Bio-Protection Research Centre, Lincoln University, PO Box 85084, Lincoln 7647, New Zealand
Bio-Protection Research Centre, Lincoln University, PO Box 85084, Lincoln 7647, New Zealand.
AoB Plants. 2016 Apr 16;8. doi: 10.1093/aobpla/plw016. Print 2016.
The evolution of increased competitive ability (EICA) hypothesis could explain why some introduced plant species perform better outside their native ranges. The EICA hypothesis proposes that introduced plants escape specialist pathogens or herbivores leading to selection for resources to be reallocated away from defence and towards greater competitive ability. We tested the hypothesis that escape from soil-borne enemies has led to increased competitive ability in three non-agriculturalTrifolium(Fabaceae) species native to Europe that were introduced to New Zealand in the 19th century.Trifoliumperformance is intimately tied to rhizosphere biota. Thus, we grew plants from one introduced (New Zealand) and two native (Spain and the UK) provenances for each of three species in pots inoculated with soil microbiota collected from the rhizosphere beneath conspecifics in the introduced and native ranges. Plants were grown singly and in competition with conspecifics from a different provenance in order to compare competitive ability in the presence of different microbial communities. In contrast to the predictions of the EICA hypothesis, we found no difference in the competitive ability of introduced and native provenances when grown with soil microbiota from either the native or introduced range. Although plants from introduced provenances of two species grew more slowly than native provenances in native-range soils, as predicted by the EICA hypothesis, plants from the introduced provenance were no less competitive than native conspecifics. Overall, the growth rate of plants grown singly was a poor predictor of their competitive ability, highlighting the importance of directly quantifying plant performance in competitive scenarios, rather than relying on surrogate measures such as growth rate.
竞争能力增强进化假说（EICA）可以解释为什么一些引入的植物物种在其原生范围之外表现更好。EICA 假说提出，引入的植物逃避了专门的病原体或食草动物，从而选择将资源重新分配到防御之外，以提高竞争能力。我们测试了这样一个假说，即逃避土壤传播的敌人导致了三种原产于欧洲的非农业三叶草（豆科）物种在 19 世纪引入新西兰后竞争能力的增强。三叶草的表现与根际生物群密切相关。因此，我们在花盆中种植了来自三个物种的一个引入（新西兰）和两个本地（西班牙和英国）种源的植物，这些花盆中接种了从引入和本地范围下同种植物根际收集的土壤微生物群。植物单独生长，并与来自不同种源的同种植物竞争，以比较在不同微生物群落存在下的竞争能力。与 EICA 假说的预测相反，当与来自原生或引入范围的根际土壤微生物群一起生长时，我们没有发现引入和本地种源的竞争能力有差异。尽管两种物种的引入种源植物在原生土壤中比本地种源植物生长缓慢，这符合 EICA 假说的预测，但引入种源的植物并不比本地同种植物竞争力差。总的来说，单独生长的植物的生长速度是其竞争能力的一个很差的预测指标，这强调了在竞争情景中直接量化植物表现的重要性，而不是依赖于生长速度等替代指标。
