Niche Theory is a central framework in ecology based on the recognition that most interactions between organisms are indirect, mediated by the biotic and abiotic dynamical environment these organisms live in. Despite its potential generality, the theory still mostly focuses on how resource–consumer dynamics mediate competition in ecological communities. However, it is being increasingly recognized that positive interactions between organisms also play an important role in driving the structure and functioning of ecological communities, from plants to microbes. In this paper, we present a unified theory of the niche that applies to both positive and negative interactions between organisms, mediated by one or two environmental factors. We show that classical concepts such as niche differences and fundamental and realized niches can naturally be expanded to facilitative and mutualistic interactions. In addition, we introduce and formalize new general niche concepts that appear exclusively in the presence of positive interactions: (1) the Allee niche, a region of environmental conditions for which a species can persist but not invade from low densities and (2) niche facilitation, when the presence of a species expands the set of environmental conditions under which a second species can invade and/or persist. To show the broad applicability of this theory, we illustrate these concepts using a diverse set of theoretical examples, from bacteria feeding on an inhibiting substrate, to nitrogen-fixing plants and the indirect mutualism between a plant and a carnivore species. In sum, our work shows how Niche Theory provides a natural framework for positive interactions in ecology, bringing a unified perspective and new conceptual tools to study ecological systems where these positive interactions occur.

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从竞争到促进和共生：利基的一般理论

生态位理论是生态学中的一个核心框架，它基于以下认识：生物体之间的大多数相互作用是间接的，由这些生物体生活的生物和非生物动力环境介导。生态群落的竞争。然而，人们越来越认识到，生物体之间的积极相互作用在推动从植物到微生物的生态群落的结构和功能方面也发挥着重要作用。在本文中，我们提出了一个统一的生态位理论，该理论适用于由一个或两个环境因素介导的生物体之间的积极和消极相互作用。我们表明，诸如利基差异以及基本和已实现的利基等经典概念可以自然地扩展为促进性和互惠性的相互作用。此外，我们引入并正式化了新的一般生态位概念，这些概念仅在存在积极相互作用的情况下出现：（1）Allee 生态位，一个物种可以持续存在但不能从低密度入侵的环境条件区域和（2）生态位促进，当一个物种的存在扩大了第二个物种可以入侵和/或持续存在的环境条件。为了展示该理论的广泛适用性，我们使用一组不同的理论例子来说明这些概念，从以抑制性基质为食的细菌，到固氮植物以及植物和食肉动物物种之间的间接共生。总共，