Abstract

Variation in morphological, genetic, or behavioural traits within and among native species can modify vulnerability to impacts from an invasive species. If an individual’s vulnerability depends upon its cognitive performance, we may see adaptive shifts in cognitive traits post-invasion. Commonly, animals with enhanced cognitive abilities perform better in novel tasks, often by prioritising decision accuracy over decision speed. In eastern Australia, giant monitor lizards (Varanus varius) are fatally poisoned if they ingest invasive cane toads (Rhinella marina), but vulnerability is lower for individuals that carefully evaluate the novel prey type before swallowing it. To test if toad-imposed selection for neophobia and caution affected cognitive performance, we tested free-ranging monitors with a device that required lizards to manipulate the apparatus in order to obtain food. Success at accomplishing that task, and the speed of that success, was lower and slower in lizards from long-colonised sites than from uninvaded sites. Our results suggest that toad invasion has modified cognitive phenotypes within populations of this apex predator, a change that might have substantial effects on other species.

Significance statement

Many studies of the impacts of biological invasions focus on the numerical effect of an invader on the abundances of native taxa, neglecting other types of impacts. Colonising taxa can also impose selection on behavioural traits of native species, generating shifts in behaviour as native taxa adapt to intruders. Such shifts in behaviour are interesting not only in their own right but also because such shifts (especially in apex predators) may influence other taxa within food webs. Importantly, the nature and magnitude of such shifts may change over time post-invasion.

中文翻译：

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入侵蟾蜍蟾蜍（Rhinellla marina）会影响弱势捕食者（监控蜥蜴，Varanus varius）的解决问题性能

摘要

本地物种内部和之中的形态，遗传或行为特征的变化可以改变对入侵物种影响的脆弱性。如果一个人的脆弱性取决于其认知能力，我们可能会看到入侵后认知特征的适应性变化。通常，具有增强的认知能力的动物通常通过优先考虑决策准确性而不是决策速度来在新任务中表现更好。在澳大利亚东部，巨型监控蜥蜴（Varanus varius）如果摄入侵入性的蟾蜍蟾蜍，则会致命中毒（Rhinella marina），但对于在吞食新猎物之前仔细评估其类型的个体，脆弱性较低。为了测试蟾蜍对新恐惧症的选择并注意是否会影响认知能力，我们使用需要蜥蜴操纵该设备才能获取食物的设备测试了自由放养的显示器。在长殖民地的蜥蜴中，完成任务的成功率和成功速度要比未入侵的蜥蜴要低。我们的研究结果表明，蟾蜍的入侵已经改变了这种先天捕食者种群内的认知表型，这一变化可能会对其他物种产生实质性影响。

重要性声明

许多关于生物入侵影响的研究都集中于入侵者对本地分类单元数量的数值影响，而忽略了其他类型的影响。殖民地分类单元还可以对本地物种的行为特征进行选择，随着本地分类单元适应入侵者，行为发生转变。这种行为上的变化不仅本身很有趣，而且因为这种变化（特别是在尖锐掠食者中）可能会影响食物网中的其他分类单元。重要的是，这种变化的性质和程度可能会在入侵后随时间变化。