Roulin Alexandre, Dauwe Tom, Blust Ronny, Eens Marcel, Beaud Michel
Department of Ecology and Evolution, University of Lausanne, Biology Building, 1015 Lausanne, Switzerland.
Naturwissenschaften. 2006 Sep;93(9):426-30. doi: 10.1007/s00114-006-0128-8. Epub 2006 Jun 24.
In many animals, melanin-based coloration is strongly heritable and is largely insensitive to the environment and body condition. According to the handicap principle, such a trait may not reveal individual quality because the production of different melanin-based colorations often entails similar costs. However, a recent study showed that the production of eumelanin pigments requires relatively large amounts of calcium, potentially implying that melanin-based coloration is associated with physiological processes requiring calcium. If this is the case, eumelanism may be traded-off against other metabolic processes that require the same elements. We used a correlative approach to examine, for the first time, this proposition in the barn owl, a species in which individuals vary in the amount, size, and blackness of eumelanic spots. For this purpose, we measured calcium concentration in the left humerus of 85 dead owls. Results showed that the humeri of heavily spotted individuals had a higher concentration of calcium. This suggests either that plumage spottiness signals the ability to absorb calcium from the diet for both eumelanin production and storage in bones, or that lightly spotted individuals use more calcium for metabolic processes at the expense of calcium storage in bones. Our study supports the idea that eumelanin-based coloration is associated with a number of physiological processes requiring calcium.
在许多动物中，基于黑色素的体色具有很强的遗传性，并且在很大程度上不受环境和身体状况的影响。根据 handicap 原理，这样的性状可能无法揭示个体质量，因为产生不同的基于黑色素的体色通常需要相似的成本。然而，最近的一项研究表明，真黑色素的产生需要相对大量的钙，这可能意味着基于黑色素的体色与需要钙的生理过程有关。如果是这样，真黑色素沉着可能会与其他需要相同元素的代谢过程进行权衡。我们首次采用相关方法在仓鸮中检验这一命题，仓鸮个体的真黑色素斑点在数量、大小和黑色程度上存在差异。为此，我们测量了 85 只死亡仓鸮左肱骨中的钙浓度。结果表明，斑点多的个体的肱骨钙浓度较高。这表明，要么羽毛斑点表明了从饮食中吸收钙用于真黑色素产生和骨骼储存的能力，要么斑点少的个体将更多的钙用于代谢过程，而牺牲了骨骼中的钙储存。我们的研究支持了基于真黑色素的体色与许多需要钙的生理过程相关的观点。
