University of Guelph, Guelph, Ontario N1G 2W1, Canada.
Am Nat. 2012 Jan;179(1):22-37. doi: 10.1086/663191. Epub 2011 Nov 30.
Despite attempts at reconciliation, the role of omnivory in food web stability remains unclear. Here we develop a novel community matrix approach that is analogous to the bifurcation method of modular food web theory to show that the stability of omnivorous food chains depends critically on interaction strength. We find that there are only six possible ways that omnivorous interaction strengths can influence the stability of linear food chains. The results from these six cases suggest that: (1) strong omnivory is always destabilizing, (2) stabilization by weak to intermediate omnivorous interaction strengths dominates the set of possible stability responses, and, (3) omnivory can be occasionally strictly destabilizing or intermittently destabilizing. We then revisit the classical results of Pimm and Lawton to show that although their parameterization tends to produce a low percentage of stable omnivorous webs, the same parameterization shows strong theoretical support for the weak interaction effect. Finally, we end by arguing that our current empirical knowledge of omnivory resonates with this general theory.
尽管人们试图进行调和，但杂食性在食物网稳定性中的作用仍不清楚。在这里，我们开发了一种新颖的群落矩阵方法，该方法类似于模块化食物网理论的分岔方法，以表明杂食性食物链的稳定性取决于相互作用强度。我们发现，杂食性相互作用强度可能影响线性食物链稳定性的方式只有六种。这六种情况下的结果表明：（1）强杂食性总是不稳定的，（2）弱到中等杂食性相互作用强度的稳定作用占主导地位，（3）杂食性偶尔可能是严格不稳定的或间歇性不稳定的。然后，我们重新审视 Pimm 和 Lawton 的经典结果，表明尽管他们的参数化倾向于产生低比例的稳定杂食性网络，但相同的参数化对弱相互作用效应具有很强的理论支持。最后，我们认为，我们目前对杂食性的经验知识与这一普遍理论相吻合。
