Ontogenetic Diet Shifts Result in Niche Partitioning between Two Consumer Species Irrespective of Competitive Abilities
Ontogenetic Diet Shifts Result in Niche Partitioning between Two Consumer Species Irrespective of Competitive Abilities
复制标题
无论竞争能力如何，个体发育饮食变化都会导致两个消费者物种之间的利基划分
作者：
T. Schellekens;A. D. de Roos;L. Persson
蒂尔曼的理论根据零净增长等斜线（ZNGI）的形状预测了共享两种资源的两个消费者之间的竞争结果。在他的理论中，没有考虑资源利用的种内差异。在这里，我们将这一理论扩展到包括生物体经历个体发生饮食变化的情况，因为这些变化是许多物种生命史的特征。在没有饮食转变会导致消费物种中性共存的情况下，我们研究个体发育饮食转变是否会导致生态位划分。我们分析了一个模型，该模型描述了两个在个体发育方面具有独特饮食的竞争者之间对两种资源的竞争，使用桡足类（显示个体发育饮食变化）和水蚤（不显示个体发育饮食变化）作为适当的代表。我们表明，个体发生饮食的转变会影响 ZNGI 的形状，将其从反映完全可替代的资源转变为反映基本资源。此外，我们发现资源供应决定了桡足类的种群阶段结构和阶段依赖的资源消耗，并影响与水蚤的竞争结果。特别是，我们表明，如果成人资源的供应低于青少年资源的供应，个体发育饮食转变本身可以提供竞争优势，但如果成人资源的供应超过青少年资源，它总是会导致劣势。
Tilman’s theory predicts the outcome of competition between two consumers sharing two resources on the basis of the shape of zero net‐growth isoclines (ZNGIs). In his theory, intraspecific differences in resource use are not accounted for. Here we extend this theory to include situations where organisms undergo ontogenetic diet shifts, as these characterize the life histories of many species. In a situation that without diet shifts would lead to neutral coexistence of consumer species, we investigate whether ontogenetic diet shifts lead to niche partitioning. We analyze a model describing competition for two resources between two competitors with distinctive diets over ontogeny, using copepods (showing ontogenetic diet shifts) and daphnids (not showing ontogenetic diet shifts) as appropriate representatives. We show that an ontogenetic diet shift affects the shape of the ZNGI, changing it from reflecting perfectly substitutable resources to reflecting essential resources. Furthermore, we show that resource supply determines population stage structure and stage‐dependent resource consumption in copepods and influences the competitive outcome with daphnids. In particular, we show that in itself, an ontogenetic diet shift can provide a competitive advantage if the supply of the adult resource is lower than the supply of the juvenile resource but that it always causes a disadvantage if the supply of the adult resource exceeds that of the juvenile resource.