Species interactions and a chain of indirect effects driven by reduced precipitation
Species interactions and a chain of indirect effects driven by reduced precipitation
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DOI：
10.1890/13-0044.1
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发表时间：
2014-02-01
期刊：
影响因子：
4.8
通讯作者：
Ives, Anthony R.
中科院分区：
文献类型：
--
作者：
Barton, Brandon T.;Ives, Anthony R.
气候变化可以通过改变群落内物种之间的相互作用直接或间接地影响物种。这些间接的影响可以通过一个社区产生分歧，影响到许多物种，包括一些可能没有直接受到扰动的影响。识别这些间接影响链是困难的，大多数研究只关注两三个物种的间接影响。在这里，我们使用析因田间实验来证明，降水影响斑点蚜虫通过一个复杂的链间接的相互作用，介导的其他食草动物和通才捕食者。我们实验模拟干旱，这减少了苜蓿植物的含水量。苜蓿水分胁迫对苜蓿蚜没有直接影响，但降低了另一种常见苜蓿害虫豌豆蚜的种群增长率。由于瓢虫捕食者被吸引到高密度豌豆蚜虫，捕食者密度较低的干旱处理。因此，斑点蚜虫密度释放自上而下的控制（明显的竞争）在干旱处理，并达到密度比斑点蚜虫在环境处理高豌豆蚜虫密度的三倍。因此，干旱影响斑蚜的相互作用链：干旱苜蓿豌豆蚜捕食斑蚜。这一结果说明了气候变化的间接影响可能通过社区的漫长路径，以及社区一级的实验在确定气候变化的净影响方面的重要性。
Climate change can affect species directly and indirectly by altering interactions between species within communities. These indirect effects can ramify through a community and affect many species, including some that may not have been directly affected by the perturbation. Identifying these chains of indirect effects is difficult, and most studies only follow indirect effects across two or three species. Here, we use a factorial field experiment to demonstrate that precipitation affects spotted aphids through a complex chain of indirect interactions that are mediated by other herbivores and a generalist predator. We experimentally simulated drought, which reduced water content in alfalfa plants. While water stress in alfalfa had no direct effect on spotted aphids, it lowered the population growth rate of pea aphids, another common alfalfa pest. Because ladybeetle predators were attracted to high pea aphid densities, predator densities were lower in drought treatments. Consequently, spotted aphid densities were released from top-down control (apparent competition) in drought treatments and reached densities three times higher than spotted aphids in ambient treatments with high pea aphid densities. Thus, drought affected spotted aphids in the interaction chain: drought alfalfa pea aphids predators spotted aphids. This result illustrates the lengthy path that indirect effects of climate change may take through a community, as well as the importance of community-level experiments in determining the net effect of climate change.