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A link between eumelanism and calcium physiology in the barn owl
Alexandre Roulin1, Tom Dauwe, Ronny Blust
1Department of Ecology and Evolution, University of Lausanne, Biology Building, 1015 Lausanne, Switzerland. Alexandre.Roulin@unil.ch
Die Naturwissenschaften
|June 27, 2006
Summary
Melanin coloration in barn owls is linked to calcium. Heavily spotted owls have higher bone calcium, suggesting plumage color reflects calcium absorption and use in physiological processes.
Area of Science:
- Animal coloration
- Biochemistry
- Physiological ecology
Background:
- Melanin-based coloration is typically heritable and unaffected by environment or condition.
- The handicap principle suggests coloration may not signal individual quality due to uniform costs.
- Eumelanin production requires calcium, potentially linking coloration to calcium-dependent physiological processes.
Purpose of the Study:
- To investigate if eumelanin-based coloration in barn owls is associated with calcium metabolism.
- To test the hypothesis that plumage spottiness reflects calcium allocation between pigment production and other bodily functions.
Main Methods:
- A correlative study was conducted on 85 barn owls.
- Calcium concentration was measured in the humerus (bone) of each owl.
- Plumage spottiness was assessed to correlate with bone calcium levels.
Main Results:
- Barn owls with more extensive eumelanic spotting exhibited higher calcium concentrations in their humeri.
- This finding suggests a link between plumage coloration and calcium availability or utilization.
- Heavily spotted owls may be better at absorbing dietary calcium for both pigment synthesis and bone storage.
Conclusions:
- Eumelanin-based coloration in barn owls is associated with calcium metabolism.
- Plumage spottiness may indicate an individual's capacity for calcium absorption and allocation.
- This challenges the notion that melanin coloration is a condition-independent signal, as it appears linked to physiological resource management.
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