Ecological pressures such as competition can lead individuals within a population to partition resources or habitats, but the underlying intrinsic mechanisms that determine an individual’s resource use are not well understood. Here we show that an individual’s own energy demand and associated competitive ability influence its resource use, but only when food is more limiting. We tested whether intraspecific variation in metabolic rate leads to microhabitat partitioning among juvenile Atlantic salmon (Salmo salar) in natural streams subjected to manipulated nutrient levels and subsequent per capita food availability. We found that individual salmon from families with a higher baseline (standard) metabolic rate (which is associated with greater competitive ability) tended to occupy faster-flowing water, but only in streams with lower per capita food availability. Faster-flowing microhabitats yield more food, but high metabolic rate fish only benefited from faster growth in streams with high food levels, presumably because in low-food environments the cost of a high metabolism offsets the benefits of acquiring a productive microhabitat. The benefits of a given metabolic rate were thus context dependent. These results demonstrate that intraspecific variation in metabolic rate can interact with resource availability to determine the spatial structuring of wild populations.

中文翻译：

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代谢率与资源可用性相互作用，以确定在野外使用微生境的个体差异。

竞争之类的生态压力可能导致种群中的个体划分资源或栖息地，但是决定个体资源利用的内在机制却未得到很好的理解。在这里，我们证明了个人自身的能源需求和相关的竞争能力会影响其资源使用，但前提是食物的限制更大。我们测试了种内代谢速率的变化是否导致幼大西洋大西洋鲑（Salmo salar）中的微生境分配）中的自然溪流受到可控的营养水平和随后人均食物供应的影响。我们发现，来自基线（标准）代谢率较高（与更高的竞争能力相关）的家庭的鲑鱼往往会占据流动速度较快的水，但仅在人均食物利用率较低的溪流中占据。流动速度更快的微生境可提供更多的食物，但高代谢率的鱼类仅得益于食物水平高的溪流中更快的生长，这大概是因为在低食物环境中，高代谢的成本抵消了获得生产性微栖息地的好处。因此，给定代谢率的益处取决于上下文。