School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, 68588, USA.
Ecology. 2020 Jan;101(1):e02911. doi: 10.1002/ecy.2911. Epub 2019 Nov 11.
Individual diet specialization appears widespread and has several ecological ramifications. Hypotheses on the causes of diet specialization generally assume prey preferences differ among predator individuals. They then predict how the magnitude of diet variation should change when ecological factors (e.g., intraspecific competition) alter prey abundances. However, the magnitude of diet variation is expected to change with prey abundances due to stochasticity in the foraging process even if all predators share the same prey preferences. Here I show that the relative prey abundance where diet variation is maximized and the magnitudes of diet variation in prey switching experiments are predicted well by a simple stochastic foraging model based only on relative prey abundances and a shared relative prey preference among predators. These results suggest that the effects of stochasticity during foraging may confound studies of individual diet specialization if these effects are not accounted for in experimental design or interpretation. Furthermore, the stochastic foraging model provides simple baseline expectations for theoretical studies on the ecological consequences of diet variation and offers a way forward on quantitative predictions of how ecological factors influence the magnitude of diet variation when stochasticity during foraging and diet specialization occur simultaneously. Last, this study highlights the continued importance of integrating stochasticity into mechanistic ecological hypotheses.
个体饮食专业化似乎很普遍，并且具有多种生态后果。关于饮食专业化原因的假说通常假设捕食者个体之间的猎物偏好存在差异。然后，它们预测当生态因素（例如种内竞争）改变猎物丰度时，饮食变化的幅度应该如何变化。然而，即使所有捕食者都具有相同的猎物偏好，由于觅食过程中的随机性，饮食变化的幅度也会随着猎物丰度的变化而变化。在这里，我表明，仅基于相对猎物丰度和捕食者之间共享的相对猎物偏好的简单随机觅食模型可以很好地预测饮食变化最大化时的相对猎物丰度和猎物转换实验中的饮食变化幅度。这些结果表明，如果在实验设计或解释中不考虑觅食过程中的随机性影响，那么在研究个体饮食专业化时，这些影响可能会混淆研究。此外，随机觅食模型为关于饮食变化的生态后果的理论研究提供了简单的基准预期，并为定量预测当觅食和饮食专业化同时发生时，生态因素如何影响饮食变化的幅度提供了一种方法。最后，这项研究强调了将随机性纳入机制生态假设的持续重要性。
