Eat yourself sexy: how selective macronutrient intake influences the expression of a visual signal in common mynas

These datasets and programs were analyzed in the manuscript 'Eat yourself sexy: how selective macronutrient intake influences the expression of a visual signal in common myna'.

Producing colored signals often requires consuming dietary carotenoid pigments. Evidence that food deprivation can reduce coloration, however, raises the question of whether other dietary nutrients contribute to signal coloration, and furthermore, whether individuals can voluntarily select food combinations to achieve optimal coloration. We created a two-way factorial design to manipulate macronutrient and carotenoid access in common mynas (Acridotheres tristis) and measured eye patch coloration as a function of the food combinations individuals selected. Mynas had access to either water or carotenoid-supplemented water and could either eat a standard captive diet or choose freely between three nutritionally defined pellets (protein, lipid or carbohydrate). Mynas supplemented with both carotenoids and macronutrient pellets had higher color scores than control birds. Male coloration tended to respond more to nutritional manipulation than females, with color scores improving in macronutrient- and carotenoid-supplemented individuals compared with controls. All mynas consuming carotenoids had higher levels of plasma carotenoids, but only males showed a significant increase by the end of the experiment. Dietary carotenoids and macronutrient intake consumed in combination tended to increase plasma carotenoid concentrations the most. These results demonstrate for the first time that consuming specific combinations of macronutrients along with carotenoids contributes to optimizing a colorful signal, and point to sex-specific nutritional strategies. Our findings improve our knowledge of how diet choices affect signal expression and, by extension, how nutritionally impoverished diets, such as those consumed by birds in cities, might affect sexual selection processes and, ultimately, population dynamics.

本数据集与程序的分析均基于学术论文《食以焕彩：选择性宏营养素摄入如何影响家八哥视觉信号的表达》。

有色信号的产生通常需要摄入膳食类胡萝卜素。然而，已有研究证实食物匮乏会降低体色表现，这引发了两个核心问题：其一，是否存在其他膳食营养素可助力信号体色的形成；其二，个体能否主动选择食物组合以实现最优体色表现。

本研究以家八哥（学名：Acridotheres tristis）为实验对象，采用双因素析因设计操控宏营养素与类胡萝卜素的摄入途径，并基于个体选择的食物组合，对其眼斑体色进行量化测定。实验中，家八哥可选择饮用普通水或添加类胡萝卜素的水，同时既可选择食用标准笼养日粮，也可自由选取三种营养组分明确的颗粒饲料（分别为蛋白质、脂质或碳水化合物）。

结果显示，同时补充类胡萝卜素与宏营养素颗粒饲料的家八哥，其体色评分显著高于对照组个体。相较于雌性家八哥，雄性的体色对营养操控的响应更为显著：补充宏营养素与类胡萝卜素的个体，其体色评分较对照组有所提升。所有摄入类胡萝卜素的家八哥，其血浆类胡萝卜素水平均更高，但仅雄性个体在实验结束时出现了显著升高。同时摄入膳食类胡萝卜素与宏营养素的个体，其血浆类胡萝卜素浓度的提升最为显著。

本研究首次证实，同时摄入特定组合的宏营养素与类胡萝卜素，有助于优化有色信号的表达，并揭示了性别特异性的营养策略。本研究结果深化了我们对饮食选择如何影响信号表达的认知，并进一步推知，城市鸟类所摄入的营养匮乏日粮，可能会对性选择过程乃至最终的种群动态产生何种影响。