Am Nat. 2020 Aug;196(2):132-144. doi: 10.1086/709479. Epub 2020 Jul 6.
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 () 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.
生态压力，如竞争，可以导致种群内的个体分割资源或栖息地，但决定个体资源利用的内在机制尚不清楚。在这里，我们表明，个体自身的能量需求和相关的竞争能力会影响其资源利用，但只有在食物更受限制时才会如此。我们测试了种内代谢率的变化是否会导致在受人为控制的营养水平和随后的人均食物供应影响的天然溪流中，幼年大西洋鲑（）的微生境分割。我们发现，来自基础（标准）代谢率较高的家族的个体鲑鱼（这与更高的竞争能力有关）往往占据流速较快的水，但仅在人均食物供应较低的溪流中。流速较快的小生境产生更多的食物，但高代谢率的鱼类只有在高食物水平的溪流中才能从更快的生长中受益，大概是因为在低食物环境中，高代谢率的代价抵消了获得多产小生境的好处。因此，给定代谢率的好处取决于具体情况。这些结果表明，种内代谢率的变化可以与资源可用性相互作用，从而决定野生种群的空间结构。
