight, full moon, new moon, and in the presence of high levels of light pollution. The spectra were then converted to both human-based chromaticities and to relative quantum catches for the nocturnal hawkmoth Dedephila elpenor, which has color vision. The reflectance spectra of various flowers and leaves and the red hindwings of D. elpenor were also converted to chromaticities and relative quantum catches. Finally, the achromatic and chromatic contrasts (with and without von Kries color constancy) of the flowers and hindwings against a leaf background were determined under the various lighting environments. The twilight and nocturnal illuminants; were substantially different from each other, resulting in significantly different contrasts. The addition of von Kries color constancy significantly reduced the effect of changing illuminants; on chromatic contrast, suggesting that, even in this light-limited environment, the ability of color vision to provide reliable signals under changing illuminants; may offset the concurrent threefold decrease in sensitivity and spatial resolution. Given this, color vision may be more common in crepuscular and nocturnal species than previously considered.
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| 37. |
- Kelber, Almut
(författare)
-
Alternative use of chromatic and achromatic cues in a hawkmoth
- 2005
-
Ingår i: Royal Society of London. Proceedings B. Biological Sciences. - : The Royal Society. - 1471-2954. ; 272:1577, s. 2143-2147
-
Tidskriftsartikel (refereegranskat)abstract
- The diurnal hummingbird hawkmoth Macroglossum stellatarum can learn the achromatic (intensity-related) and the chromatic (wavelength-related) aspect of a spectral colour. Free-flying moths learn to discriminate two colours differing in the chromatic aspect of colour fast and with high precision. In contrast, they learn the discrimination of two stimuli differing in the achromatic aspect more slowly and less reliably. When trained to use the chromatic aspect, they disregard the achromatic aspect, and when trained to use the achromatic aspect, they disregard the chromatic aspect, at least to some degree. In a conflicting situation, hummingbird hawkmoths clearly rely on the chromatic aspect of colour. Generally, the moths pay attention to the most reliable cue that allows them to discriminate colours in the learning situation. This is usually the chromatic aspect of the colour but they can learn to attend to the achromatic aspect instead. There is no evidence for relative colour learning, i.e. moths do not learn to choose the longer or shorter of two wavelengths, but it is possible that they learn to choose the darker or brighter shade of a colour, and thereby its relative intensities.
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| 38. |
- Kelber, Almut, et al.
(författare)
-
Animal colour vision - behavioural tests and physiological concepts
- 2003
-
Ingår i: Biological Reviews. - 1469-185X. ; 78:1, s. 81-118
-
Forskningsöversikt (refereegranskat)abstract
- Over a century ago workers such as J. Lubbock and K. von Frisch developed behavioural criteria for establishing that non-human animals see colour. Many animals in most phyla have since then been shown to have colour vision. Colour is used for specific behaviours, such as phototaxis and object recognition, while other behaviours such as motion detection are colour blind. Having established the existence of colour vision, research focussed on the question of how many spectral types of photoreceptors are involved. Recently, data on photoreceptor spectral sensitivities have been combined with behavioural experiments and physiological models to study systematically the next logical question: what neural interactions underlie colour vision? This review gives an overview of the methods used to study animal colour vision, and discusses how quantitative modelling can suggest how photoreceptor signals are combined and compared to allow for the discrimination of biologically relevant stimuli.
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| 39. |
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| 40. |
- Kelber, Almut
(författare)
-
Bird colour vision – from cones to perception
- 2019
-
Ingår i: Current Opinion in Behavioral Sciences. - : Elsevier BV. - 2352-1554 .- 2352-1546. ; 30, s. 34-40
-
Forskningsöversikt (refereegranskat)abstract
- Birds use spectral information for circadian control, magnetic orientation and phototaxis but most importantly for discriminating the colours of important objects such as food items or mates. Their tetrachromatic colour vision is based on four types of single cones expressing four opsin-based visual pigments and fine-tuned by the carotenoid composition in cone oil droplets. Bird colour vision is not as uniform as previously thought, and single visual pigments have been lost in several bird lineages. Diurnal birds have fine colour discrimination and good colour constancy but can generalize over similar though discriminable colours. Bird colour discrimination is ultimately limited by receptor noise but can be impaired in natural conditions, depending on light intensity and background coloration.
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| 41. |
- Kelber, Almut
(författare)
-
Birds perceive colours in categories
- 2018
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 560, s. 311-312
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Humans perceive colours in categories such as red, even though we can discernred hues including ruby and crimson. It emerges that birds also categorizecolours and this affects their colour-discrimination ability.
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| 42. |
- Kelber, Almut
(författare)
-
Colour in the eye of the beholder : receptor sensitivities and neural circuits underlying colour opponency and colour perception
- 2016
-
Ingår i: Current Opinion in Neurobiology. - : Elsevier BV. - 0959-4388. ; 41, s. 106-112
-
Forskningsöversikt (refereegranskat)abstract
- Colour vision — the ability to discriminate spectral differences irrespective of variations in intensity — has two basic requirements: (1) photoreceptors with different spectral sensitivities, and (2) neural comparison of signals from these photoreceptors. Major progress has been made understanding the evolution of the basic stages of colour vision–opsin pigments, screening pigments, and the first neurons coding chromatic opponency, and similarities between mammals and insects point to general mechanisms. However, much work is still needed to unravel full colour pathways in various animals. While primates may have brain regions entirely dedicated to colour coding, animals with small brains, such as insects, likely combine colour information directly in parallel multisensory pathways controlling various behaviours.
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| 43. |
- Kelber, Almut, et al.
(författare)
-
Colour vision in diurnal and nocturnal hawkmoths
- 2003
-
Ingår i: Integrative and Comparative Biology. - : Oxford University Press (OUP). - 1557-7023 .- 1540-7063. ; 43:4, s. 571-579
-
Tidskriftsartikel (refereegranskat)abstract
- Diurnal and nocturnal hawkmoths (Sphingidae, Lepidoptera) have three spectral types of receptor sensitive to ultraviolet, blue and green light. As avid flower visitors and pollinators, they use olfactory and visual cues to find and recognise flowers. Moths of the diurnal species Macroglossum stellatarum and the nocturnal species Deilephila elpenor, Hyles lineata and Hyles gallii use and learn the colour of flowers. Nocturnal species can discriminate flowers at starlight intensities when humans and honeybees are colour-blind. M. stellatarum can use achromatic, intensity-related cues if colour cues are absent, and this is probably also true for D. elpenor. Both species can recognise colours even under a changed illumination colour.
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| 44. |
- Kelber, Almut, et al.
(författare)
-
Colour vision: parallel pathways intersect in Drosophila.
- 2013
-
Ingår i: Current Biology. - : Elsevier BV. - 1879-0445 .- 0960-9822. ; 23:23, s. 1043-1045
-
Tidskriftsartikel (refereegranskat)abstract
- In the last one hundred years, colour vision has been demonstrated in bees and many other insects. But the underlying neural wiring remained elusive. A new study on Drosophila melanogaster combining behavioural and genetic tools yields surprising insights.
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| 45. |
- Kelber, Almut
(författare)
-
Colour Vision : Random Retina of Butterflies Explained
- 2016
-
Ingår i: Current Biology. - : Elsevier BV. - 0960-9822. ; 26:19, s. 900-902
-
Tidskriftsartikel (refereegranskat)abstract
- Butterfly eyes are random mosaics built of three ommatidia types, each with a different set of photoreceptors and pigments. What defines the combined features in each ommatidium? A new study has solved the puzzle.
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| 46. |
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| 47. |
- Kelber, Almut, et al.
(författare)
-
Evolution of color vision
- 2016
-
Ingår i: Human Colour Vision. - Cham : Springer International Publishing. - 9783319449760 - 9783319449784 ; 5, s. 317-354
-
Bokkapitel (refereegranskat)abstract
- Research conducted in recent years has documented the widespread presence of various forms of color vision in species from across the animal kingdom, helped to develop an understanding of the basic biological mechanisms that underlie this sensory capacity, and provided some insights into the utility of color vision in the natural world. This chapter draws information from all these various sources to reveal what has been learned about the evolution of color vision. In doing so, we examine the extent and nature of animal color vision, describe various structural features of eyes and photoreceptors that condition color vision, look at photopigment opsin genes and their color vision concomitants, and comment on specific cases where progress has been made toward understanding the functional utility of color vision. Although results from a wide range of different species are considered, we focus particular attention on issues relevant to the evolution of vertebrate color vision.
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| 48. |
- Kelber, Almut, et al.
(författare)
-
From spectral information to animal colour vision: experiments and concepts.
- 2010
-
Ingår i: Proceedings of the Royal Society B: Biological Sciences. - : The Royal Society. - 1471-2954 .- 0962-8452. ; 277, s. 1617-1625
-
Tidskriftsartikel (refereegranskat)abstract
- Many animals use the spectral distribution of light to guide behaviour, but whether they have colour vision has been debated for over a century. Our strong subjective experience of colour and the fact that human vision is the paradigm for colour science inevitably raises the question of how we compare with other species. This article outlines four grades of 'colour vision' that can be related to the behavioural uses of spectral information, and perhaps to the underlying mechanisms. In the first, even without an (image-forming) eye, simple organisms can compare photoreceptor signals to locate a desired light environment. At the next grade, chromatic mechanisms along with spatial vision guide innate preferences for objects such as food or mates; this is sometimes described as wavelength-specific behaviour. Here, we compare the capabilities of di- and trichromatic vision, and ask why some animals have more than three spectral types of receptors. Behaviours guided by innate preferences are then distinguished from a grade that allows learning, in part because the ability to learn an arbitrary colour is evidence for a neural representation of colour. The fourth grade concerns colour appearance rather than colour difference: for instance, the distinction between hue and saturation, and colour categorization. These higher-level phenomena are essential to human colour perception but poorly known in animals, and we suggest how they can be studied. Finally, we observe that awareness of colour and colour qualia cannot be easily tested in animals.
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| 49. |
- Kelber, Almut, et al.
(författare)
-
Hornets Can Fly at Night without Obvious Adaptations of Eyes and Ocelli.
- 2011
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:7
-
Tidskriftsartikel (refereegranskat)abstract
- Hornets, the largest social wasps, have a reputation of being facultatively nocturnal. Here we confirm flight activity of hornet workers in dim twilight. We studied the eyes and ocelli of European hornets (Vespa crabro) and common wasps (Vespula vulgaris) with the goal to find the optical and anatomical adaptations that enable them to fly in dim light. Adaptations described for obligately nocturnal hymenoptera such as the bees Xylocopa tranquebarica and Megalopta genalis and the wasp Apoica pallens include large ocelli and compound eyes with wide rhabdoms and large facet lenses. Interestingly, we did not find any such adaptations in hornet eyes or ocelli. On the contrary, their eyes are even less sensitive than those of the obligately diurnal common wasps. Therefore we conclude that hornets, like several facultatively nocturnal bee species such as Apis mellifera adansonii, A. dorsata and X. tenuiscapa are capable of seeing in dim light simply due to the large body and thus eye size. We propose that neural pooling strategies and behavioural adaptations precede anatomical adaptations in the eyes and ocelli when insects with apposition compound eyes turn to dim light activity.
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| 50. |
- Kelber, Almut
(författare)
-
Infrared Imaging : A Motion Detection Circuit for Rattlesnake Thermal Vision
- 2019
-
Ingår i: Current Biology. - : Elsevier BV. - 0960-9822. ; 29:11, s. 403-405
-
Tidskriftsartikel (refereegranskat)abstract
- Pit vipers detect moving warm-blooded prey with infrared receptors in their pit organs. Neurons in two brain nuclei extract the direction of prey motion by lateral inhibition circuits similar to those known from visual systems.
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