Data from: Dietary carotenoid availability affects avian color discrimination

Carotenoid pigments are found in the retinas of many vertebrate species, where they serve a range of functions. In birds, carotenoid-containing retinal oil droplets act as optical filters, modifying the light reaching the underlying visual pigment and thereby enhancing color vision. Dietary carotenoid manipulation is known to affect the allocation of carotenoids to the retina, although the effects this has on vision are less well understood. Using dietary manipulations, in which juvenile Japanese quail (Coturnix japonica) received either a high- or a low-carotenoid diet, we tested the effects of carotenoid availability on the ability to perform a color discrimination task. Birds on both diet treatments were able to make a relatively coarse discrimination between colors that appeared to humans as yellow-orange and orange; however, only high-carotenoid diet birds were able to make a finer-scale discrimination involving intermediate colors, showing that dietary carotenoid availability can directly affect the ability of birds to make chromatic discriminations. This finding has implications for our understanding of trade-offs in carotenoid allocation between vision and other key functions such as sexual ornamentation and health maintenance, and suggests that variation in dietary carotenoid availability may affect the ability of animals to make ecologically pertinent color discriminations, such as between sexual signals or cryptic food items.类胡萝卜素色素（Carotenoid pigments）广泛分布于多种脊椎动物的视网膜中，具备多种生理功能。在鸟类体内，含有类胡萝卜素的视网膜油滴可作为光学滤器，调节抵达下层视觉色素的光线，从而增强色觉表现。已有研究证实，膳食类胡萝卜素的调控会影响类胡萝卜素向视网膜的分配，但该过程对视觉功能的具体影响尚未得到充分解析。本研究通过膳食干预实验，为幼年日本鹌鹑（Coturnix japonica）分别饲喂高类胡萝卜素与低类胡萝卜素日粮，以此检验类胡萝卜素可获得性对其完成颜色辨别任务能力的影响。实验结果显示，两种日粮组的鹌鹑均能较为粗略地分辨人类视角下的黄橙色与橙色；但仅高类胡萝卜素日粮组的个体能够完成涉及中间色的精细辨别，这表明膳食类胡萝卜素的可获得性可直接影响鸟类的色彩辨别能力。该发现有助于理解类胡萝卜素在视觉功能与其他关键生理功能（如性饰发育与健康维持）之间的分配权衡关系，同时提示膳食类胡萝卜素可获得性的差异，可能会影响动物完成与生态相关的色彩辨别行为的能力，例如分辨性信号或隐蔽性食物。