Data from: Macronutrient signature of dietary generalism in an ecologically diverse primate in the wild

A question of considerable importance is why some animals are able to succeed on a wide range of diets while others are more tightly constrained. Theory predicts that generalists should show a flexible response for macronutrient acquisition in the face of ecologically-driven constraint on the nutritional balance of available foods, which in the modelling framework of nutritional geometry has been quantitatively characterized as an “equal distance” regulatory model. This prediction, which has empirical support from several laboratory studies on insects, has not been tested for any generalist animal in the wild, nor for any vertebrate. We performed the first such test, using 281 dawn-to-dusk focal animal observations over three years (2013-2015) of Rhesus macaques monkeys (Macaca mulatta tcheliensis), a primate that is second only to humans in ecological generalism. Results showed, as predicted, that macronutrient regulation conformed closely to the equal distance pattern, and differed markedly from the other, ecologically more-specialized primate species that have been studied to date. The same was independently true for lactating and non-lactating macaques, but lactating females had substantially higher intake of macronutrients, as well as the non-nutritional food components, indigestible fiber and tannins. This demonstrates that equal distance regulation by non-lactating monkeys was not an artefact of constraint such as restricted food availability or an upper limit to the ingestion of dietary fiber or plant tannins, but a strategic regulatory response to variation in dietary macronutrient balance. We discuss implications of our results for the most generalist primate of all, humans.一个极具研究价值的核心问题是：为何部分动物能够适应多样化的膳食结构，而另一些动物的食性却受到更为严格的限制？理论预测：当可获得食物的营养平衡受到生态因素制约时，广食性动物应在宏量营养素（macronutrient）获取方面表现出灵活的调节策略；而在营养几何学（nutritional geometry）的建模框架中，这类调节模式被定量定义为‘等距’（equal distance）调节模型。该预测虽已在多项昆虫实验室研究中获得实证支持，但尚未在野生广食性动物或任何脊椎动物类群中得到验证。本研究首次开展此类验证：我们对太行恒河猴（Macaca mulatta tcheliensis）开展了为期三年（2013-2015年）的281次从黎明到黄昏的目标动物追踪观测，该灵长类的生态广食性仅次于人类。研究结果正如预测所示：宏量营养素调节模式与‘等距’模型高度契合，且与迄今已被研究的其他生态特化灵长类物种存在显著差异。泌乳与非泌乳恒河猴均呈现出这一规律，但泌乳雌性的宏量营养素摄入量显著更高，同时其对非营养性食物组分——不可消化膳食纤维与单宁——的摄入也更多。这表明非泌乳恒河猴的‘等距’调节模式并非受食物可获得性受限、膳食纤维或植物单宁摄入存在上限等约束因素导致的人为假象，而是针对膳食宏量营养素平衡变化的战略性调节响应。本研究最后讨论了该结果对作为最极致广食性灵长类的人类的启示。