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Author  |
Dacke, M.; Baird, E.; Byrne, M.; Scholtz, C.H.; Warrant, E.J. |
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Title |
Dung beetles use the Milky Way for orientation |
Type |
Journal Article |
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Year |
2013 |
Publication |
Current Biology : CB |
Abbreviated Journal |
Curr Biol |
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Volume |
23 |
Issue |
4 |
Pages |
298-300 |
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Keywords |
Animals; Beetles/*physiology; *Behavior, Animal; Cues; Feces; *Galaxies; Locomotion; Moon; Motor Activity; Orientation/*physiology; *Stars, Celestial; Vision, Ocular/physiology; Milky Way; insects |
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Abstract |
When the moon is absent from the night sky, stars remain as celestial visual cues. Nonetheless, only birds, seals, and humans 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. Even on clear moonless nights, many beetles still manage to orientate along straight paths. 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, spiders, and insects, 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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Address |
Department of Biology, Lund University, 223 62 Lund, Sweden. marie.dacke@biol.lu.se |
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English |
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ISSN |
0960-9822 |
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PMID:23352694 |
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Call Number |
IDA @ john @ |
Serial |
116 |
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Author |
Dacke, M.; Byrne, M.J.; Baird, E.; Scholtz, C.H.; Warrant, E.J. |
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Title |
How dim is dim? Precision of the celestial compass in moonlight and sunlight |
Type |
Journal Article |
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Year |
2011 |
Publication |
Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences |
Abbreviated Journal |
Philos Trans R Soc Lond B Biol Sci |
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Volume |
366 |
Issue |
1565 |
Pages |
697-702 |
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Keywords |
Animals; Beetles/*physiology; Behavior, Animal; *Moon; *Sunlight; Video Recording |
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Abstract |
Prominent in the sky, but not visible to humans, is a pattern of polarized skylight formed around both the Sun and the Moon. Dung beetles are, at present, the only animal group known to use the much dimmer polarization pattern formed around the Moon as a compass cue for maintaining travel direction. However, the Moon is not visible every night and the intensity of the celestial polarization pattern gradually declines as the Moon wanes. Therefore, for nocturnal orientation on all moonlit nights, the absolute sensitivity of the dung beetle's polarization detector may limit the precision of this behaviour. To test this, we studied the straight-line foraging behaviour of the nocturnal ball-rolling dung beetle Scarabaeus satyrus to establish when the Moon is too dim--and the polarization pattern too weak--to provide a reliable cue for orientation. Our results show that celestial orientation is as accurate during crescent Moon as it is during full Moon. Moreover, this orientation accuracy is equal to that measured for diurnal species that orient under the 100 million times brighter polarization pattern formed around the Sun. This indicates that, in nocturnal species, the sensitivity of the optical polarization compass can be greatly increased without any loss of precision. |
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Address |
Department of Biology, University of Lund, Helgonavagen 3, 223 62 Lund, Sweden. marie.dacke@cob.lu.se |
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0962-8436 |
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PMID:21282173; PMCID:PMC3049003 |
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no |
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Call Number |
IDA @ john @ |
Serial |
34 |
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Author |
Dacke, M.; Nilsson, D.-E.; Scholtz, C.H.; Byrne, M.; Warrant, E.J. |
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Title |
Animal behaviour: insect orientation to polarized moonlight |
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Journal Article |
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Year |
2003 |
Publication |
Nature |
Abbreviated Journal |
Nature |
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Volume |
424 |
Issue |
6944 |
Pages |
33 |
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Keywords |
Adaptation, Physiological/physiology; Animals; Beetles/*physiology; Feces; Feeding Behavior/physiology; *Light; Locomotion/*physiology; *Moon; Orientation/*physiology; Scarabaeus zambesianus |
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Abstract |
Moonlight, like sunlight, scatters when it strikes tiny particles in the atmosphere, giving rise to celestial polarization patterns. Here we show that an African dung beetle, Scarabaeus zambesianus, uses the polarization of a moonlit sky to orientate itself so that it can move along a straight line. Many creatures use the Sun's light-polarization pattern to orientate themselves, but S. zambesianus is the first animal known to use the million-times dimmer polarization of moonlight for this purpose. |
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Address |
Department of Cell and Organism Biology, University of Lund, 223 62 Lund, Sweden. marie.dacke@cob.lu.se |
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English |
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ISSN |
0028-0836 |
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Notes |
PMID:12840748 |
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no |
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Call Number |
IDA @ john @ |
Serial |
242 |
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Author |
El Jundi, B.; Warrant, E.J.; Byrne, M.J.; Khaldy, L.; Baird, E.; Smolka, J.; Dacke, M. |
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Title |
Neural coding underlying the cue preference for celestial orientation |
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Journal Article |
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Year |
2015 |
Publication |
Proceedings of the National Academy of Sciences of the United States of America |
Abbreviated Journal |
Proc Natl Acad Sci U S A |
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Volume |
112 |
Issue |
36 |
Pages |
11395-11400 |
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Keywords |
animals; vision |
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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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Address |
Department of Biology, Lund University, 223 62 Lund, Sweden; School of Animal, Plant, and Environmental Sciences, University of the Witwatersrand, Wits 2050, South Africa |
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English |
Summary Language |
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ISSN |
0027-8424 |
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Notes |
PMID:26305929 |
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Call Number |
LoNNe @ kyba @ |
Serial |
1263 |
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Author |
Foster, J.J.; Kirwan, J.D.; El Jundi, B.; Smolka, J.; Khaldy, L.; Baird, E.; Byrne, M.J.; Nilsson, D.-E.; Johnsen, S.; Dacke, M. |
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Title |
Orienting to polarized light at night – matching lunar skylight to performance in a nocturnal beetle |
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Journal Article |
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Year |
2019 |
Publication |
The Journal of Experimental Biology |
Abbreviated Journal |
J Exp Biol |
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Volume |
222 |
Issue |
Pt 2 |
Pages |
jeb188532 |
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Keywords |
Animals; Natural skylight; insects; South African dung beetle; Escarabaeus satyrus; polarized light; Orientation |
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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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Address |
Lund Vision Group, Department of Biology, Lund University, Solvegatan 35, 223 62 Lund, Sweden |
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English |
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ISSN |
0022-0949 |
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Notes |
PMID:30530838 |
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no |
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Call Number |
GFZ @ kyba @ |
Serial |
2599 |
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Author |
Foster, J.J.; Smolka, J.; Nilsson, D.-E.; Dacke, M. |
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Title |
How animals follow the stars |
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Journal Article |
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Year |
2018 |
Publication |
Proceedings. Biological Sciences |
Abbreviated Journal |
Proc Biol Sci |
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Volume |
285 |
Issue |
1871 |
Pages |
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Keywords |
Vision; Animals |
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Abstract |
Throughout history, the stars have provided humans with ever more information about our world, enabling increasingly accurate systems of navigation in addition to fuelling some of the greatest scientific controversies. What information animals have evolved to extract from a starry sky and how they do so, is a topic of study that combines the practical and theoretical challenges faced by both astronomers and field biologists. While a number of animal species have been demonstrated to use the stars as a source of directional information, the strategies that these animals use to convert this complex and variable pattern of dim-light points into a reliable 'stellar orientation' cue have been more difficult to ascertain. In this review, we assess the stars as a visual stimulus that conveys directional information, and compare the bodies of evidence available for the different stellar orientation strategies proposed to date. In this context, we also introduce new technologies that may aid in the study of stellar orientation, and suggest how field experiments may be used to characterize the mechanisms underlying stellar orientation. |
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Department of Biology, Lund University, Solvegatan 35, Lund 223 62, Sweden |
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English |
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0962-8452 |
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Notes |
PMID:29367394 |
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no |
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Call Number |
LoNNe @ kyba @ |
Serial |
1802 |
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Author |
Smolka, J.; Baird, E.; el Jundi, B.; Reber, T.; Byrne, M.J.; Dacke, M. |
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Title |
Night sky orientation with diurnal and nocturnal eyes: dim-light adaptations are critical when the moon is out of sight |
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Journal Article |
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Year |
2016 |
Publication |
Animal Behaviour |
Abbreviated Journal |
Animal Behaviour |
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Volume |
111 |
Issue |
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Pages |
127-146 |
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Keywords |
Animals; dung beetle; insect; Milky Way; nocturnal adaptation; polarized moonlight; sky compass; straight-line orientation; vision; Scarabaeus; Scarabaeus lamarcki; Scarabaeus satyrus |
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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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Address |
Department of Biology, Lund University, Biology Building, Sölvegatan 35, 223 62 Lund, Sweden; jochen.smolka(at)biol.lu.se |
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Publisher |
Elsevier |
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English |
Summary Language |
English |
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ISSN |
0003-3472 |
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Call Number |
IDA @ john @ |
Serial |
1317 |
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Author |
Warrant, E.; Dacke, M. |
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Title |
Visual Navigation in Nocturnal Insects |
Type |
Journal Article |
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Year |
2016 |
Publication |
Physiology (Bethesda, Md.) |
Abbreviated Journal |
Physiology (Bethesda) |
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Volume |
31 |
Issue |
3 |
Pages |
182-192 |
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Keywords |
Vision; Animals |
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Abstract |
Despite their tiny eyes and brains, nocturnal insects have evolved a remarkable capacity to visually navigate at night. Whereas some use moonlight or the stars as celestial compass cues to maintain a straight-line course, others use visual landmarks to navigate to and from their nest. These impressive abilities rely on highly sensitive compound eyes and specialized visual processing strategies in the brain. |
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Address |
Department of Biology, Lund Vision Group, University of Lund, Lund, Sweden |
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English |
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1548-9221 |
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PMID:27053732 |
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Call Number |
LoNNe @ kyba @ |
Serial |
1417 |
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