| 1. |
- Glasbey, JC, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 2. |
- Docherty, Anna R, et al.
(författare)
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GWAS Meta-Analysis of Suicide Attempt: Identification of 12 Genome-Wide Significant Loci and Implication of Genetic Risks for Specific Health Factors.
- 2023
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Ingår i: The American journal of psychiatry. - : American Psychiatric Association Publishing. - 1535-7228 .- 0002-953X. ; 180:10, s. 723-738
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Tidskriftsartikel (refereegranskat)abstract
- Suicidal behavior is heritable and is a major cause of death worldwide. Two large-scale genome-wide association studies (GWASs) recently discovered and cross-validated genome-wide significant (GWS) loci for suicide attempt (SA). The present study leveraged the genetic cohorts from both studies to conduct the largest GWAS meta-analysis of SA to date. Multi-ancestry and admixture-specific meta-analyses were conducted within groups of significant African, East Asian, and European ancestry admixtures.This study comprised 22 cohorts, including 43,871 SA cases and 915,025 ancestry-matched controls. Analytical methods across multi-ancestry and individual ancestry admixtures included inverse variance-weighted fixed-effects meta-analyses, followed by gene, gene-set, tissue-set, and drug-target enrichment, as well as summary-data-based Mendelian randomization with brain expression quantitative trait loci data, phenome-wide genetic correlation, and genetic causal proportion analyses.Multi-ancestry and European ancestry admixture GWAS meta-analyses identified 12 risk loci at p values <5×10-8. These loci were mostly intergenic and implicated DRD2, SLC6A9, FURIN, NLGN1, SOX5, PDE4B, and CACNG2. The multi-ancestry SNP-based heritability estimate of SA was 5.7% on the liability scale (SE=0.003, p=5.7×10-80). Significant brain tissue gene expression and drug set enrichment were observed. There was shared genetic variation of SA with attention deficit hyperactivity disorder, smoking, and risk tolerance after conditioning SA on both major depressive disorder and posttraumatic stress disorder. Genetic causal proportion analyses implicated shared genetic risk for specific health factors.This multi-ancestry analysis of suicide attempt identified several loci contributing to risk and establishes significant shared genetic covariation with clinical phenotypes. These findings provide insight into genetic factors associated with suicide attempt across ancestry admixture populations, in veteran and civilian populations, and in attempt versus death.
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| 3. |
- Mullins, Niamh, et al.
(författare)
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Dissecting the Shared Genetic Architecture of Suicide Attempt, Psychiatric Disorders, and Known Risk Factors
- 2022
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Ingår i: Biological Psychiatry. - : Elsevier. - 0006-3223 .- 1873-2402. ; 91:3, s. 313-327
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Suicide is a leading cause of death worldwide, and nonfatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both have substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders.METHODS: We conducted a genome-wide association study (GWAS) of 29,782 suicide attempt (SA) cases and 519,961 controls in the International Suicide Genetics Consortium (ISGC). The GWAS of SA was conditioned on psychiatric disorders using GWAS summary statistics via multitrait-based conditional and joint analysis, to remove genetic effects on SA mediated by psychiatric disorders. We investigated the shared and divergent genetic architectures of SA, psychiatric disorders, and other known risk factors.RESULTS: Two loci reached genome-wide significance for SA: the major histocompatibility complex and an intergenic locus on chromosome 7, the latter of which remained associated with SA after conditioning on psychiatric disorders and replicated in an independent cohort from the Million Veteran Program. This locus has been implicated in risk-taking behavior, smoking, and insomnia. SA showed strong genetic correlation with psychiatric disorders, particularly major depression, and also with smoking, pain, risk-taking behavior, sleep disturbances, lower educational attainment, reproductive traits, lower socioeconomic status, and poorer general health. After conditioning on psychiatric disorders, the genetic correlations between SA and psychiatric disorders decreased, whereas those with nonpsychiatric traits remained largely unchanged.CONCLUSIONS: Our results identify a risk locus that contributes more strongly to SA than other phenotypes and suggest a shared underlying biology between SA and known risk factors that is not mediated by psychiatric disorders.
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| 4. |
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| 5. |
- Bravo, L, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 6. |
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| 7. |
- Tabiri, S, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 8. |
- Baird, Emily, et al.
(författare)
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Bearing selection in ball-rolling dung beetles: is it constant?
- 2010
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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. ; 196, s. 801-806
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Tidskriftsartikel (refereegranskat)abstract
- Ball rolling in dung beetles is thought to have evolved as a means to escape intense inter- and intra-specific competition at the dung pile. Accordingly, dung beetles typically roll along a straight-line path away from the pile, this being the most effective escape strategy for transporting dung to a suitable burial site. In this study, we investigate how individual diurnal dung beetles, Scarabaeus (Kheper) nigroaeneus, select the compass bearing of their straight-line rolls. In particular, we examine whether roll bearings are constant with respect to geographic cues, celestial cues, or other environmental cues (such as wind direction). Our results reveal that the roll bearings taken by individual beetles are not constant with respect to geographic or celestial references. Environmental cues appear to have some influence over bearing selection, although the relationship is not strong. Furthermore, the variance in roll bearing that we observe is not affected by the presence or absence of other beetles. Thus, rather than being constant for individual beetles, bearing selection varies each time a beetle makes a ball and rolls it away from the dung pile. This strategy allows beetles to make an efficient escape from the dung pile while minimizing the chance of encountering competition.
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| 9. |
- Baird, Emily, et al.
(författare)
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The dung beetle dance: an orientation behaviour?
- 2012
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- An interesting feature of dung beetle behaviour is that once they have formed a piece of dung into a ball, they roll it along a straight path away from the dung pile. This straight-line orientation ensures that the beetles depart along the most direct route, guaranteeing that they will not return to the intense competition (from other beetles) that occurs near the dung pile. Before rolling a new ball away from the dung pile, dung beetles perform a characteristic "dance," in which they climb on top of the ball and rotate about their vertical axis. This dance behaviour can also be observed during the beetles' straight-line departure from the dung pile. The aim of the present study is to investigate the purpose of the dung beetle dance. To do this, we explored the circumstances that elicit dance behaviour in the diurnal ball-rolling dung beetle, Scarabaeus (Kheper) nigroaeneus. Our results reveal that dances are elicited when the beetles lose control of their ball or lose contact with it altogether. We also find that dances can be elicited by both active and passive deviations of course and by changes in visual cues alone. In light of these results, we hypothesise that the dung beetle dance is a visually mediated mechanism that facilitates straight-line orientation in ball-rolling dung beetles by allowing them to 1) establish a roll bearing and 2) return to this chosen bearing after experiencing a disturbance to the roll path.
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| 10. |
- Byrne, Jenny, et al.
(författare)
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Climate change and everyday life : repertoires children use to negotiate a socio-scientific issue
- 2014
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Ingår i: International Journal of Science Education. - Abingdon, Oxon : Taylor & Francis. - 0950-0693 .- 1464-5289. ; 36:9, s. 1491-1509
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Tidskriftsartikel (refereegranskat)abstract
- There are only a few studies about how primary school students engage in socio-scientific discussions. This study aims to add to this field of research by focusing on how 9–10-year-olds in Sweden and England handle climate change as a complex environmental socio-scientific issue (SSI), within the context of their own lives and in relation to society at large. It focuses on how different interpretative repertoires were used by the students in discussions to legitimise or question their everyday lifestyles. They discussed four possible options that a government might consider to help reduce carbon dioxide production. Six main repertoires were identified: Everyday life, Self-Interest, Environment, Science and Technology, Society and Justice. The Everyday life repertoire was used when students related their discussion to their everyday lifestyles. Science and technology-related solutions were offered to maintain or improve things, but these were sometimes rather unrealistic. Arguments related to environment and health frequently appeared to have a superior status compared to the others. Findings also highlighted how conflicts between the students were actually productive by bringing in several perspectives to negotiate the solutions. These primary school students were, therefore, able to discuss and negotiate a complex real-world SSI. Students positioned themselves as active contributors to society, using their life experiences and limited knowledge to understand the problems that affected their everyday lives. Honing these skills within a school science community of practice could facilitate primary students’ engagement with SSIs and empower them as citizens.
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| 11. |
- Byrne, Jenny, et al.
(författare)
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How primary school students in Sweden and England discuss global warming
- 2011
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Ingår i: Science learning and citizenship.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This study identifies and categorizes the discursive repertoires used by 9-10 year old children in Sweden and England during discussions about the socio-scientific issue of global warming. School science is a community of practice where student identities and discourses can be expressed and developed, and the research focuses on how the use of repertoires is related to the identities the students express in their discussions. It explores what repertoires become important in the discussions, which identities the students express, and what differences there are between children’s discussions in Sweden and England. The children discussed four possible options that a government might consider to help reduce global warming. Findings indicate that children in both countries use a range of similar repertoires when discussing global warming. When these repertoires are in conflict with each other, students have to ‘renegotiate’ their own identities. Socio-economic status appears to have an effect on the intensity and depth of argument in the Swedish schools, whereas in the English schools the level and quality of argument seemed to be more closely connected to children’s familiarity with a discursive classroom environment. Young children seem capable of applying a variety of arguments that are logical to them according to the repertoire(s) they employ, but we must encourage changes to pedagogical practice that enable all children to engage in such socio-scientific discussions.
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| 12. |
- Byrne, Sean Anthony, et al.
(författare)
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Precise localization of corneal reflections in eye images using deep learning trained on synthetic data
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Ingår i: Behavior Research Methods. - 1554-3528.
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Tidskriftsartikel (refereegranskat)abstract
- We present a deep learning method for accurately localizing the center of a single corneal reflection (CR) in an eye image. Unlike previous approaches, we use a convolutional neural network (CNN) that was trained solely using synthetic data. Using only synthetic data has the benefit of completely sidestepping the time-consuming process of manual annotation that is required for supervised training on real eye images. To systematically evaluate the accuracy of our method, we first tested it on images with synthetic CRs placed on different backgrounds and embedded in varying levels of noise. Second, we tested the method on two datasets consisting of high-quality videos captured from real eyes. Our method outperformed state-of-the-art algorithmic methods on real eye images with a 3-41.5% reduction in terms of spatial precision across data sets, and performed on par with state-of-the-art on synthetic images in terms of spatial accuracy. We conclude that our method provides a precise method for CR center localization and provides a solution to the data availability problem, which is one of the important common roadblocks in the development of deep learning models for gaze estimation. Due to the superior CR center localization and ease of application, our method has the potential to improve the accuracy and precision of CR-based eye trackers.
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| 13. |
- Dacke, Marie, et al.
(författare)
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A dung beetle that path integrates without the use of landmarks
- 2020
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Ingår i: Animal Cognition. - : Springer Science and Business Media LLC. - 1435-9448 .- 1435-9456. ; 23, s. 1161-1175
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Tidskriftsartikel (refereegranskat)abstract
- Unusual amongst dung beetles,Scarabaeus galenusdigs a burrow that it provisions by making repeated trips to a nearby dung pile. Even more remarkable is that these beetles return home moving backwards, with a pellet of dung between their hind legs. Here, we explore the strategy thatS. galenususes to find its way home. We find that, like many other insects, they use path integration to calculate the direction and distance to their home. If they fail to locate their burrow, the beetles initiate a distinct looping search behaviour that starts with a characteristic sharp turn, we have called a 'turning point'. When homing beetles are passively displaced or transferred to an unfamiliar environment, they initiate a search at a point very close to the location of their fictive burrow-that is, a spot at the same relative distance and direction from the pick-up point as the original burrow. Unlike other insects,S. galenusdo not appear to supplement estimates of the burrow location with landmark information. Thus,S. galenusrepresents a rare case of a consistently backward-homing animal that does not use landmarks to augment its path integration strategy.
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| 14. |
- Dacke, Marie, et al.
(författare)
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Dung beetles ignore landmarks for straight-line orientation
- 2012
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Ingår i: Journal of Comparative Physiology A. - : Springer Science and Business Media LLC. - 1432-1351 .- 0340-7594. ; 199, s. 17-23
-
Tidskriftsartikel (refereegranskat)abstract
- Upon locating a suitable dung pile, ball-rolling dung beetles shape a piece of dung into a ball and roll it away in a straight line. This guarantees that they will not return to the dung pile, where they risk having their ball stolen by other beetles. Dung beetles are known to use celestial compass cues such as the sun, the moon and the pattern of polarised light formed around these light sources to roll their balls of dung along straight paths. Here, we investigate whether terrestrial landmarks have any influence on straight-line orientation in dung beetles. We find that the removal or re-arrangement of landmarks has no effect on the beetle’s orientation precision. Celestial compass cues dominate straight-line orientation in dung beetles so strongly that, under heavily overcast conditions or when prevented from seeing the sky, the beetles can no longer orient along straight paths. To our knowledge, this is the only animal with a visual compass system that ignores the extra orientation precision that landmarks can offer.
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| 15. |
- Dacke, Marie, et al.
(författare)
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Dung Beetles Use the Milky Way for Orientation
- 2013
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Ingår i: Current Biology. - : Elsevier BV. - 1879-0445 .- 0960-9822. ; 23:4, s. 298-300
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Tidskriftsartikel (refereegranskat)abstract
- When the moon is absent from the night sky, stars remain as celestial visual cues. Nonetheless, only birds [1, 2], seals [3], and humans [4] are known to use stars for orientation. African ball-rolling dung beetles exploit the sun, the moon, and the celestial polarization pattern to move along straight paths, away from the intense competition at the dung pile [5-9]. Even on clear moonless nights, many beetles still manage to orientate along straight paths [5]. This led us to hypothesize that dung beetles exploit the starry sky for orientation, a feat that has, to our knowledge, never been demonstrated in an insect. Here, we show that dung beetles transport their dung balls along straight paths under a starlit sky but lose this ability under overcast conditions. In a planetarium, the beetles orientate equally well when rolling under a full starlit sky as when only the Milky Way is present. The use of this bidirectional celestial cue for orientation has been proposed for vertebrates [10], spiders [11], and insects [5, 12], but never proven. This finding represents the first convincing demonstration for the use of the starry sky for orientation in insects and provides the first documented use of the Milky Way for orientation in the animal kingdom.
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| 16. |
- Dacke, Marie, et al.
(författare)
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How Dung Beetles Steer Straight
- 2021
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Ingår i: Annual Review of Entomology. - : Annual Reviews. - 0066-4170 .- 1545-4487. ; 66, s. 243-256
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Tidskriftsartikel (refereegranskat)abstract
- Distant and predictable features in the environment make ideal compass cues to allow movement along a straight path. Ball-rolling dung beetles use a wide range of different signals in the day or night sky to steer themselves along a fixed bearing. These include the sun, the Milky Way, and the polarization pattern generated by the moon. Almost two decades of research into these remarkable creatures have shown that the dung beetle's compass is flexible and readily adapts to the cues available in its current surroundings. In the morning and afternoon, dung beetles use the sun to orient, but at midday, they prefer to use the wind, and at night or in a forest, they rely primarily on polarized skylight to maintain straight paths. We are just starting to understand the neuronal substrate underlying the dung beetle's compass and the mystery of why these beetles start each journey with a dance.
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| 17. |
- Dacke, Marie, et al.
(författare)
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Multimodal cue integration in the dung beetle compass
- 2019
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 116:28, s. 14248-14253
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Tidskriftsartikel (refereegranskat)abstract
- South African ball-rolling dung beetles exhibit a unique orientation behavior to avoid competition for food: after forming a piece of dung into a ball, they efficiently escape with it from the dung pile along a straight-line path. To keep track of their heading, these animals use celestial cues, such as the sun, as an orientation reference. Here we show that wind can also be used as a guiding cue for the ball-rolling beetles. We demonstrate that this mechanosensory compass cue is only used when skylight cues are difficult to read, i.e., when the sun is close to the zenith. This raises the question of how the beetles combine multimodal orientation input to obtain a robust heading estimate. To study this, we performed behavioral experiments in a tightly controlled indoor arena. This revealed that the beetles register directional information provided by the sun and the wind and can use them in a weighted manner. Moreover, the directional information can be transferred between these 2 sensory modalities, suggesting that they are combined in the spatial memory network in the beetle's brain. This flexible use of compass cue preferences relative to the prevailing visual and mechanosensory scenery provides a simple, yet effective, mechanism for enabling precise compass orientation at any time of the day.
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| 18. |
- Dacke, Marie, et al.
(författare)
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The role of the sun in the celestial compass of dung beetles.
- 2014
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Ingår i: Philosophical Transactions of the Royal Society B: Biological Sciences. - : The Royal Society. - 1471-2970 .- 0962-8436. ; 369:1636
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Tidskriftsartikel (refereegranskat)abstract
- Recent research has focused on the different types of compass cues available to ball-rolling beetles for orientation, but little is known about the relative precision of each of these cues and how they interact. In this study, we find that the absolute orientation error of the celestial compass of the day-active dung beetle Scarabaeus lamarcki doubles from 16° at solar elevations below 60° to an error of 29° at solar elevations above 75°. As ball-rolling dung beetles rely solely on celestial compass cues for their orientation, these insects experience a large decrease in orientation precision towards the middle of the day. We also find that in the compass system of dung beetles, the solar cues and the skylight cues are used together and share the control of orientation behaviour. Finally, we demonstrate that the relative influence of the azimuthal position of the sun for straight-line orientation decreases as the sun draws closer to the horizon. In conclusion, ball-rolling dung beetles possess a dynamic celestial compass system in which the orientation precision and the relative influence of the solar compass cues change over the course of the day.
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| 19. |
- El Jundi, Basil, et al.
(författare)
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A snapshot-based mechanism for celestial orientation
- 2016
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Ingår i: Current Biology. - : Elsevier BV. - 0960-9822. ; 26
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Tidskriftsartikel (refereegranskat)abstract
- n order to protect their food from competitors, ball-rolling dung beetles detach a piece of dung from a pile, shape it into a ball, and roll it away along a straight path [1]. They appear to rely exclusively on celestial compass cues to maintain their bearing [2, 3, 4, 5, 6, 7 and 8], but the mechanism that enables them to use these cues for orientation remains unknown. Here, we describe the orientation strategy that allows dung beetles to use celestial cues in a dynamic fashion. We tested the underlying orientation mechanism by presenting beetles with a combination of simulated celestial cues (sun, polarized light, and spectral cues). We show that these animals do not rely on an innate prediction of the natural geographical relationship between celestial cues, as other navigating insects seem to [9 and 10]. Instead, they appear to form an internal representation of the prevailing celestial scene, a “celestial snapshot,” even if that scene represents a physical impossibility for the real sky. We also find that the beetles are able to maintain their bearing with respect to the presented cues only if the cues are visible when the snapshot is taken. This happens during the “dance,” a behavior in which the beetle climbs on top of its ball and rotates about its vertical axis [11]. This strategy for reading celestial signals is a simple but efficient mechanism for straight-line orientation.
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| 20. |
- el Jundi, Basil, et al.
(författare)
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Diurnal dung beetles use the intensity gradient and the polarization pattern of the sky for orientation.
- 2014
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 1477-9145 .- 0022-0949. ; 217:13, s. 2422-2429
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Tidskriftsartikel (refereegranskat)abstract
- To escape competition at the dung pile, a ball-rolling dung beetle forms a piece of dung into a ball and rolls it away. To ensure an their efficient escape from the dung pile, the beetles rely on a celestial compass to move along a straight paths. Here, we analyzed the reliability of different skylight cues for this compass and found that dung beetles rely not only on the sun, but also on the skylight polarization pattern. Moreover, we show the first evidence of an insect using the celestial light intensity gradient for orientation. Using a polarizer, we manipulated skylight so that the polarization pattern appeared to turn by 90°. The beetles then changed their bearing close to the expected 90°. This behavior was abolished if the sun was visible to the beetle, suggesting that polarized light is hierarchically subordinate to the sun. If the sky was depolarized and the sun was invisible, the beetles could still move along straight paths. We therefore analyzed the use of the celestial intensity gradient for orientation. Artificially rotating the intensity pattern by 180° caused beetles to orient in the opposite direction. The intensity cue was also found to be subordinate to the sun, and could play a role in disambiguating the polarization signal, especially at low sun elevations.
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| 21. |
- el Jundi, Basil, et al.
(författare)
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Neural coding underlying the cue preference for celestial orientation
- 2015
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 112:36, s. 11395-11400
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Tidskriftsartikel (refereegranskat)abstract
- Diurnal and nocturnal African dung beetles use celestial cues, such as the sun, the moon, and the polarization pattern, to roll dung balls along straight paths across the savanna. Although nocturnal beetles move in the same manner through the same environment as their diurnal relatives, they do so when light conditions are at least 1 million-fold dimmer. Here, we show, for the first time to our knowledge, that the celestial cue preference differs between nocturnal and diurnal beetles in a manner that reflects their contrasting visual ecologies. We also demonstrate how these cue preferences are reflected in the activity of compass neurons in the brain. At night, polarized skylight is the dominant orientation cue for nocturnal beetles. However, if we coerce them to roll during the day, they instead use a celestial body (the sun) as their primary orientation cue. Diurnal beetles, however, persist in using a celestial body for their compass, day or night. Compass neurons in the central complex of diurnal beetles are tuned only to the sun, whereas the same neurons in the nocturnal species switch exclusively to polarized light at lunar light intensities. Thus, these neurons encode the preferences for particular celestial cues and alter their weighting according to ambient light conditions. This flexible encoding of celestial cue preferences relative to the prevailing visual scenery provides a simple, yet effective, mechanism for enabling visual orientation at any light intensity.
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| 22. |
- el Jundi, Basil, et al.
(författare)
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Spectral information as an orientation cue in dung beetles
- 2015
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Ingår i: Biology letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 11:11
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Tidskriftsartikel (refereegranskat)abstract
- During the day, a non-uniform distribution of long and short wavelength light generates a colour gradient across the sky. This gradient could be used as a compass cue, particularly by animals such as dung beetles that rely primarily on celestial cues for orientation. Here, we tested if dung beetles can use spectral cues for orientation by presenting them with monochromatic (green and UV) light spots in an indoor arena. Beetles kept their original bearing when presented with a single light cue, green or UV, or when presented with both light cues set 180° apart. When either the UV or the green light was turned off after the beetles had set their bearing in the presence of both cues, they were still able to maintain their original bearing to the remaining light. However, if the beetles were presented with two identical green light spots set 180° apart, their ability to maintain their original bearing was impaired. In summary, our data show that ball-rolling beetles could potentially use the celestial chromatic gradient as a reference for orientation.
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| 23. |
- El Jundi, Basil, et al.
(författare)
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The brain behind straight-line orientation in dung beetles
- 2019
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 222
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Forskningsöversikt (refereegranskat)abstract
- For many insects, celestial compass cues play an important role in keeping track of their directional headings. One well-investigated group of celestial orientating insects are the African ball-rolling dung beetles. After finding a dung pile, these insects detach a piece, form it into a ball and roll it away along a straight path while facing backwards. A brain region, termed the central complex, acts as an internal compass that constantly updates the ball-rolling dung beetle about its heading. In this review, we give insights into the compass network behind straight-line orientation in dung beetles and place it in the context of the orientation mechanisms and neural networks of other insects. We find that the neuronal network behind straight-line orientation in dung beetles has strong similarities to the ones described in path-integrating and migrating insects, with the central complex being the key control point for this behavior. We conclude that, despite substantial differences in behavior and navigational challenges, dung beetles encode compass information in a similar way to other insects.
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| 24. |
- Foster, James J., et al.
(författare)
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Light pollution forces a change in dung beetle orientation behavior
- 2021
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Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 31:17, s. 3-3942
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Tidskriftsartikel (refereegranskat)abstract
- Increasing global light pollution1,2 threatens the night-time darkness to which most animals are adapted. Light pollution can have detrimental effects on behavior,3–5 including by disrupting the journeys of migratory birds,5,6 sand hoppers,7–9 and moths.10 This is particularly concerning, since many night-active species rely on compass information in the sky, including the moon,11,12 the skylight polarization pattern,13,14 and the stars,15 to hold their course. Even animals not directly exposed to streetlights and illuminated buildings may still experience indirect light pollution in the form of skyglow,3,4 which can extend far beyond urban areas.1,2 While some recent research used simulated light pollution to estimate how skyglow may affect orientation behavior,7–9 the consequences of authentic light pollution for celestial orientation have so far been neglected. Here, we present the results of behavioral experiments at light-polluted and dark-sky sites paired with photographic measurements of each environment. We find that light pollution obscures natural celestial cues and induces dramatic changes in dung beetle orientation behavior, forcing them to rely on bright earthbound beacons in place of their celestial compass. This change in behavior results in attraction toward artificial lights, thereby increasing inter-individual competition and reducing dispersal efficiency. For the many other species of insect, bird, and mammal that rely on the night sky for orientation and migration, these effects could dramatically hinder their vital night-time journeys.
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| 25. |
- Foster, James J., et al.
(författare)
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Orienting to polarized light at night - matching lunar skylight to performance in a nocturnal beetle
- 2019
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Ingår i: The Journal of experimental biology. - : The Company of Biologists. - 1477-9145 .- 0022-0949. ; 222
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Tidskriftsartikel (refereegranskat)abstract
- For polarized light to inform behaviour, the typical range of degrees of polarization observable in the animal's natural environment must be above the threshold for detection and interpretation. Here, we present the first investigation of the degree of linear polarization threshold for orientation behaviour in a nocturnal species, with specific reference to the range of degrees of polarization measured in the night sky. An effect of lunar phase on the degree of polarization of skylight was found, with smaller illuminated fractions of the moon's surface corresponding to lower degrees of polarization in the night sky. We found that the South African dung beetle Escarabaeus satyrus can orient to polarized light for a range of degrees of polarization similar to that observed in diurnal insects, reaching a lower threshold between 0.04 and 0.32, possibly as low as 0.11. For degrees of polarization lower than 0.23, as measured on a crescent moon night, orientation performance was considerably weaker than that observed for completely linearly polarized stimuli, but was nonetheless stronger than in the absence of polarized light.
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| 26. |
- Foster, James J., et al.
(författare)
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Stellar performance : Mechanisms underlying milky way orientation in dung beetles
- 2017
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Ingår i: Philosophical Transactions of the Royal Society B: Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 372:1717
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Tidskriftsartikel (refereegranskat)abstract
- Nocturnal dung beetles (Scarabaeus satyrus) are currently the only animals that have been demonstrated to use the Milky Way for reliable orientation. In this study, we tested the capacity of S. satyrus to orient under a range of artificial celestial cues, and compared the properties of these cues with images of the Milky Way simulated for a beetle’s visual system. We find that the mechanism that permits accurate stellar orientation under the Milky Way is based on an intensity comparison between different regions of the Milky Way. We determined the beetles’ contrast sensitivity for this task in behavioural experiments in the laboratory, and found that the resulting threshold of 13% is sufficient to detect the contrast between the southern and northern arms of the Milky Way under natural conditions. This mechanism should be effective under extremely dim conditions and on nights when the Milky Way forms a near symmetrical band that crosses the zenith. These findings are discussed in the context of studies of stellar orientation in migratory birds and itinerant seals.
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| 27. |
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| 28. |
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| 29. |
- Khaldy, Lana, et al.
(författare)
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Compass cue integration and its relation to the visual ecology of three tribes of ball-rolling dung beetles
- 2021
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Ingår i: Insects. - : MDPI AG. - 2075-4450. ; 12:6
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Tidskriftsartikel (refereegranskat)abstract
- To guide their characteristic straight-line orientation away from the dung pile, ball-rolling dung beetles steer according to directional information provided by celestial cues, which, among the most relevant are the sun and polarised skylight. Most studies regarding the use of celestial cues and their influence on the orientation system of the diurnal ball-rolling beetle have been performed on beetles of the tribe Scarabaeini living in open habitats. These beetles steer primarily according to the directional information provided by the sun. In contrast, Sisyphus fasciculatus, a species from a different dung-beetle tribe (the Sisyphini) that lives in habitats with closely spaced trees and tall grass, relies predominantly on directional information from the celestial pattern of polarised light. To investigate the influence of visual ecology on the relative weight of these cues, we studied the orientation strategy of three different tribes of dung beetles (Scarabaeini, Sisyphini and Gymnopleurini) living within the same biome, but in different habitat types. We found that species within a tribe share the same orientation strategy, but that this strategy differs across the tribes; Scarabaeini, living in open habitats, attribute the greatest relative weight to the directional information from the sun; Sisyphini, living in closed habitats, mainly relies on directional information from polarised skylight; and Gymnopleurini, also living in open habitats, appear to weight both cues equally. We conclude that, despite exhibiting different body size, eye size and morphology, dung beetles nevertheless manage to solve the challenge of straight-line orientation by weighting visual cues that are particular to the habitat in which they are found. This system is however dynamic, allowing them to operate equally well even in the absence of the cue given the greatest relative weight by the particular species.
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| 30. |
- Khaldy, Lana, et al.
(författare)
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Straight-line orientation in the woodland-living beetle Sisyphus fasciculatus
- 2020
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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 .- 1432-1351. ; 206:3, s. 327-335
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Tidskriftsartikel (refereegranskat)abstract
- To transport their balls of dung along a constant bearing, diurnal savannah-living dung beetles rely primarily on the sun for compass information. However, in more cluttered environments, such as woodlands, this solitary compass cue is frequently hidden from view by surrounding vegetation. In these types of habitats, insects can, instead, rely on surrounding landmarks, the canopy pattern, or wide-field celestial cues, such as polarised skylight, for directional information. Here, we investigate the compass orientation strategy behind straight-line orientation in the diurnal woodland-living beetle Sisyphus fasciculatus. We found that, when manipulating the direction of polarised skylight, Si. fasciculatus responded to this change with a similar change in bearing. However, when the apparent position of the sun was moved, the woodland-living beetle did not change its direction of travel. In contrast, the savannah-living beetle Scarabaeus lamarcki responded to the manipulation of the solar position with a corresponding change in bearing. These results suggest that the dominant compass cue used for straight-line orientation in dung beetles may be determined by the celestial cue that is most prominent in their preferred habitat.
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| 31. |
- Khaldy, Lana, et al.
(författare)
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The effect of step size on straight-line orientation
- 2019
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Ingår i: Journal of the Royal Society, Interface. - : The Royal Society. - 1742-5662 .- 1742-5689. ; 16:157
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Tidskriftsartikel (refereegranskat)abstract
- Moving along a straight path is a surprisingly difficult task. This is because, with each ensuing step, noise is generated in the motor and sensory systems, causing the animal to deviate from its intended route. When relying solely on internal sensory information to correct for this noise, the directional error generated with each stride accumulates, ultimately leading to a curved path. In contrast, external compass cues effectively allow the animal to correct for errors in its bearing. Here, we studied straight-line orientation in two different sized dung beetles. This allowed us to characterize and model the size of the directional error generated with each step, in the absence of external visual compass cues (motor error) as well as in the presence of these cues (compass and motor errors). In addition, we model how dung beetles balance the influence of internal and external orientation cues as they orient along straight paths under the open sky. We conclude that the directional error that unavoidably accumulates as the beetle travels is inversely proportional to the step size of the insect, and that both beetle species weigh the two sources of directional information in a similar fashion.
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| 32. |
- Khaldy, Lana, et al.
(författare)
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The interplay of directional information provided by unpolarised and polarised light in the heading direction network of the diurnal dung beetle Kheper lamarcki
- 2022
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 225:3
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Tidskriftsartikel (refereegranskat)abstract
- The sun is the most prominent source of directional information in the heading direction network of the diurnal, ball-rolling dung beetle Kheper lamarcki. If this celestial body is occluded from the beetle's field of view, the distribution of the relative weight between the directional cues that remain shifts in favour of the celestial pattern of polarised light. In this study, we continue to explore the interplay of the sun and polarisation pattern as directional cues in the heading direction network of K. lamarcki. By systematically altering the intensity and degree of the two cues, we effectively change the relative reliability as they appear to the dung beetle. The response of the beetle to these modifications allows us to closely examine how the weighting relationship of these two sources of directional information is influenced and altered in the heading direction network of the beetle. We conclude that the process by which K. lamarcki relies on directional information is very likely done based on Bayesian reasoning, where directional information conveying the highest certainty at a particular moment is afforded the greatest weight.
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| 33. |
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| 34. |
- Maquiling, Virmarie, et al.
(författare)
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V-ir-Net : A Novel Neural Network for Pupil and Corneal Reflection Detection trained on Simulated Light Distributions
- 2023
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Ingår i: MobileHCI '23 Companion : Proceedings of the 25th International Conference on Mobile Human-Computer Interaction - Proceedings of the 25th International Conference on Mobile Human-Computer Interaction. - 9781450399241 ; , s. 1-7
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Konferensbidrag (refereegranskat)abstract
- Deep learning has shown promise for gaze estimation in Virtual Reality (VR) and other head-mounted applications, but such models are hard to train due to lack of available data. Here we introduce a novel method to train neural networks for gaze estimation using synthetic images that model the light distributions captured in a P-CR setup. We tested our model on a dataset of real eye images from a VR setup, achieving 76% accuracy which is close to the state-of-the-art model which was trained on the dataset itself. The localization error for CRs was 1.56 pixels and 2.02 pixels for the pupil, which is on par with state-of-the-art. Our approach allowed inference on the whole dataset without sacrificing data for model training. Our method provides a cost-efficient and lightweight training alternative, eliminating the need for hand-labeled data. It offers flexible customization, e.g. adapting to different illuminator configurations, with minimal code changes.
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| 35. |
- Mullins, Niamh, et al.
(författare)
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GWAS of Suicide Attempt in Psychiatric Disorders and Association With Major Depression Polygenic Risk Scores
- 2019
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Ingår i: American Journal of Psychiatry. - : American Psychiatric Association Publishing. - 0002-953X .- 1535-7228. ; 176:8, s. 651-660
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Tidskriftsartikel (refereegranskat)abstract
- Objective: More than 90% of people who attempt suicide have a psychiatric diagnosis; however, twin and family studies suggest that the genetic etiology of suicide attempt is partially distinct from that of the psychiatric disorders themselves. The authors present the largest genome-wide association study (GWAS) on suicide attempt, using cohorts of individuals with major depressive disorder, bipolar disorder, and schizophrenia from the Psychiatric Genomics Consortium.Methods: The samples comprised 1,622 suicide attempters and 8,786 nonattempters with major depressive disorder; 3,264 attempters and 5,500 nonattempters with bipolar disorder; and 1,683 attempters and 2,946 nonattempters with schizophrenia. A GWAS on suicide attempt was performed by comparing attempters to nonattempters with each disorder, followed by a meta-analysis across disorders. Polygenic risk scoring was used to investigate the genetic relationship between suicide attempt and the psychiatric disorders.Results: Three genome-wide significant loci for suicide attempt were found: one associated with suicide attempt in major depressive disorder, one associated with suicide attempt in bipolar disorder, and one in the meta-analysis of suicide attempt in mood disorders. These associations were not replicated in independent mood disorder cohorts from the UK Biobank and iPSYCH. No significant associations were found in the meta-analysis of all three disorders. Polygenic risk scores for major depression were significantly associated with suicide attempt in major depressive disorder (R2=0.25%), bipolar disorder (R2=0.24%), and schizophrenia (R2=0.40%).Conclusions: This study provides new information on genetic associations and demonstrates that genetic liability for major depression increases risk for suicide attempt across psychiatric disorders. Further collaborative efforts to increase sample size may help to robustly identify genetic associations and provide biological insights into the etiology of suicide attempt.
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| 36. |
- Smolka, Jochen, et al.
(författare)
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A new galloping gait in an insect
- 2013
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Ingår i: Current Biology. - : Elsevier BV. - 1879-0445 .- 0960-9822. ; 23:20, s. 913-915
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Tidskriftsartikel (refereegranskat)abstract
- An estimated three million insect species all walk using variations of the alternating tripod gait. At any one time, these animals hold one stable triangle of legs steady while swinging the opposite triangle forward. Here, we report the discovery that three different flightless desert dung beetles use an additional gallop-like gait, which has never been described in any insect before. Like a bounding hare, the beetles propel their body forward by synchronously stepping with both middle legs and then both front legs. Surprisingly, this peculiar galloping gait delivers lower speeds than the alternating tripod gait. Why these beetles have shifted so radically away from the most widely used walking style on our planet is as yet unknown.
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| 37. |
- Smolka, Jochen, et al.
(författare)
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Dung beetles use their dung ball as a mobile thermal refuge
- 2012
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Ingår i: Current Biology. - : Elsevier BV. - 1879-0445 .- 0960-9822. ; 22:20, s. 863-864
-
Tidskriftsartikel (refereegranskat)abstract
- At midday, surface temperatures in the desert often exceed 60°C. To be active at this time, animals need extraordinary behavioural or physiological adaptations. Desert ants, for instance, spend up to 75% of their foraging time cooling down on elevated thermal refuges such as grass stalks [1]. Ball-rolling dung beetles work under similar thermal conditions in South African savannahs. After landing at a fresh dung pile, a beetle quickly forms a dung ball and rolls it away in a straight line, head down, walking backwards [2]. Earlier studies have shown that some dung beetles maintain an elevated body temperature to gain a competitive advantage [3], [4] and [5], and that heat shunting may prevent overheating during flight [6] and [7]. However, we know little about the behavioural strategies beetles might employ to mitigate heat stress while rolling their dung balls. Using infrared thermography and behavioural experiments, we show here that dung beetles use their dung ball as a mobile thermal refuge onto which they climb to cool down while rolling across hot soil. We further demonstrate that the moist ball functions not only as a portable platform, but also as a heat sink, which effectively cools the beetle as it rolls or climbs onto it.
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| 38. |
- Smolka, Jochen, et al.
(författare)
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Night sky orientation with diurnal and nocturnal eyes: dim-light adaptations are critical when the moon is out of sight
- 2016
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Ingår i: Animal Behaviour. - : Elsevier BV. - 1095-8282 .- 0003-3472. ; 111, s. 127-146
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Tidskriftsartikel (refereegranskat)abstract
- The visual systems of many animals feature energetically costly specializations to enable them to function in dim light. It is often unclear, however, how large the behavioural benefit of these specializations is, because a direct comparison in a behaviourally relevant task between closely related day- and night-active species is not usually possible. Here we compared the orientation performance of diurnal and nocturnal species of dung beetles, Scarabaeus (Kheper) lamarcki and Scarabaeus satyrus, respectively, attempting to roll dung balls along straight paths both during the day and at night. Using video tracking, we quantified the straightness of paths and the repeatability of roll bearings as beetles exited a flat arena in their natural habitat or under controlled conditions indoors. Both species oriented equally well when either the moon or an artificial point light source was available, but when the view of the moon was blocked and only wide-field cues such as the lunar polarization pattern or the stars were available for orientation, nocturnal beetles were oriented substantially better. We found no evidence that ball-rolling speed changed with light level, which suggests little or no temporal summation in the visual system. Finally, we found that both diurnal and nocturnal beetles tended to choose bearings that led them towards a bright light source, but away from a dim one. Our results show that even diurnal insects, at least those with superposition eyes, could orient by the light of the moon, but that dim-light adaptations are needed for precise orientation when the moon is not visible.
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| 39. |
- Tocco, Claudia, et al.
(författare)
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Eye and wing structure closely reflects the visual ecology of dung beetles
- 2019
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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. ; 205:2, s. 211-221
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Tidskriftsartikel (refereegranskat)abstract
- An important resource partitioning strategy allowing dung beetles to coexist in the same habitat, while utilising the same food, is species’ separation of activity times. After establishing the diel activity period of three closely related, co-occurring dung beetles, we examined their eye and wing morphology. Absolute and relative eye size, and facet size were greater in the nocturnal Escarabaeus satyrus, followed by the crepuscular Scarabaeus zambesianus and then the diurnal Kheper lamarcki. The diurnal K. lamarcki had the highest wing aspect ratio (long, narrow wings), followed by the crepuscular S. zambesianus and the nocturnal E. satyrus (short, broad wings), suggesting that dim-light active species fly slower than diurnal species. In addition, the two species active in dim light had a lower wing loading than the diurnal species, indicating the need for greater manoeuvrability in the dark. Analyses of wing shape revealed that the diurnal K. lamarcki wing had a proportionally larger jugal and anal region than both dim light species. Our results show that different species of dung beetles have a combination of optical and morphological wing adaptations to support their foraging activities in diverse light conditions.
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| 40. |
- Tocco, Claudia, et al.
(författare)
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Spider dung beetles : Coordinated cooperative transport without a predefined destination
- 2024
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Ingår i: Proceedings of the Royal Society B: Biological Sciences. - 0962-8452. ; 291:2015
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Tidskriftsartikel (refereegranskat)abstract
- Cooperative transport allows for the transportation of items too large for the capacity of a single individual. Beyond humans, it is regularly employed by ants and social spiders where two or more individuals, with more or less coordinated movements, transport food to a known destination. In contrast to this, pairs of male and female dung beetles successfully transport brood balls to a location unknown to either party at the start of their common journey. We found that, when forced to overcome a series of obstacles in their path, transport efficiency of pairs of beetles was higher than of solo males. To climb tall obstacles with their common ball of dung, the female assisted the leading male in lifting the ball by steadying and pushing it upwards in a 'headstand' position during the climb initiation. Finally, we show that pairs were faster than single beetles in climbing obstacles of different heights. Our results suggest that pairs of Sisyphus beetles cooperate in the transportation of brood balls with coordinated movements, where the male steers and the female primarily assists in lifting the ball. Taken together, this is to our knowledge, the first quantitative study of cooperative food transport without a known goal to aim for.
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| 41. |
- Tocco, Claudia, et al.
(författare)
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The finely defined shift work schedule of dung beetles and their eye morphology
- 2021
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 11:22, s. 15947-15960
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Tidskriftsartikel (refereegranskat)abstract
- In nature, nothing is wasted, not even waste. Dung, composed of metabolic trash and leftovers of food, is a high-quality resource and the object of fierce competition. Over 800 dung beetle species (Scarabaeinae) compete in the South African dung habitat and more than 100 species can colonize a single dung pat. To coexist in the same space, using the same food, beetles divide the day between them. However, detailed diel activity periods and associated morphological adaptations have been largely overlooked in these dung-loving insects. To address this, we used a high-frequency trapping design to establish the diel activity period of 44 dung beetle species in their South Africa communities. This allowed us to conclude that the dung beetles show a highly refined temporal partitioning strategy, with differences in peak of activity even within the diurnal, crepuscular, and nocturnal guilds, independent of nesting behavior and taxonomic classification. We further analyzed differences in eye and body size of our 44 model species and describe their variability in external eye morphology. In general, nocturnal species are bigger than crepuscular and diurnal species, and as expected, the absolute and relative eye size is greatest in nocturnal species, followed by crepuscular and then diurnal species. A more surprising finding was that corneal structure (smooth or facetted) is influenced by the activity period of the species, appearing flat in the nocturnal species and highly curved in the diurnal species. The role of the canthus—a cuticular structure that partially or completely divides the dung beetle eye into dorsal and ventral parts—remains a mystery, but the large number of species investigated in this study nevertheless allowed us to reject any correlation between its presence and the nesting behavior or time of activity of the beetles.
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| 42. |
- Yilmaz, Ayse, et al.
(författare)
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Cold-induced anesthesia impairs path integration memory in dung beetles
- 2022
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Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 32:2, s. 3-444
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Tidskriftsartikel (refereegranskat)abstract
- Path integration is a general mechanism used by many animals to maintain an updated record of their position in relation to a set reference point.1–11 To do this, they continually integrate direction and distance information into a memorized home vector. What remains unclear is how this vector is stored, maintained, and utilized for successful navigation. A recent computational model based on the neuronal circuitry of the insect central complex suggests that home vector memories are encoded across a set of putative memory neurons and maintained through ongoing recurrent neural activity.12 To better understand the nature of the home vector memory and experimentally assess underlying mechanisms for maintaining it, we performed a series of experiments on the path integrating dung beetle Scarabaeus galenus.13 We found that, while the directional component of the home vector was maintained for up to 1 h, the distance component of the vector memory decreased gradually over time. Using cold-induced anesthesia, we disrupted the neural activity of beetles that had stored a home vector of known length and direction. This treatment diminished both components of the home vector memory, but by different amounts—the homing beetles lost their distance memory before their directional memory. Together, these findings present new insights into the functional properties of home vector memories and provide the first empirical evidence that a biological process that can be disrupted by cold-induced anesthesia is essential to support homing by path integration.
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| 43. |
- Yilmaz, Ayse, et al.
(författare)
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Mechanisms of spectral orientation in a diurnal dung beetle
- 2022
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Ingår i: Philosophical Transactions of the Royal Society of London. Biological Sciences. - : Royal Society Publishing. - 0962-8436 .- 1471-2970. ; 377:1862
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Tidskriftsartikel (refereegranskat)abstract
- Ball rolling dung beetles use a wide range of cues to steer themselves along a fixed bearing, including the spectral gradient of scattered skylight that spans the sky. Here, we define the spectral sensitivity of the diurnal dung beetle Kheper lamarcki and use the information to explore the orientation performance under a range of spectral light combinations. We find that, when presented with spectrally diverse stimuli, the beetles primarily orient to the apparent brightness differences as perceived by their green photoreceptors. Under certain wavelength combinations, they also rely on spectral information to guide their movements, but the brightness and spectral directional information is never fully disentangled. Overall, our results suggest the use of a dichromatic, primitive colour vision system for the extraction of directional information from the celestial spectral gradient to support straight-line orientation.
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| 44. |
- Yilmaz, Ayse, et al.
(författare)
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The balbyter ant Camponotus fulvopilosus combines several navigational strategies to support homing when foraging in the close vicinity of its nest
- 2022
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Ingår i: Frontiers in Integrative Neuroscience. - : Frontiers Media SA. - 1662-5145. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- Many insects rely on path integration to define direct routes back to their nests. When shuttling hundreds of meters back and forth between a profitable foraging site and a nest, navigational errors accumulate unavoidably in this compass- and odometer-based system. In familiar terrain, terrestrial landmarks can be used to compensate for these errors and safely guide the insect back to its nest with pin-point precision. In this study, we investigated the homing strategies employed by Camponotus fulvopilosus ants when repeatedly foraging no more than 1.25 m away from their nest. Our results reveal that the return journeys of the ants, even when setting out from a feeder from which the ants could easily get home using landmark information alone, are initially guided by path integration. After a short run in the direction given by the home vector, the ants then switched strategies and started to steer according to the landmarks surrounding their nest. We conclude that even when foraging in the close vicinity of its nest, an ant still benefits from its path-integrated vector to direct the start of its return journey.
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| 45. |
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