A test of the niche variation hypothesis in a ruminant herbivore

1. Despite the shared prediction that the width of a population’s dietary niche expands as food becomes limiting, the Niche Variation Hypothesis (NVH) and Optimal Foraging Theory (OFT) offer contrasting views about how individuals alter diet selection when food is limited.

2. Classical OFT predicts that dietary preferences do not change as food becomes limiting, so individuals expand their diets as they compensate for a lack of preferred foods. In contrast, the NVH predicts that among-individual variation in cognition, physiology, or morphology create functional trade-offs in foraging efficiency, thereby causing individuals to specialize on different subsets of food.

3. To evaluate (a) the predictions of the NVH and OFT and (b) evidence for physiological and cognitive-based functional trade-offs, we used DNA microsatellites and metabarcoding to quantify the diet, microbiome, and genetic relatedness (a proxy for social learning) of 218 moose (Alces alces) across six populations tha...

1. 尽管学界普遍预测，种群的饮食生态位宽度会随食物匮乏而拓宽，但生态位变异假说（Niche Variation Hypothesis, NVH）与最优觅食理论（Optimal Foraging Theory, OFT）在食物匮乏时个体如何调整食谱选择这一问题上持有相悖观点。
2. 经典最优觅食理论预测，食物匮乏时个体的饮食偏好不会发生改变，因此它们会通过拓宽食谱来弥补偏好食物的不足。与之相对，生态位变异假说则认为，个体间在认知、生理或形态上的差异会导致觅食效率上的功能性权衡，进而促使个体特化利用不同的食物类群。
3. 为验证（a）生态位变异假说与最优觅食理论的预测，以及（b）基于生理与认知的功能性权衡相关证据，我们利用DNA微卫星（DNA microsatellites）与元条形码（metabarcoding）技术，对6个种群共218头驼鹿（Alces alces）的食谱、微生物组以及遗传相关性（作为社会学习的替代指标）进行了定量分析，研究覆盖了6个种群的……