Eggshell coloration reflects both yolk characteristics and dietary carotenoid history of female mallards

1. Avian eggshell coloration has frequently been examined in a functional context (e.g. mimicry, camouflage), but in recent years, an interest has emerged in identifying the mechanisms that drive eggshell colour variation. 2. Eggshell coloration is predominately caused by pigment deposition; one such pigment is the antioxidant biliverdin, and deposition of biliverdin into eggshells may be costly to mothers due to depletion of their antioxidant reserves. Previous work has shown that dietary supplementation during laying with another type of antioxidant – carotenoid pigments – induces females to produce more biliverdin-rich eggshells. However, the impact of pre-laying nutrition – including the developmental period early in life – on eggshell coloration has not been investigated. 3. Here, we raised female mallards (Anas platyrhynchos) from hatching, supplemented their diets with carotenoids during early-, mid- or late-developmental periods, and at adulthood measured female circulating caro...1. 鸟类蛋壳颜色的相关研究常以功能视角展开（如拟态、伪装），但近年来学界逐渐兴起对蛋壳颜色变异驱动机制的探究兴趣。 2. 蛋壳颜色主要由色素沉积所主导，其中一类关键色素为抗氧化剂胆绿素（biliverdin）。母体将胆绿素沉积至蛋壳的过程，会因消耗自身抗氧化储备而产生生理代价。已有研究证实，产蛋期日粮中补充另一类抗氧化剂——类胡萝卜素（carotenoid pigments）——可促使雌鸟生成胆绿素含量更高的蛋壳。然而，产蛋前的营养状况（包括生命早期发育阶段）对蛋壳颜色的影响尚未得到相关研究。 3. 本研究从孵化阶段开始饲养雌性绿头鸭（Anas platyrhynchos），分别在其发育早期、中期与晚期的日粮中添加类胡萝卜素，并于成年后检测雌鸟循环系统中的类胡萝卜素（原文此处存在截断）。