Interspecific competition, a dominant process structuring ecological communities, is influenced by species' phenotypic differences. Limiting similarity theory holds that species with similar traits should compete intensely (‘trait‐similarity'). In contrast, competing theories including modern coexistence theory emphasize that species with traits conferring competitive advantages should outcompete others (‘trait‐hierarchy'). Either or both of these mechanisms may drive competitive exclusion, but their relative importance and interacting effects are rarely studied. Here, we explore empirically whether trait‐similarity and trait‐hierarchy can explain fine‐scale spatial associations observed between invasive and native ant species in a tropical assemblage. We find that pairwise co‐occurrences between the invasive red imported fire ant Solenopsis invicta and 28 other species across relatively homogenous grasslands can be explained largely by an interaction of trait‐similarity and trait‐hierarchy in a single morphological trait, relative pronotum width. Specifically, higher trait‐hierarchy values are associated with negative co‐occurrences; however, these effects are counteracted when species are increasingly dissimilar in their trait ranges. These findings are consistent with the notion that limiting similarity and competitive hierarchies are interactive rather than discrete mechanisms driving competitive exclusion.

中文翻译：

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性状相似性和性状层次共同决定了居住和入侵蚂蚁物种的精细尺度空间关联

种间竞争是构成生态群落的主要过程，受物种表型差异的影响。限制相似性理论认为，具有相似性状的物种应竞争激烈（“性状-相似性”）。相反，包括现代共存理论在内的竞争理论则强调具有赋予竞争优势的特征的物种应胜过其他物种（“特征-等级”）。这两种机制中的一种或两种都可能导致竞争排斥，但是很少研究它们的相对重要性和相互作用。在这里，我们从经验上探索性状相似性和性状等级制度是否可以解释热带组合中入侵性和本地蚂蚁物种之间观察到的精细空间关联。我们发现入侵红色火蚁之间成对共现在相对同质的草原上的狼尾草和其他28个物种在很大程度上可以解释为单一形态性状（相对前胸膜宽度）中性状相似性和性状层次的相互作用。具体而言，较高的性状层次结构值与否定共现相关联。但是，当物种的性状范围越来越不相同时，这些影响就会被抵消。这些发现与以下观点一致：限制相似性和竞争等级是互动的，而不是驱动竞争排斥的离散机制。