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在于：为何部分动物能够适应宽泛的饮食谱，而另一些动物的饮食选择却受到严格限制？相关理论预测，广食性动物在面临可获取食物的营养平衡受生态因素制约时，其宏量营养素（macronutrient）获取策略应具备灵活性；而在营养几何学（nutritional geometry）的建模框架中，这种灵活调控模式已被定量表征为‘等距调控模型（equal distance regulatory model）’。尽管已有多项昆虫实验室研究为该预测提供了实证支持，但目前尚无针对野外广食性动物或任何脊椎动物的相关验证。本研究开展了该项验证的首次尝试，基于2013至2015年三年间累计281次黎明至黄昏的焦点动物观测数据，研究对象为生态广适性仅次于人类的恒河猴（Macaca mulatta tcheliensis）。研究结果与理论预测一致：宏量营养素调控模式与等距调控模型高度契合，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。泌乳与非泌乳猕猴均独立呈现出这一规律，但泌乳雌性的宏量营养素摄入量显著更高，同时其非营养性食物组分——不可消化膳食纤维与单宁——的摄入水平也显著提升。该结果表明，非泌乳猕猴的等距调控并非受食物可获取性受限、膳食纤维或植物单宁摄入存在上限等制约因素所导致的假象，而是针对膳食宏量营养素平衡变化的战略性调控响应。本研究最后探讨了本研究结果对作为所有灵长类中广食性最强的人类的研究启示。