了解物种之间的互动怎样帮助维护物种多样性，是生态学中的一个基础性问题。Peter Chesson 和 Jessica Kuang提出的新的理论结果，突出显示了捕食与竞争在决定共存中所扮演的相互独立的角色。他们发现，每个机制都能通过与特定物种的多样关系来促进多样性，或通过让某种物种彼此之间进行竞争的狭隘关系来限制多样性。每个机制也都能减小另一个机制的影响，或与另一个机制协同作用来促进多样性，由具体情况来决定。（生物谷Bioon.com）
生物谷推荐原始出处：
Nature 456, 235-238 (13 November 2008) | doi:10.1038/nature07248
The interaction between predation and competition
Peter Chesson & Jessica J. Kuang
Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721, USA
Competition and predation are the most heavily investigated species interactions in ecology, dominating studies of species diversity maintenance. However, these two interactions are most commonly viewed highly asymmetrically. Competition for resources is seen as the primary interaction limiting diversity, with predation modifying what competition does1, although theoretical models have long supported diverse views1, 2, 3, 4, 5. Here we show, using a comprehensive three-trophic-level model, that competition and predation should be viewed symmetrically: these two interactions are equally able to either limit or promote diversity. Diversity maintenance requires within-species density feedback loops to be stronger than between-species feedback loops. We quantify the contributions of predation and competition to these loops in a simple, interpretable form, showing their equivalent potential to strengthen or weaken diversity maintenance. Moreover, we show that competition and predation can undermine each other, with the tendency of the stronger interaction to promote or limit diversity prevailing. The past failure to appreciate the symmetrical effects and interactions of competition and predation has unduly restricted diversity maintenance studies. A multitrophic perspective should be adopted to examine a greater variety of possible effects of predation than generally considered in the past. Conservation and management strategies need to be much more concerned with the implications of changes in the strengths of trophic interactions.
