Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.
Oecologia. 2010 Sep;164(1):65-71. doi: 10.1007/s00442-010-1680-7. Epub 2010 Jun 13.
The intensity of selection exerted on ornaments typically varies between environments. Reaction norms may help to identify the conditions under which ornamented individuals have a selective advantage over drab conspecifics. It has been recently hypothesized that in vertebrates eumelanin-based coloration reflects the ability to regulate the balance between energy intake and expenditure. We tested two predictions of this hypothesis in barn owl nestlings, namely that darker eumelanic individuals have a lower appetite and lose less weight when food-deprived. We found that individuals fed ad libitum during 24 h consumed less food when their plumage was marked with larger black spots. When food-deprived for 24 h nestlings displaying larger black spots lost less weight. Thus, in the barn owl the degree of eumelanin-based coloration reflects the ability to withstand periods of food depletion through lower appetite and resistance to food restriction. Eumelanic coloration may therefore be associated with adaptations to environments where the risk of food depletion is high.
选择对装饰物施加的强度通常在环境之间变化。反应规范可以帮助确定有装饰的个体相对于单调的同种个体具有选择优势的条件。最近有人假设，在脊椎动物中，基于真黑素的颜色反映了调节能量摄入和支出之间平衡的能力。我们在仓鸮雏鸟中测试了这一假设的两个预测，即黑色素含量较高的个体在饥饿时食欲较低，体重减轻较少。我们发现，当羽毛上有较大的黑色斑点时，24 小时内自由进食的个体消耗的食物较少。当饥饿 24 小时时，显示出较大黑色斑点的雏鸟减轻的体重较少。因此，在仓鸮中，基于真黑素的颜色程度反映了通过较低的食欲和对食物限制的抵抗力来承受食物匮乏期的能力。因此，真黑素颜色可能与适应食物匮乏风险高的环境有关。
