Abstract The adaptive nature of invasive species facilitates their survival in conditions that differ markedly from their native range. Behavioral changes in invasive populations are poorly explored but offer a wide potential when combined with physiological traits. For amphibians invading xeric habitats, finding water is important to function optimally and avoid dehydration. The water-finding hypothesis postulates that survival can be enhanced through the increased behavioral ability to find water. We tested the water-finding hypothesis in guttural toads ( Sclerophrys gutturalis ) from their native range and an invasive population. Additionally, we tested if artificially elevated corticosterone levels, which increase during dehydration, affect behavioral traits linked to water balance. In a labyrinth experiment, we observed the toads’ ability to find water in different hydration states (100%, 90%, and 80%). We found that individuals from the invasive population took longer to engage in water-searching behavior and spent more time close to the water source after finding it. Toads from the invasive population were also more active, and at 90% hydration, their attempts to find water increased. Moreover, artificially increasing corticosterone in fully hydrated invasive toads increased water-finding success. Our experiments demonstrated that invasive toads show water-conservation behaviors that can optimize water balance and might facilitate survival in an invaded xeric environment. Additionally, we suggest a link between elevated corticosterone levels and water-finding success. Our results lend support to the importance of behavior in successful invasions and the modulation of water-finding behavior by corticosterone. Significant statement Invasion success is associated with behavioral and physiological adaptations of invasive species. For anuran species invading xeric habitats, the ability to find water is an important behavioral trait. Using a labyrinth experiment and toads ( Sclerophrys gutturalis ) dehydrated at different levels, we observed that individuals invading a hydric challenging habitat showed advantageous water-conservation behaviors (e.g., taking longer to engage in water-searching behavior and spent more time close to the water source after finding it) compared to toads from the native range. Transdermal treatment with corticosterone, a hormone that increases its plasma concentrations under dehydration, increased success of finding water in 100% hydrated animals. Our results indicate that, compared to the native population, invasive toads display water-conservation behaviors that might improve survival rates in a novel xeric environment and that experimental corticosterone elevation modulates this water-finding behavior.

中文翻译：

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脱水的挑战导致侵入性蟾蜍的行为转变

摘要 入侵物种的适应性有利于它们在与原生范围明显不同的条件下生存。入侵种群的行为变化很少被探索，但与生理特征相结合时提供了广泛的潜力。对于入侵干旱栖息地的两栖动物来说，寻找水对于最佳运作和避免脱水很重要。寻水假说假定通过增加寻找水的行为能力可以提高生存率。我们在原产地和入侵种群的喉蟾蜍 (Sclerophrys gutturalis) 中测试了寻水假说。此外，我们测试了人为升高的皮质酮水平（在脱水期间会增加）是否会影响与水平衡相关的行为特征。在迷宫实验中，我们观察到蟾蜍在不同水合状态（100%、90% 和 80%）下寻找水的能力。我们发现，来自入侵种群的个体进行寻水行为的时间更长，并且在找到水源后花费更多时间靠近水源。来自入侵种群的蟾蜍也更加活跃，在 90% 的水合作用时，它们寻找水的尝试增加了。此外，在完全水合的侵入性蟾蜍中人为增加皮质酮增加了寻找水的成功率。我们的实验表明，侵入性蟾蜍表现出节水行为，可以优化水平衡，并可能促进在侵入性干旱环境中的生存。此外，我们建议皮质酮水平升高与寻水成功之间存在联系。我们的结果支持行为在成功入侵中的重要性以及皮质酮对找水行为的调节。重要声明 入侵成功与入侵物种的行为和生理适应有关。对于入侵干旱栖息地的无尾类物种，寻找水源的能力是一个重要的行为特征。使用迷宫实验和蟾蜍 (Sclerophrys gutturalis ) 在不同程度脱水，我们观察到入侵具有挑战性的富氢栖息地的个体表现出有利的节水行为（例如，花更长时间从事寻水行为，并在靠近水的地方花费更多时间）找到它后的来源）与本地范围内的蟾蜍相比。用皮质酮进行透皮治疗，皮质酮是一种在脱水时增加血浆浓度的激素，提高了在 100% 水合动物中找到水的成功率。我们的结果表明，与本地种群相比，侵入性蟾蜍表现出节水行为，这可能会提高在新的干旱环境中的存活率，并且实验性皮质酮升高会调节这种寻水行为。