Life-history theory provides a framework for detecting resource limitation: a test of the Nutritional Buffer Hypothesis

For ungulates and other long-lived species, life-history theory predicts that nutritional reserves are allocated to reproduction in a state-dependent manner because survival is highly conserved. Further, as per-capita food abundance and nutritional reserves decline (i.e., density-dependence intensifies), reproduction and recruitment become increasingly sensitive to weather. Thus, the degree to which weather influences vital rates should be associated with proximity to nutritional carrying capacity—a notion that we refer to as the Nutritional Buffer Hypothesis. We tested the Nutritional Buffer Hypothesis using six moose (Alces alces) populations that varied in calf recruitment (33-69 calves/ 100 cows). We predicted that populations with high calf recruitment were nutritionally buffered against the effects of unfavorable weather, and thus were below nutritional carrying capacity. We applied a suite of tools to quantify habitat and nutritional condition of each population and found that in...

针对有蹄类动物（ungulates）及其他长寿命物种，生活史理论（life-history theory）预测：由于存活率高度保守，营养储备会以状态依赖的方式分配至繁殖活动。进一步而言，随着人均食物丰度与营养储备下降（即密度制约作用增强），繁殖与种群补充对天气的敏感性会逐步提升。由此可见，天气对种群生命率的影响程度，应当与种群接近营养承载力（nutritional carrying capacity）的程度紧密相关——这一学术观点我们将其命名为营养缓冲假说（Nutritional Buffer Hypothesis）。我们选取6个驼鹿（Alces alces）种群开展检验，这些种群的幼崽补充率跨度为33~69头幼崽/100头母牛。我们提出如下预测：幼崽补充率较高的种群，其营养条件能够缓冲不利天气带来的影响，因此这类种群的实际营养状态低于营养承载力。我们运用一系列研究工具量化了各研究种群的栖息地与营养状况，并发现……