Light-dependent magnetoreception in birds : increasing intensity of monochromatic light changes the nature of the response

Background The Radical Pair model proposes that magnetoreception is a light-dependent process. Under low monochromatic light from the short-wavelength part of the visual spectrum, migratory birds show orientation in thei
Background The Radical Pair model proposes that magnetoreception is a light-dependent process. Under low monochromatic light from the short-wavelength part of the visual spectrum, migratory birds show orientation in their migratory direction. Under monochromatic light of higher intensity, however, they showed unusual preferences in other directions or axial preferences. To determine whether or not these responses are still controlled by the respective light regimes, European robins, Erithacus rubecula, were tested under UV, Blue, Turquoise and Green light at increasing intensities, with orientation in migratory direction serving as a criterion whether or not magnetoreception works in the normal way. Results Under low light with a quantal flux of 8 times 10 to 15 power quanta s-1 m-2, the birds were well oriented in their seasonally appropriate migratory direction under 424 nm Blue, 502 nm Turquoise and 565 nm Green light, indicating unimpaired magnetoreception. Under 373 nm UV of the same quantal flux, they were not oriented in migratory direction, showing a preference of the east-west axis instead, but they showed excellent orientation in migratory direction under UV of lower intensity. Intensities of above 36 times 10 to 15 power quanta s-1 m-2 of Blue, Turquoise and Green light elicited a variety of responses: disorientation, headings along the east-west axis, headings along the north-south axis or 'fixed' direction tendencies. These responses changed as the intensity was increased from 36 times 10 to the 15 power quanta s-1 m-2 to 54 and 72 times 10 to 15 power quanta s-1 m-2. Conclusion The specific manifestation of responses in directions other than migratory direction clearly depends on the ambient light regime. This implies that although mechanisms normally providing magnetic compass information seem disrupted, processes that are activated by light still control the behavior. It suggests complex interactions between different types of receptors, magnetic and visual. The nature of the receptors involved and details of their connections are not yet known; however, a role of the color cones in the processes mediating magnetic input is suggested.
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Metadaten
Author:Roswitha Wiltschko, Katrin Stapput, Hans-Joachim Bischof, Wolfgang Wiltschko
URN:urn:nbn:de:hebis:30-37496
Document Type:Article
Language:English
Date of Publication (online):2007/03/16
Year of first Publication:2007
Publishing Institution:Univ.-Bibliothek Frankfurt am Main
Release Date:2007/03/16
Note:
© 2007 Wiltschko et al., licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Source:Frontiers in Zoology 2007, 4:5 ; http://www.frontiersinzoology.com/content/4/1/5
HeBIS PPN:190992646
Institutes:Biowissenschaften
Dewey Decimal Classification:590 Tiere (Zoologie)
Sammlungen:Universitätspublikationen
Sondersammelgebiets-Volltexte
Licence (German):License LogoCreative Commons - Namensnennung 2.0

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