CIBUS, Campus Sur, Universidade de Santiago, 15782, Santiago de Compostela, Spain.
Department of Functional Biology, Area of Ecology, Faculty of Biology, CRETUS Inst., Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
BMC Ecol Evol. 2021 Apr 28;21(1):69. doi: 10.1186/s12862-021-01785-x.
Although the immediate consequences of biological invasions on ecosystems and conservation have been widely studied, the long-term effects remain unclear. Invaders can either cause the extinction of native species or become integrated in the new ecosystems, thus increasing the diversity of these ecosystems and the services that they provide. The final balance of invasions will depend on how the invaders and native plants co-evolve. For a better understanding of such co-evolution, case studies that consider the changes that occur in both invasive and native species long after the introduction of the invader are especially valuable. In this work, we studied the ecological consequences of the more than one century old invasion of NW Iberia by the African plant Carpobrotus edulis. We conducted a common garden experiment to compare the reciprocal effects of competition between Carpobrotus plants from the invaded area or from the native African range and two native Iberian plant species (Artemisia crithmifolia and Helichrysum picardii) from populations exposed or unexposed to the invader.
Exposure of H. picardii populations to C. edulis increased their capacity to repress the growth of Carpobrotus. The repression specifically affected the Carpobrotus from the invader populations, not those from the African native area. No effects of exposition were detected in the case of A. crithmifolia. C. edulis plants from the invader populations had higher growth than plants from the species' African area of origin.
We found that adaptive responses of natives to invaders can occur in the long term, but we only found evidence for adaptive responses in one of the two species studied. This might be explained by known differences between the two species in the structure of genetic variance and gene flow between subpopulations. The overall changes observed in the invader Carpobrotus are consistent with adaptation after invasion.
尽管生物入侵对生态系统和保护的直接后果已经得到了广泛的研究，但长期影响仍不清楚。入侵者要么导致本地物种灭绝，要么成为新生态系统的一部分，从而增加了这些生态系统的多样性和它们所提供的服务。入侵的最终平衡将取决于入侵者和本地植物如何共同进化。为了更好地理解这种共同进化，考虑到入侵后很长一段时间内入侵物种和本地物种发生的变化的案例研究特别有价值。在这项工作中，我们研究了非洲植物Carpobrotus edulis 一个多世纪以来对西北伊比利亚的入侵所带来的生态后果。我们进行了一个共同花园实验，以比较来自入侵地区或来自非洲本土范围的Carpobrotus 植物与两种来自暴露或未暴露于入侵者的伊比利亚本地植物（Artemisia crithmifolia 和 Helichrysum picardii）之间竞争的相互影响。
暴露于 C. edulis 的 H. picardii 种群增加了抑制 Carpobrotus 生长的能力。抑制作用专门影响来自入侵种群的 Carpobrotus，而不影响来自非洲本土地区的 Carpobrotus。在 A. crithmifolia 的情况下没有检测到暴露的影响。来自入侵种群的 C. edulis 植物的生长高于该物种非洲起源地区的植物。
我们发现，本地植物对入侵者的适应性反应可能会在长期内发生，但我们只在研究的两个物种之一中发现了适应性反应的证据。这可能是由于两个物种之间遗传方差和亚种群间基因流的结构已知存在差异。在入侵的 Carpobrotus 中观察到的总体变化与入侵后的适应一致。
