标题： 杂食性既可以增强也可以减弱食物网中的扰动 显示英文标题

标题： Omnivory can both enhance and dampen perturbations in food webs

摘要： 我们研究了在存在和不存在自相互作用及杂食性的情况下，扰动如何在食物链中上下传播。扰动的来源是某一营养级死亡率的改变，扰动的度量是扰动后和未扰动的稳态种群之间的差异。对于具有线性功能性反应的Lotka-Volterra食物链，我们通过分析表明，种内竞争和同营养级捕食既可以减弱也可以增强扰动的传播，从而稳定或不稳定食物网。这种影响的方向取决于扰动源的位置以及额外的竞争和捕食链接的位置。这些结论通过数值方法在具有更现实的II型功能性反应的食物链中得到了验证。我们的结果支持了关于种内竞争和杂食性对营养系统稳定性影响的长期争论中双方的观点。 显示英文摘要

摘要： We investigate how perturbations propagate up and down a food chain with and without self-interaction and omnivory. A source of perturbation is a shift in death rate of a trophic level, and the measure of perturbation is the difference between the perturbed and unperturbed steady state populations. For Lotka-Volterra food chains with linear functional response, we show analytically that both intraspecific competition and intraguild predation can either dampen or enhance the propagation of perturbations, thus stabilizing or destabilizing the food web. The direction of the effect depend on the position of the source of perturbation, as well as on the position of the additional competitive and predatory links . These conclusions are confirmed numerically for a food chain with more realistic Type-II functional response. Our results support the positions of both sides in the long-standing debate on the effect of intraspecific competition and omnivory on the stability of trophic systems.