Data from: An invasive herbivore structures plant competitive dynamics

Species interactions are central to our understanding of ecological communities, but may change rapidly with the introduction of invasive species. Invasive species can alter species interactions and community dynamics directly by having larger detrimental effects on some species than others, or indirectly by changing the ways in which native species compete among themselves. We tested the direct and indirect effects of an invasive aphid herbivore on a native aphid species and two host milkweed species. The invasive aphid caused a 10-fold decrease in native aphid populations, and a 30% increase in plant mortality (direct effects). The invasive aphid also increased the strength of interspecific competition between the two native plant hosts (indirect effects). By investigating the role that indirect effects play in shaping species interactions in native communities, our study highlights an understudied component of species invasions.

物种互作是理解生态群落的核心环节，但入侵物种的引入可使其发生快速改变。入侵物种可通过直接或间接途径改变物种互作与群落动态：直接途径表现为对部分物种的有害影响强于其他物种；间接途径则体现为改变本土物种间的种内竞争方式。本研究针对一种入侵性植食性蚜虫（invasive aphid herbivore），探究其对一种本土蚜虫及两种寄主乳草（milkweed）物种的直接与间接效应。实验结果表明，该入侵蚜虫可使本土蚜虫种群数量下降10倍，并导致植物死亡率升高30%，此为直接作用效应。此外，该入侵蚜虫还增强了两种本土寄主植物间的种间竞争强度，此为间接作用效应。本研究通过探究间接作用在塑造本土群落物种互作中的作用，揭示了物种入侵研究中尚未得到充分关注的一个方面。