Abstract

The Novel Weapons Hypothesis postulates that the release of allelochemicals by alien plants can inhibit the growth of evolutionary naïve native plants. On the other hand, when species share a recent evolutionary history, recognition of phytochemicals from neighboring plants can have adaptive value by providing cues to signal suitable conditions conducive to establishment. This has been termed the Biochemical Recognition Hypothesis. We explored these two hypotheses by conducting germination experiments in South Africa and Spain and a growth experiment in South Africa, using invasive Australian acacias and native species from each region. The experiments exposed seeds of the selected recipient species to leachates collected under acacias, nearby uninvaded vegetation, or distilled water. We then measured total germination, and above and below ground biomass in the growth experiment. Our results did not support the Novel Weapons Hypothesis, but instead we found some leachates collected under acacias and uninvaded areas to stimulate the germination and early growth of some of our selected acacias and native species. Such effects occurred both at the intra- and interspecific level. In general, interspecific stimulatory effects between invasive acacias occurred irrespective of whether they had overlapping native ranges in Australia. We also found leachates from uninvaded areas in South Africa to have stimulatory effects on one invasive acacia and one native species. Hence, our results support the Biochemical Recognition Hypothesis, suggesting that chemically-induced signals may facilitate acacia establishment in sites that have already been transformed by acacias.

中文翻译：

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没有新武器的证据：生化识别调节本地物种和入侵相思的早期个体发育过程

摘要

新型武器假说假设外来植物释放化感物质会抑制进化的天然原生植物的生长。另一方面，当物种共享最近的进化史时，通过提供提示信号以告知有利于建立条件的线索，从邻近植物中识别植物化学物质可能具有适应性价值。这被称为生化识别假说。我们通过使用入侵性澳大利亚洋槐和每个地区的本地树种在南非和西班牙进行发芽实验以及在南非进行生长实验，探索了这两个假设。实验将所选受体物种的种子暴露于在洋槐，附近未入侵植被或蒸馏水下收集的沥滤液。然后我们测量了总发芽量 生长实验中地上和地下的生物量。我们的结果不支持新颖武器假说，但相反，我们发现在相思树和未入侵区域下收集了一些渗滤液，以刺激某些我们所选择的相思树和本地物种的发芽和早期生长。这样的影响发生在种内和种间水平上。通常，侵入性相思之间存在种间刺激作用，无论它们在澳大利亚是否具有重叠的自然范围。我们还发现，来自南非未入侵地区的渗滤液对一种入侵相思和一种本土物种具有刺激作用。因此，我们的结果支持生化识别假说，表明化学诱导的信号可能有助于在已经被阿拉伯胶转化的部位中建立阿拉伯胶。