Urban Mark C, Phillips Ben L, Skelly David K, Shine Richard
School of Forestry and Environmental Studies, Yale University, New Haven, CT 06511, USA.
Proc Biol Sci. 2007 Jun 7;274(1616):1413-9. doi: 10.1098/rspb.2007.0114.
Invasive species threaten biological diversity throughout the world. Understanding the dynamics of their spread is critical to mitigating this threat. In Australia, efforts are underway to control the invasive cane toad (Chaunus [Bufo] marinus). Range models based on their native bioclimatic envelope suggest that the cane toad is nearing the end of its invasion phase. However, such models assume a conserved niche between native and invaded regions and the absence of evolution to novel habitats. Here, we develop a dynamically updated statistical model to predict the growing extent of cane toad range based on their current distribution in Australia. Results demonstrate that Australian cane toads may already have the ability to spread across an area that almost doubles their current range and that triples projections based on their native distribution. Most of the expansion in suitable habitat area has occurred in the last decade and in regions characterized by high temperatures. Increasing use of extreme habitats may indicate that novel ecological conditions have facilitated a broader realized niche or that toad populations at the invasion front have evolved greater tolerance to extreme abiotic conditions. Rapid evolution to novel habitats combined with ecological release from native enemies may explain why some species become highly successful global invaders. Predicting species ranges following invasion or climate change may often require dynamically updated range models that incorporate a broader realization of niches in the absence of natural enemies and evolution in response to novel habitats.
入侵物种威胁着全球的生物多样性。了解其扩散动态对于减轻这一威胁至关重要。在澳大利亚,人们正在努力控制入侵的蔗蟾蜍(海蟾蜍,Chaunus [Bufo] marinus)。基于其原生生物气候包络的分布模型表明,蔗蟾蜍的入侵阶段即将结束。然而,此类模型假定原生区域和入侵区域之间的生态位是保守的,并且不存在向新栖息地的进化。在此,我们开发了一种动态更新的统计模型,以根据蔗蟾蜍目前在澳大利亚的分布来预测其不断扩大的分布范围。结果表明,澳大利亚的蔗蟾蜍可能已经有能力扩散到一个面积几乎是其当前分布范围两倍的区域,并且是基于其原生分布预测范围的三倍。适宜栖息地面积的大部分扩张发生在过去十年以及高温地区。对极端栖息地的利用增加可能表明新的生态条件促成了更广泛的实际生态位,或者入侵前沿的蟾蜍种群已经进化出对极端非生物条件更强的耐受性。向新栖息地的快速进化加上摆脱了原生天敌的生态释放,可能解释了为什么有些物种会成为全球范围内极为成功的入侵者。预测入侵或气候变化后的物种分布范围,可能通常需要动态更新的分布模型,这些模型要在没有天敌以及不存在针对新栖息地进化的情况下,纳入对生态位更广泛的认识。