| 1. |
- Baird, Emily, et al.
(författare)
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The neuroecology of bee flight behaviours
- 2020
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Ingår i: Current Opinion in Insect Science. - : Elsevier BV. - 2214-5745 .- 2214-5753. ; 42, s. 8-13
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Tidskriftsartikel (refereegranskat)abstract
- By combining functional, ecological and evolutionary perspectives, neuroecology can provide key insights into understanding how behaviour and the underlying sensory and neural processes are shaped by ecology and evolutionary history. Bees are an ideal system for neuroecological studies because they represent a numerous and diverse insect group that inhabit a broad range of environments. Flight is central to the evolutionary success of bees and is the key to their survival and fitness but this review of recent work on fundamental flight behaviours in different species - landing, collision avoidance and speed control - reveals striking differences. We discuss the potential ecological and evolutionary drivers behind this variation but argue that to understand their adaptive value future work should include multidisciplinary approaches that integrate neuroscience, ecology, phylogeny and behaviour.
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| 2. |
- Bartholomée, Océane, et al.
(författare)
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Shining a light on bumblebee foraging strategies: bumblebee species niche partitioning is related to visual sensory traits
- 2023
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Ingår i: Proceedings of the Royal Society B: Biological Sciences. - 1471-2954. ; 290:1996
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Tidskriftsartikel (refereegranskat)abstract
- Local coexistence of bees has been explained by flower resource partitioning, but coexisting bumblebee species often have strongly overlapping diets. We investigated if light microhabitat niche separation, underpinned by visual traits, could serve as an alternative mechanism underlying local coexistence of bumblebee species. To this end, we focused on a homogeneous flower resource—bilberry—in a heterogeneous light environment—hemi-boreal forests. We found that bumblebee communities segregated along a gradient of light intensity. The community-weighted mean of the eye parameter—a metric measuring the compromise between light sensitivity and visual resolution—decreased with light intensity, showing a higher investment in light sensitivity of communities observed in darker conditions. This pattern was consistent at the species level. In general, species with higher eye parameter (larger investment in light sensitivity) foraged in dimmer light than those with a lower eye parameter (higher investment in visual resolution). Moreover, species realized niche optimum was linearly related to their eye parameter. These results suggest microhabitat niche partitioning to be a potential mechanism underpinning bumblebee species coexistence. This study highlights the importance of considering sensory traits when studying pollinator habitat use and their ability to cope with changing environments.
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| 3. |
- Bartholomée, Océane, et al.
(författare)
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Shining a light on species coexistence : visual traits drive bumblebee communities
- 2023
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - 0962-8452 .- 1471-2954. ; 290:1996
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Tidskriftsartikel (refereegranskat)abstract
- Local coexistence of bees has been explained by flower resource partitioning, but coexisting bumblebee species often have strongly overlapping diets. We investigated if light microhabitat niche separation, underpinned by visual traits, could serve as an alternative mechanism underlying local coexistence of bumblebee species. To this end, we focused on a homogeneous flower resource—bilberry—in a heterogeneous light environment—hemi-boreal forests. We found that bumblebee communities segregated along a gradient of light intensity. The community-weighted mean of the eye parameter—a metric measuring the compromise between light sensitivity and visual resolution—decreased with light intensity, showing a higher investment in light sensitivity of communities observed in darker conditions. This pattern was consistent at the species level. In general, species with higher eye parameter (larger investment in light sensitivity) foraged in dimmer light than those with a lower eye parameter (higher investment in visual resolution). Moreover, species realized niche optimum was linearly related to their eye parameter. These results suggest microhabitat niche partitioning to be a potential mechanism underpinning bumblebee species coexistence. This study highlights the importance of considering sensory traits when studying pollinator habitat use and their ability to cope with changing environments.
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| 4. |
- Jezeera, M. Asmi, et al.
(författare)
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Spatial resolution and sensitivity of the eyes of the stingless bee, Tetragonula iridipennis
- 2022
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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
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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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| 5. |
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| 6. |
- Taylor, Gavin J., et al.
(författare)
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Bumblebee visual allometry results in locally improved resolution and globally improved sensitivity
- 2019
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Ingår i: eLife. - 2050-084X. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- The quality of visual information that is available to an animal is limited by the size of its eyes. Differences in eye size can be observed even between closely related individuals, yet we understand little about how this affects vision. Insects are good models for exploring the effects of size on visual systems because many insect species exhibit size polymorphism. Previous work has been limited by difficulties in determining the 3D structure of eyes. We have developed a novel method based on x-ray microtomography to measure the 3D structure of insect eyes and to calculate predictions of their visual capabilities. We used our method to investigate visual allometry in the bumblebee Bombus terrestris and found that size affects specific aspects of vision, including binocular overlap, optical sensitivity, and dorsofrontal visual resolution. This reveals that differential scaling between eye areas provides flexibility that improves the visual capabilities of larger bumblebees.
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| 7. |
- Tichit, Pierre, et al.
(författare)
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Accelerated landing in a stingless bee and its unexpected benefits for traffic congestion
- 2020
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Ingår i: Royal Society of London. Proceedings B. Biological Sciences. - : The Royal Society. - 1471-2954. ; 287:1921
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Tidskriftsartikel (refereegranskat)abstract
- To land, flying animals must simultaneously reduce speed and control their path to the target. While the control of approach speed has been studied in many different animals, little is known about the effect of target size on landing, particularly for small targets that require precise trajectory control. To begin to explore this, we recorded the stingless bees Scaptotrigona depilis landing on their natural hive entrance-a narrow wax tube built by the bees themselves. Rather than decelerating before touchdown as most animals do, S. depilis accelerates in preparation for its high precision landings on the narrow tube of wax. A simulation of traffic at the hive suggests that this counterintuitive landing strategy could confer a collective advantage to the colony by minimizing the risk of mid-air collisions and thus of traffic congestion. If the simulated size of the hive entrance increases and if traffic intensity decreases relative to the measured real-world values, 'accelerated landing' ceases to provide a clear benefit, suggesting that it is only a useful strategy when target cross-section is small and landing traffic is high. We discuss this strategy in the context of S. depilis' ecology and propose that it is an adaptive behaviour that benefits foraging and nest defence.
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| 8. |
- Tichit, Pierre, et al.
(författare)
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Accelerated landings in stingless bees are triggered by visual threshold cues
- 2020
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Ingår i: Biology Letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 16:8
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Tidskriftsartikel (refereegranskat)abstract
- Most flying animals rely primarily on visual cues to coordinate and control their trajectory when landing. Studies of visually guided landing typically involve animals that decrease their speed before touchdown. Here, we investigate the control strategy of the stingless bee Scaptotrigona depilis, which instead accelerates when landing on its narrow hive entrance. By presenting artificial targets that resemble the entrance at different locations on the hive, we show that these accelerated landings are triggered by visual cues. We also found that S. depilis initiated landing and extended their legs when the angular size of the target reached a given threshold. Regardless of target size, the magnitude of acceleration was the same and the bees aimed for the same relative position on the target suggesting that S. depilis use a computationally simple but elegant ‘stereotyped' landing strategy that requires few visual cues.
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| 9. |
- Tichit, Pierre, et al.
(författare)
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InSegtCone : interactive segmentation of crystalline cones in compound eyes
- 2022
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Ingår i: BMC Zoology. - : Springer Science and Business Media LLC. - 2056-3132. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Understanding the diversity of eyes is crucial to unravel how different animals use vision to interact with their respective environments. To date, comparative studies of eye anatomy are scarce because they often involve time-consuming or inefficient methods. X-ray micro-tomography (micro-CT) is a promising high-throughput imaging technique that enables to reconstruct the 3D anatomy of eyes, but powerful tools are needed to perform fast conversions of anatomical reconstructions into functional eye models. Results: We developed a computing method named InSegtCone to automatically segment the crystalline cones in the apposition compound eyes of arthropods. Here, we describe the full auto-segmentation process, showcase its application to three different insect compound eyes and evaluate its performance. The auto-segmentation could successfully label the full individual shapes of 60-80% of the crystalline cones and is about as accurate and 250 times faster than manual labelling of the individual cones. Conclusions: We believe that InSegtCone can be an important tool for peer scientists to measure the orientation, size and dynamics of crystalline cones, leading to the accurate optical modelling of the diversity of arthropod eyes with micro-CT.
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| 10. |
- Tichit, Pierre
(författare)
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The visual ecology of bees - Tales of diverse eyes and behaviours
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The buzzing flight of bees is a popular summer hit. Yet, outside of a few familiar species of honeybees and bumblebees, these fantastic little creatures are still mostly unknown. With about twenty-five thousand species, bees are a very diverse group. They can be found in drastically different habitats. For example, some kinds of bumblebees endure the freezing temperatures and windswept tundra of Greenland, while others only thrive in the heat and humidity of the Amazonian forest. Some bees live in huge colonies with tens of thousands of members, while others live solitary lives. Some are narrower than a sesame seed, while others can reach the size of a human thumb. Despite these differences, bees all have in common the urge to visit flowers where they find their food. This habit makes them very important for the pollination of plants across the world. To go about their laborious life, bees make extensive use of their vision. They possess two types of eyes – ocelli and compound eyes – that they use to control their flight, find their way through the world, discover flowers and spot possible mates. To understand how bees interact with the environment, we thus need to explore the diversity of their eyes and of how they use them.The first chapter of my thesis is about landing, which is a fundamental behaviour in flying insects. However, in bees it is poorly known whether different species land in different ways. During an expedition to Brazil, I came across a species of bee with the most peculiar landing style. Rather than slowing down to land, as most animals do, these bees accelerate just before touchdown on the entrance to their hive. Why do these bees speed up when they land? Using a computer simulation, I found that this weird strategy may help the bees to avoid mid-air collisions with nestmates and reduce bee ‘traffic jams’ in front of the hive. In turn, this would make food collection more efficient for the colony and it would be easier for hive members to defend against intruders. With this chapter, I showed that the lifestyle of bees – where they live, how many there are and if they are exposed to intruders – can strongly influence their behaviour.In chapter two, I then asked if and how the bees from chapter one use vision to control their peculiar landing. I found that they did indeed rely on vision to control their landing and that they did so in a simple manner. Essentially, when the image of the entrance of the hive reaches a given size on their eyes, these bees start to speed up. When the image of the entrance reaches a second set size on the eyes of landing bees, they extend their landing gear – which is, for bees, their legs – in preparation for touchdown. This chapter reveals that bees can use simple rules to achieve complex behaviours such as landing safely.To explore the diversity of eyes in a large number of bees, we use X-ray images taken from a sample as it rotates (an approach known as computed tomography or CT, commonly used in a medical setting) to produce 3D images of the eyes. However, powerful tools are needed to analyse the large amounts of data that this approach generates. As I want to better understand how bee eyes work, I needed an efficient method for analysing 3D eye images created by CT, so I developed an automatic tool for distinguishing essential optical structures in the eyes of insects and other arthropods. In chapter three, I describe this method, provide a guide to use it, and give examples of its application to a few insect eyes.In the last chapter, I used CT to look into the diversity of the eyes across a range of bumblebees from different habitats around the world. Even though different species are genetically close to each other, I found that their eyes were far from ‘all the same’. For example, bumblebees that live in forests have eyes that may enable them to see less sharp but better in dim light than bumblebees living in open landscapes. I also found that cuckoo bumblebees – bees that lay their eggs in another bumblebee hive like cuckoo birds do – had peculiar eyes in comparison to other bumblebees. This indicates that the eyes of each species of bumblebees may be specialised for a specific combination of lifestyle and habitat. These results are important for the conservation of bumblebees because they suggest that the eyes of some species may make them more sensitive than others to changes in the environment. For example, farming practices that create large open fields may particularly disadvantage bumblebees with eyes adapted to forests.These four chapters only scratch the surface of the tight links between the eyes of bees, the ways they behave, and the worlds they live in. I hope that efforts to look into their diverse eyes will continue and will help to protect these crucial but endangered animals.
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