Biotic resistance is often posited, but rarely known, to be the cause of invasion failure. Competition and predation are the most frequently identified processes that may prevent or limit the establishment of nonnative species. Interactions between nonnative and native species that involve intraguild predation (IGP) are very common in nature, although theory predicts most IGP systems should be unstable and lead to extinction. If this prediction is true, the frequency of invasion failures due to IGP may be underappreciated because of their fleeting nature and, thus, studies of unstable IGP systems are lacking, despite the opportunities they offer for understanding the factors affecting their unstable dynamics. We investigated a failed invasion involving an IGP relationship. In Florida, the guppy (Poecilia reticulata), a worldwide invader, fails to establish in the presence of eastern mosquitofish (Gambusia holbrooki). We tested whether and how resident mosquitofish cause guppy invasion failure using replicated mesocosm and aquarium trials. Both the predator and competitor components of the IGP relationship were strongly asymmetrical, with large impacts on guppies. We identified two effects, direct consumption of neonates and aggressive interference competition, that limited survival and recruitment. The highly unstable nature of this IGP relationship is the primary cause of the failure of the guppy to establish in Florida. Our study shows that the transient nature of an ephemeral IGP relationship can yield important insights into the underlying causes of invasion failure, including the role of strong biotic resistance.

中文翻译：

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不稳定的行内捕食导致全球入侵物种的建立失败

生物抗性通常被认为是入侵失败的原因，但鲜为人知。竞争和捕食是最常见的可能阻止或限制非本地物种建立的过程。涉及行内捕食 (IGP) 的非本地和本地物种之间的相互作用在自然界中非常普遍，尽管理论预测大多数 IGP 系统应该不稳定并导致灭绝。如果这个预测是真的，由于 IGP 入侵失败的频率可能会被低估，因为它们是短暂的，因此缺乏对不稳定 IGP 系统的研究，尽管它们提供了理解影响其不稳定动力学的因素的机会。我们调查了涉及 IGP 关系的失败入侵。在佛罗里达州，孔雀鱼 ( Poecilia reticulata)，一个世界性的入侵者，未能在东部蚊鱼( Gambusia holbrooki )的存在下建立。我们使用重复的中胚层和水族馆试验测试了常驻蚊鱼是否以及如何导致孔雀鱼入侵失败。IGP 关系的捕食者和竞争者成分都非常不对称，对孔雀鱼影响很大。我们确定了两种影响，即直接消耗新生儿和积极的干扰竞争，它们限制了生存和招募。这种 IGP 关系的高度不稳定性质是孔雀鱼未能在佛罗里达州建立的主要原因。我们的研究表明，短暂的 IGP 关系的短暂性可以对入侵失败的根本原因产生重要的见解，包括强大的生物抗性的作用。