Ingram Travis, Harmon Luke J, Shurin Jonathan B
Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
Am Nat. 2009 Jul;174(1):56-67. doi: 10.1086/599301.
The features that govern the stability and persistence of species interaction networks, such as food webs, remain elusive, but recent work suggests that the distribution and strength of trophic links play an important role. Potential omnivory-stability relationships have been investigated and debated extensively, but we still have a relatively poor understanding of how levels of omnivory relate to the stability of diverse food webs. Here, we use an evolutionary assembly model to investigate how different trade-offs in resource use influence both food web structure and dynamic stability during the assembly process. We build on a previous model by allowing speciation along with the evolution of two traits: body size and feeding-niche width. Across a wide range of conditions, the level of omnivory in a food web is positively related to its dynamic instability (variability and species turnover). Parameter values favoring omnivory also allow a wider range of phenotypes to invade, often displacing existing species. This high species turnover leaves signatures in reconstructed phylogenies, with shorter branches connecting extant species in more omnivorous food webs. Our findings suggest that features of the environment may influence both trophic structure and dynamic stability, leading to emergent omnivory-stability relationships.
诸如食物网等决定物种相互作用网络稳定性和持久性的特征仍然难以捉摸，但最近的研究表明，营养联系的分布和强度起着重要作用。潜在的杂食性与稳定性的关系已得到广泛研究和讨论，但我们对杂食性水平如何与多样化食物网的稳定性相关联仍了解相对较少。在此，我们使用一个进化组装模型来研究资源利用中的不同权衡如何在组装过程中影响食物网结构和动态稳定性。我们在之前的模型基础上进行构建，允许物种形成以及两个性状的进化：体型和取食生态位宽度。在广泛的条件下，食物网中的杂食性水平与其动态不稳定性（变异性和物种更替）呈正相关。有利于杂食性的参数值也允许更广泛的表型入侵，常常取代现有物种。这种高物种更替在重建的系统发育中留下印记，在杂食性更强的食物网中，连接现存物种的分支更短。我们的研究结果表明，环境特征可能会影响营养结构和动态稳定性，从而导致出现杂食性与稳定性的关系。
