Kuang Jessica J, Chesson Peter
Department of Mathematics, University of California, Davis, California 95616, USA.
Am Nat. 2008 Mar;171(3):E119-33. doi: 10.1086/527484.
We investigate the interacting effects of predation and competition on species coexistence in a model of seasonally recruiting species in a constant environment. For these species, life-history parameters, such as maximum productivity and survival, have important roles in fluctuation-dependent species coexistence in that they introduce nonlinearities into population growth rates and cause endogenous population fluctuations, which can activate the coexistence mechanism termed "relative nonlinearity." Under this mechanism, different species must differ in the nonlinearities of their growth rates and must make different contributions to fluctuations in competition and predation. Both of these features can result from life-history trade-offs associated with seasonal recruitment. Coexistence by relative nonlinearity can occur with or without predation. However, predation can undermine coexistence. It does this by reducing variance contrasts between species. However, when competition is not sufficient to cause endogenous population fluctuations, predation can enable fluctuation-dependent coexistence by destabilizing the equilibrium. This model also reproduces the classic finding that coexistence can occur with selective predation provided that it causes a trade-off between competition and predation. Our model is formulated for competition between annual plant species subject to seed predation, but it also applies to perennial communities where competition and predation limit recruitment to the adult population.
我们在一个恒定环境中季节性招募物种的模型中，研究捕食和竞争对物种共存的相互作用影响。对于这些物种而言，诸如最大生产力和存活率等生活史参数，在依赖波动的物种共存中起着重要作用，因为它们会给种群增长率引入非线性，并导致内源性种群波动，这能够激活被称为“相对非线性”的共存机制。在这种机制下，不同物种的增长率非线性必须存在差异，并且在竞争和捕食的波动中必须做出不同贡献。这两个特征都可能源于与季节性招募相关的生活史权衡。相对非线性导致的共存可以在有或没有捕食的情况下发生。然而，捕食可能会破坏共存。它通过降低物种间的方差差异来做到这一点。然而，当竞争不足以引起内源性种群波动时，捕食可以通过使平衡不稳定来实现依赖波动的共存。该模型还重现了一个经典发现，即如果选择性捕食能够在竞争和捕食之间造成权衡，那么共存就可能发生。我们的模型是针对受种子捕食影响的一年生植物物种之间的竞争构建的，但它也适用于竞争和捕食限制成年种群补充的多年生群落。
