Abstract Native wildlife are impacted by invasive species in numerous ways and will be more vulnerable if they cannot recognize the threat posed by an invader. Impacts, however, are generally assessed for a single life stage and without consideration of behavioral responses. This limits knowledge of the mechanisms underpinning the threats of invaders and the responses that could help or hinder native animals to mitigate this threat. We conducted a series of experiments to examine if the threat of an invader and behavioral responses by a native animal are life-stage dependent. Our focal species were a widespread invasive (Gambusia holbrooki) and a threatened native Australian freshwater fish (Galaxiella pusilla). We show that the threat of, and behavioral responses to, the invader vary across life-cycle stages. Gambusia holbrooki had different effects on G. pusilla: inhibiting reproduction and consuming larvae but not eating eggs or reducing adult growth and survival. Although larval G. pusilla avoided visual cues from G. holbrooki, native predators and conspecific adults, they did not avoid olfactory cues from G. holbrooki, which is maladaptive considering the predation risk. In addition, adult G. pusilla did not avoid any G. holbrooki cues, providing further evidence of maladaptive behavior. Our study is one of the first comprehensive evaluations of how the threats of an invader to a native species, as well as the responses to this threat, are life-stage dependent. We use our empirical results to develop a general framework for understanding the mechanisms by which invasives threaten native biota, and highlight how this can be used to help assess and mitigate the threat of invaders.

中文翻译：

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对入侵物种的行为反应和健康后果取决于受威胁的本地鱼类的生命阶段

摘要 本土野生动物以多种方式受到入侵物种的影响，如果它们无法识别入侵者构成的威胁，它们将更加脆弱。然而，影响通常是针对单个生命阶段进行评估的，而不考虑行为反应。这限制了对支持入侵者威胁的机制的了解，以及可能帮助或阻碍本地动物减轻这种威胁的反应。我们进行了一系列实验来检查入侵者的威胁和本土动物的行为反应是否与生命阶段有关。我们的焦点物种是一种广泛的入侵物种（Gambusia holbrooki）和一种受威胁的澳大利亚本土淡水鱼（Galaxiella pusilla）。我们表明，入侵者的威胁和行为反应在生命周期阶段各不相同。Gambusia holbrooki 对 G. pusilla 有不同的影响：抑制繁殖和消耗幼虫但不吃卵或减少成虫的生长和存活。尽管幼虫 G. pusilla 避免了来自 G. holbrooki、本地捕食者和同种成虫的视觉线索，但它们并没有避免来自 G. holbrooki 的嗅觉线索，考虑到捕食风险，这是不适应的。此外，成年 G. pusilla 没有避免任何 G. holbrooki 线索，提供了适应不良行为的进一步证据。我们的研究是对入侵者对本地物种的威胁以及对这种威胁的反应如何与生命阶段相关的首次综合评估之一。我们使用我们的实证结果来开发一个通用框架，以了解入侵者威胁本地生物群的机制，