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Author Warrant, E.
Title Vision in the dimmest habitats on earth Type Journal Article
Year 2004 Publication Journal of Comparative Physiology. A, Neuroethology, Sensory, Neural, and Behavioral Physiology Abbreviated Journal J Comp Physiol A Neuroethol Sens Neural Behav Physiol
Volume 190 Issue 10 Pages 765-789
Keywords Animals; Circadian Rhythm/physiology; *Darkness; Eye/anatomy & histology; Fishes/physiology; Invertebrates; Oceans and Seas; Ocular Physiological Phenomena; Orientation/physiology; Space Perception/physiology; Vision, Ocular/*physiology
Abstract A very large proportion of the world's animal species are active in dim light, either under the cover of night or in the depths of the sea. The worlds they see can be dim and extended, with light reaching the eyes from all directions at once, or they can be composed of bright point sources, like the multitudes of stars seen in a clear night sky or the rare sparks of bioluminescence that are visible in the deep sea. The eye designs of nocturnal and deep-sea animals have evolved in response to these two very different types of habitats, being optimised for maximum sensitivity to extended scenes, or to point sources, or to both. After describing the many visual adaptations that have evolved across the animal kingdom for maximising sensitivity to extended and point-source scenes, I then use case studies from the recent literature to show how these adaptations have endowed nocturnal animals with excellent vision. Nocturnal animals can see colour and negotiate dimly illuminated obstacles during flight. They can also navigate using learned terrestrial landmarks, the constellations of stars or the dim pattern of polarised light formed around the moon. The conclusion from these studies is clear: nocturnal habitats are just as rich in visual details as diurnal habitats are, and nocturnal animals have evolved visual systems capable of exploiting them. The same is certainly true of deep-sea animals, as future research will no doubt reveal.
Address Vision Group, Department of Cell and Organism Biology, University of Lund, Helgonavagen 3, 22362 Lund, Sweden. Eric.Warrant@cob.lu.se
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Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume (down) Series Issue Edition
ISSN 0340-7594 ISBN Medium
Area Expedition Conference
Notes PMID:15375626 Approved no
Call Number IDA @ john @ Serial 33
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Author Dacke, M.; Byrne, M.J.; Baird, E.; Scholtz, C.H.; Warrant, E.J.
Title How dim is dim? Precision of the celestial compass in moonlight and sunlight Type Journal Article
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
Volume 366 Issue 1565 Pages 697-702
Keywords Animals; Beetles/*physiology; Behavior, Animal; *Moon; *Sunlight; Video Recording
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.
Address Department of Biology, University of Lund, Helgonavagen 3, 223 62 Lund, Sweden. marie.dacke@cob.lu.se
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Language English Summary Language Original Title
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Series Volume (down) Series Issue Edition
ISSN 0962-8436 ISBN Medium
Area Expedition Conference
Notes PMID:21282173; PMCID:PMC3049003 Approved no
Call Number IDA @ john @ Serial 34
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Author Kyba, C.C.M.; Hölker, F.
Title Do artificially illuminated skies affect biodiversity in nocturnal landscapes? Type Journal Article
Year 2013 Publication Landscape Ecology Abbreviated Journal Landscape Ecol
Volume 28 Issue 9 Pages 1637-1640
Keywords skyglow; light pollution; biodiversity
Abstract The skyglow from cities at night is one of the most dramatic modifications that humans have made to Earth’s biosphere, and it is increasingly extending into nocturnal landscapes (nightscapes) far beyond urban areas. This scattered light is dim and homogenous compared to a lit street, but can be bright compared to natural celestial light sources, such as stars. Because of the large area of Earth affected by artificial skyglow, it is essential to verify whether skyglow is a selective pressure in nocturnal landscapes. We propose two scientific approaches that could examine whether skyglow affects biodiversity.
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Language Summary Language Original Title
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Series Volume (down) Series Issue Edition
ISSN 0921-2973 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 35
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Author Hölker, F.; Wolter, C.; Perkin, E.K.; Tockner, K.
Title Light pollution as a biodiversity threat Type Journal Article
Year 2010 Publication Trends in Ecology & Evolution Abbreviated Journal Trends Ecol Evol
Volume 25 Issue 12 Pages 681-682
Keywords *Biodiversity; Biological Clocks; Biological Evolution; Ecosystem; *Environmental Monitoring; *Environmental Pollutants; Light/*adverse effects
Abstract
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Language English Summary Language Original Title
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ISSN 0169-5347 ISBN Medium
Area Expedition Conference
Notes PMID:21035893 Approved no
Call Number IDA @ john @ Serial 36
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Author Schoech, S.J.; Bowman, R.; Hahn, T.P.; Goymann, W.; Schwabl, I.; Bridge, E.S.
Title The effects of low levels of light at night upon the endocrine physiology of western scrub-jays (Aphelocoma californica) Type Journal Article
Year 2013 Publication Journal of Experimental Zoology. Part A, Ecological Genetics and Physiology Abbreviated Journal J Exp Zool A Ecol Genet Physiol
Volume 319 Issue 9 Pages 527-538
Keywords Animals; Corticosterone/blood; Ecosystem; Female; *Light; Male; Melatonin/blood; Passeriformes/*physiology; *Photoperiod; Reproduction/*physiology; Testosterone/blood
Abstract Florida scrub-jays (Aphelocoma coerulescens) in the suburbs breed earlier than jays in native habitat. Amongst the possible factors that influence this advance (e.g., food availability, microclimate, predator regime, etc.), is exposure to artificial lights at night (LAN). LAN could stimulate the reproductive axis of the suburban jays. Alternatively, LAN could inhibit pineal melatonin (MEL), thus removing its inhibitory influence on the reproductive axis. Because Florida scrub-jays are a threatened species, we used western scrub-jays (Aphelocoma californica) to investigate the effects of LAN upon reproductive hormones and melatonin. Jays were held under conditions in which the dark-phase of the light:dark cycle was without illumination and then under low levels of LAN. Under both conditions, birds were exposed first to short-days (9.5L:14.5D) that were gradually increased to long-days (14.5L:9.5D). At various times, blood samples were collected during the light part of the cycle to measure reproductive hormones (luteinizing hormone, LH; testosterone, T; and estradiol, E2 ). Similarly, samples to assess melatonin were collected during the dark. In males, LAN caused a depression in LH levels and levels were approximately 4x greater under long- than short-days. In females, there was no effect of LAN or photoperiod upon LH. LAN resulted in depressed T levels in females, although there was no effect on T in males. E2 levels in both sexes were lower under LAN than under an unlighted dark-phase. Paradoxically, MEL was higher in jays under LAN, and under long-days. MEL did not differ by sex. LAN disrupted the extraordinarily strong correlation between T and E2 that existed under unlighted nocturnal conditions. Overall, our findings fail to support the hypothesis that LAN stimulates the reproductive axis. Rather, the data demonstrate that LAN tends to inhibit reproductive hormone secretion, although not in a consistent fashion between the sexes.
Address Department of Biological Sciences, University of Memphis, Memphis, Tennessee
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Language English Summary Language Original Title
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ISSN 1932-5223 ISBN Medium
Area Expedition Conference
Notes PMID:23970442 Approved no
Call Number IDA @ john @ Serial 37
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