School of the Environment, University of Technology Sydney, , Broadway, New South Wales 2007, Australia.
Biol Lett. 2014 Feb 26;10(2):20131014. doi: 10.1098/rsbl.2013.1014. Print 2014 Feb.
Plasticity or evolution in behavioural responses are key attributes of successful animal invasions. In northern Australia, the invasive cane toad (Rhinella marina) recently invaded semi-arid regions. Here, cane toads endure repeated daily bouts of severe desiccation and thermal stress during the long dry season (April-October). We investigated whether cane toads have shifted their ancestral nocturnal rehydration behaviour to one that exploits water resources during the day. Such a shift in hydration behaviour could increase the fitness of individual toads by reducing exposure to desiccation and thermal stress suffered during the day even within terrestrial shelters. We used a novel method (acoustic tags) to monitor the daily hydration behaviour of 20 toads at two artificial reservoirs on Camfield station, Northern Territory. Remarkably, cane toads visited reservoirs to rehydrate during daylight hours, with peaks in activity between 9.00 and 17.00. This diurnal pattern of rehydration activity contrasts with nocturnal rehydration behaviour exhibited by adult toads in their native geographical range and more mesic parts of Australia. Our results demonstrate that cane toads phase shift a key behaviour to survive in a harsh semi-arid landscape. Behavioural phase shifts have rarely been reported in invasive species but could facilitate ongoing invasion success.
行为反应的可塑性或进化是动物成功入侵的关键特征。在澳大利亚北部，入侵的甘蔗蟾蜍（Rhinella marina）最近入侵了半干旱地区。在这里，甘蔗蟾蜍在漫长的旱季（4 月至 10 月）中会经历反复的严重脱水和热应激。我们研究了甘蔗蟾蜍是否已经将其祖先的夜间补水行为转变为一种在白天利用水资源的行为。这种补水行为的转变可以通过减少白天在陆地避难所中遭受的脱水和热应激来提高个体蟾蜍的适应度。我们使用一种新的方法（声学标签）在北领地 Camfield 站的两个人工水库监测了 20 只蟾蜍的日常补水行为。值得注意的是，甘蔗蟾蜍在白天会去水库补水，活动高峰期在 9 点到 17 点之间。这种白天的补水活动模式与成年蟾蜍在其原生地理范围和澳大利亚更湿润地区表现出的夜间补水行为形成鲜明对比。我们的研究结果表明，甘蔗蟾蜍会改变关键行为以在恶劣的半干旱景观中生存。行为相移在入侵物种中很少有报道，但可能有助于其持续入侵成功。
