Explaining nature’s biodiversity is a key challenge for science. To persist, populations must be able to grow faster when rare, a feature called negative frequency dependence and quantified as ‘niche differences’ () in modern coexistence theory. Here, we first show that available definitions of differ in how link to species interactions, are difficult to interpret and often apply to specific community types only. We then present a new definition of that is intuitive and applicable to a broader set of (modelled and empirical) communities than is currently the case, filling a main gap in the literature. Given , we also redefine fitness differences () and illustrate how and determine coexistence. Finally, we demonstrate how to apply our definitions to theoretical models and experimental data, and provide ideas on how they can facilitate comparison and synthesis in community ecology.

中文翻译：

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利基和适应性差异的直观且广泛适用的定义。

解释自然的生物多样性是科学的关键挑战。为了保持生存，种群必须能够在稀有情况下更快地增长，这一特征称为负频率依赖性，在现代共存理论中被量化为“利基差异”（）。在这里，我们首先表明，对物种相互作用的联系方式的可用定义不同，难以解释，并且通常仅适用于特定的社区类型。然后，我们提出了一个新的定义，它比目前的情况更直观，并且适用于更广泛的（建模和经验）社区集合，填补了文献中的主要空白。给定，我们还重新定义了适应性差异（），并说明了如何以及确定共存。最后，我们演示了如何将我们的定义应用于理论模型和实验数据，并就它们如何促进社区生态学中的比较和综合提供了思路。