Willis Anthony J, Thomas Matthew B, Lawton John H
Leverhulme Unit for Population Biology and Biological Control, NERC Centre for Population Biology and CABI Bioscience, Imperial College at Silwood Park, Ascot, Berks, SL5 7PY, UK, , , , , , GB.
Oecologia. 1999 Sep;120(4):632-640. doi: 10.1007/s004420050899.
Blossey and Nötzold (1995) recently hypothesised that the increased vigour of certain invasive plant species has been at the expense of defences against natural enemies. A prediction of their evolution of increased competitive ability (EICA) hypothesis is that invasive genotypes are relatively poorly defended. We tested this prediction with herbivore bioassays and with direct quantification of plant secondary metabolites comparing non-indigenous genotypes of Lythrum salicaria L. (purple loosestrife) with indigenous forms. The herbivore bioassays revealed no significant intra-specific variation in herbivore resistance between indigenous and non-indigenous hosts. The phenolic content of L. salicaria leaves was significantly higher in indigenous genotypes, as predicted by the EICA hypothesis. The average phenolic content of leaves (regardless of their origin) was, however, low, implying that the role of plant phenolics in purple loosestrife anti-herbivore defence is probably limited. It is suggested that the EICA hypothesis, as tested in the current study, does not explain the increased vigour of L. salicaria in non-indigenous habitats.
布洛西和内措尔德（1995年）最近提出假说，认为某些入侵植物物种活力的增强是以牺牲对天敌的防御能力为代价的。他们的竞争能力增强进化（EICA）假说的一个预测是，入侵基因型的防御能力相对较差。我们通过食草动物生物测定以及直接定量植物次生代谢产物，将非本土基因型的千屈菜（Lythrum salicaria L.，即紫千屈菜）与本土类型进行比较，来检验这一预测。食草动物生物测定结果显示，本土和非本土宿主之间在对食草动物的抗性方面没有显著的种内差异。正如EICA假说所预测的，本土基因型的千屈菜叶片中酚类物质的含量显著更高。然而，叶片（无论其来源）的平均酚类物质含量较低，这意味着植物酚类物质在紫千屈菜抗食草动物防御中的作用可能有限。有人认为，在本研究中所检验的EICA假说并不能解释紫千屈菜在非本土生境中活力增强的现象。
