Gianoli Ernesto, Salgado-Luarte Cristian
Departamento de Biología, Universidad de La Serena, Casilla 554 La Serena, Chile
Departamento de Botánica, Universidad de Concepción, Concepción, Chile.
Biol Lett. 2017 May;13(5). doi: 10.1098/rsbl.2017.0120.
The resource availability hypothesis (RAH), the most successful theory explaining plant defence patterns, predicts that defence investment is related to the relative growth rate (RGR) of plant species, which is associated with habitat quality. Thus, fast-growing species should show lower resistance than slow-growing species, which would lead fast growers to sustain higher herbivory rates, but the fitness consequences of herbivory would be greater for slow growers. The latter is often assumed but rarely tested. In a temperate rainforest, we tested the expected pattern of tolerance to herbivory derived from the RAH: that fast-growing species should be more tolerant than slow-growing species. We also evaluated whether other plant features covary with RGR (leaf lifespan, shade tolerance and leaf toughness) and thus could also contribute to the patterns of tolerance to herbivory. As expected, seedlings from tree species with higher RGR showed greater tolerance to herbivory. Among the three plant features included, only leaf lifespan showed a significant association with RGR, but RGR was the best predictor of tolerance. We argue that plant tolerance to herbivory must be evaluated to properly verify the assumptions of the RAH.
资源可用性假说（RAH）是解释植物防御模式最成功的理论，它预测防御投入与植物物种的相对生长速率（RGR）相关，而相对生长速率又与栖息地质量有关。因此，快速生长的物种应比缓慢生长的物种表现出更低的抗性，这将导致快速生长的物种遭受更高的食草动物啃食率，但食草动物啃食对缓慢生长的物种的适合度影响会更大。后者常被假定但很少得到验证。在一个温带雨林中，我们测试了从资源可用性假说推导出来的对食草动物耐受性的预期模式：即快速生长的物种应该比缓慢生长的物种更具耐受性。我们还评估了其他植物特征是否与相对生长速率共同变化（叶片寿命、耐荫性和叶片韧性），因此也可能对食草动物耐受性模式有贡献。正如预期的那样，相对生长速率较高的树种的幼苗对食草动物表现出更大的耐受性。在所纳入的三个植物特征中，只有叶片寿命与相对生长速率有显著关联，但相对生长速率是耐受性的最佳预测指标。我们认为，必须评估植物对食草动物的耐受性，以正确验证资源可用性假说的假设。
