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Circadian Entrainment of Drosophila Melanogaster
Published on: June 3, 2020
Persistent diel melatonin rhythmicity during the Arctic summer in free-living willow warblers
Bengt Silverin1, Eberhard Gwinner, Thomas J Van't Hof
1Department of Zoology, University of Gothenburg, Gothenburg, Sweden.
Hormones and Behavior
|April 21, 2009
Summary
Arctic songbirds maintain daily activity patterns despite continuous summer light. Diel melatonin rhythms persist, suggesting a physiological mechanism for circadian system function in extreme environments.
Area of Science:
- Chronobiology
- Animal behavior
- Arctic ecology
Background:
- Arctic environments present unique challenges to circadian systems due to extreme light variations during solstices.
- Songbirds exhibit clear daily activity patterns even when light cues are minimal.
- Melatonin secretion is crucial for circadian regulation in songbirds, and its suppression by constant light can disrupt behavior.
Purpose of the Study:
- To investigate the physiological basis of daily rhythmicity in Arctic songbirds under continuous summer light.
- To examine melatonin secretion patterns in willow warblers (Phylloscopus trochilus) during the Arctic summer.
- To compare melatonin profiles between southern and northern Swedish populations during the summer solstice.
Main Methods:
- Studied free-living migratory willow warblers (Phylloscopus trochilus).
- Compared melatonin profiles in populations at 58 degrees N and 66 degrees N (near Arctic circle).
- Collected data during late spring and summer solstice.
Main Results:
- The northern population (66 degrees N) exhibited clear diel changes in melatonin secretion during the summer solstice.
- Peak melatonin concentrations were lower in the northern population compared to the southern population.
- Melatonin levels peaked before midnight, correlating with reduced activity periods.
Conclusions:
- Diel melatonin rhythmicity is maintained in willow warblers under continuous Arctic summer light.
- This rhythmic melatonin secretion may be a key physiological mechanism enabling circadian system function in the Arctic.
- Songbirds can adapt their circadian regulation to extreme photoperiods.
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