Menke S B, Fisher R N, Jetz W, Holway D A
Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093-0116, USA.
Ecology. 2007 Dec;88(12):3164-73. doi: 10.1890/07-0122.1.
Although the ecological success of introduced species hinges on biotic interactions and physical conditions, few experimental studies--especially on animals--have simultaneously investigated the relative importance of both types of factors. The lack of such research may stem from the common assumption that native and introduced species exhibit similar environmental tolerances. Here we combine experimental and spatial modeling approaches (1) to determine the relative importance of biotic and abiotic controls of Argentine ant (Linepithema humile) invasion success, (2) to examine how the importance of these factors changes with spatial scale in southern California (USA), and (3) to assess how Argentine ants differ from native ants in their environmental tolerances. A factorial field experiment that combined native ant removal with irrigation revealed that Argentine ants failed to invade any dry plots (even those lacking native ants) but readily invaded all moist plots. Native ants slowed the spread of Argentine ants into irrigated plots but did not prevent invasion. In areas without Argentine ants, native ant species showed variable responses to irrigation. At the landscape scale, Argentine ant occurrence was positively correlated with minimum winter temperature (but not precipitation), whereas native ant diversity increased with precipitation and was negatively correlated with minimum winter temperature. These results are of interest for several reasons. First, they demonstrate that fine-scale differences in the physical environment can eclipse biotic resistance from native competitors in determining community susceptibility to invasion. Second, our results illustrate surprising complexities with respect to how the abiotic factors limiting invasion can change with spatial scale, and third, how native and invasive species can differ in their responses to the physical environment. Idiosyncratic and scale-dependent processes complicate attempts to forecast where introduced species will occur and how their range limits may shift as a result of climate change.
尽管外来物种在生态上的成功取决于生物相互作用和物理条件，但很少有实验研究——尤其是针对动物的研究——同时调查这两类因素的相对重要性。缺乏此类研究可能源于一种普遍假设，即本地物种和外来物种表现出相似的环境耐受性。在此，我们结合实验和空间建模方法：（1）确定生物和非生物因素对阿根廷蚁（Linepithema humile）入侵成功的相对重要性；（2）研究在美国南加州这些因素的重要性如何随空间尺度变化；（3）评估阿根廷蚁与本地蚂蚁在环境耐受性方面的差异。一项将去除本地蚂蚁与灌溉相结合的析因田间实验表明，阿根廷蚁无法侵入任何干燥地块（即使那些没有本地蚂蚁的地块），但能轻易侵入所有潮湿地块。本地蚂蚁减缓了阿根廷蚁向灌溉地块的扩散，但并未阻止入侵。在没有阿根廷蚁的地区，本地蚂蚁物种对灌溉表现出不同的反应。在景观尺度上，阿根廷蚁的出现与冬季最低温度呈正相关（但与降水量无关），而本地蚂蚁的多样性随降水量增加，且与冬季最低温度呈负相关。这些结果之所以令人感兴趣有几个原因。首先，它们表明在决定群落对入侵的易感性方面，物理环境的细粒度差异可能会使来自本地竞争者的生物抗性黯然失色。其次，我们的结果说明了在限制入侵的非生物因素如何随空间尺度变化方面存在惊人的复杂性，第三，说明了本地物种和入侵物种对物理环境的反应可能存在差异。独特且依赖尺度的过程使得预测外来物种将出现在何处以及它们的分布范围可能如何因气候变化而变化变得复杂。
