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The work of Sheppard et al. (Ecol. Lett., 21, 2018, 1395) relies on the strong assumption that isotopic niche is equal to trophic niche. Here I raise three main concerns showing that classic hypotheses built upon trophic niche cannot be directly interpreted in isotopic space. Future studies should always keep isotopic and trophic niches distinct.

谢泼德等人（Ecol. Lett.，21，2018，1395）的工作依赖于一个强有力的假设，即同位素生态位等于营养生态位。在这里，我提出了三个主要关注点，表明基于营养生态位的经典假设不能直接在同位素空间中解释。未来的研究应该始终保持同位素生态位和营养生态位的区别。