The Molecular Costs of Being Sexually Attractive: a Quantitative Assessment of Carotenoid Limitations for Coloration and Self-Maintenance

几个世纪以来，生物学家一直着迷于动物的夸张特征（如鹿的角拉长，鸟的叫声复杂）。进化理论预测，这些“装饰品”的生产成本很高，因此可以作为个体对潜在伴侣或竞争对手价值的可靠指标。尽管对动物交流进行了几十年的研究，但产生这种信号的真正内在的分子成本却很少确定。研究人员将使用比较营养、生化、免疫学和形态学的方法来调查鸟类产生一种常见的夸张特征的成本：基于类胡萝卜素的华丽羽毛颜色。在许多鸟类中，颜色最鲜艳的个体被首选为配偶。羽毛从黄色到红色的类胡萝卜素着色需要从食物中获得色素（如西红柿和玉米），但这些色素对自我维护（即抗氧化防御，免疫调节）也很有价值。这种使用类胡萝卜素色素的潜在权衡是测试营养限制如何双重控制个体的性特征表达和健康质量的最佳选择。研究人员将研究类胡萝卜素的摄入、分配和颜色，野生鸟类长出多彩的羽毛，圈养鸟类的饮食中类胡萝卜素含量系统地变化。他们将使用五对密切相关的鸟类（即黑鸟、麻雀、鸭子），其中一种显示类胡萝卜素的颜色，另一种没有，以测试在不同的获取和利用需求下如何分配类胡萝卜素的预测。这项研究将为人类和家畜抗氧化剂与健康的研究提供有价值的基础。研究结果将在科学和非专业人士（如杂志）论坛上发表，以促进更广泛受众的科学学习。我们的机构和社区内的本科生、少数民族和青年学者将在不同领域进行培训。对五颜六色的后院鸟类的实地考察将促进与公众的合作和信息共享。

For centuries, biologists have been captivated by exaggerated features in animals (i.e. elongated horns in deer, elaborate bird songs). Evolutionary theory predicts that these 'ornaments' are costly to produce and thus serve as reliable indicators of an individual's worth to potential mates or rivals. Despite several decades of research on animal communication, the true intrinsic, molecular costs that go into producing such signals are poorly established. The investigators will use comparative nutritional, biochemical, immunological, and morphological approaches to investigate the costs of producing a common exaggerated trait in birds: ornate carotenoid-based plumage coloration. In many bird species, the most brightly colored individuals are preferred as mates. Yellow-to-red carotenoid coloration of feathers requires pigments obtained from food (like in tomatoes and corn), but these same pigments are also valuable for self-maintenance (i.e. antioxidant defense, immunomodulation). This potential trade-off in use of carotenoid pigments is optimal for testing how nutrient limitations dually govern the sexual trait expression and health quality of individuals. The investigators will study carotenoid intake, allocation, and coloration in wild birds growing their colorful feathers as well as in captive birds fed diets varying systematically in carotenoid content. They will use five pairs of closely related bird species (i.e. blackbirds, sparrows, ducks), one of which shows carotenoid coloration and the other of which does not, in order to test predictions about how carotenoids are apportioned under varying acquisitional and utilizational demands. This research will contribute to valuable bodies of work on antioxidants and health in humans and domestic animals. Results will be published in scientific and layperson (e.g. magazines) forums to foster scientific learning among broader audiences. Undergraduate, minority, and youth scholars within our institutions and communities will be trained in diverse fields. Fieldwork on colorful backyard birds will stimulate collaborations and information sharing with the public.