Grainger Tess Nahanni, Rego Adam Ivan, Gilbert Benjamin
Am Nat. 2018 Feb;191(2):197-209. doi: 10.1086/695688. Epub 2017 Dec 19.
The order of species arrival at a site can determine the outcome of competitive interactions when early arrivers alter the environment or deplete shared resources. These priority effects are predicted to be stronger at high temperatures, as higher vital rates caused by warming allow early arrivers to more rapidly impact a shared environment. We tested this prediction using a pair of congeneric aphid species that specialize on milkweed plants. We manipulated temperature and arrival order of the two aphid species and measured aphid population dynamics and milkweed survival and defensive traits. We found that warming increased the impact of aphids on the quantity and quality of milkweed, which amplified the importance of priority effects by increasing the competitive exclusion of the inferior competitor when it arrived late. Warming also enhanced interspecific differences in dispersal, which could alter relative arrival times at a regional scale. Our experiment provides a first link between temperature-dependent trophic interactions, priority effects, and dispersal. This study suggests that the indirect and cascading effects of temperature observed here may be important determinants of diversity in the temporally and spatially complex landscapes that characterize ecological communities.
当早期到达者改变环境或耗尽共享资源时，物种到达某一地点的顺序可以决定竞争相互作用的结果。这些优先效应预计在高温下会更强，因为变暖导致的更高生命率使早期到达者能够更快地影响共享环境。我们使用一对专门以马利筋植物为食的同属蚜虫物种对这一预测进行了测试。我们控制了两种蚜虫物种的温度和到达顺序，并测量了蚜虫种群动态以及马利筋的存活和防御特征。我们发现，变暖增加了蚜虫对马利筋数量和质量的影响，当劣势竞争者晚到达时，这通过增加对它的竞争排斥放大了优先效应的重要性。变暖还增强了种间扩散差异，这可能会在区域尺度上改变相对到达时间。我们的实验首次建立了温度依赖的营养相互作用、优先效应和扩散之间的联系。这项研究表明，此处观察到的温度的间接和级联效应可能是生态群落所特有的时空复杂景观中多样性的重要决定因素。
