IMARES, P.O. Box 77, 4400 AB Yerseke, The Netherlands.
J Theor Biol. 2012 Sep 7;308:36-44. doi: 10.1016/j.jtbi.2012.05.017. Epub 2012 May 31.
An organism can be defined as omnivorous if it feeds on more than one trophic level. Omnivory is present in many ecosystems and multiple omnivorous species can coexist in the same ecosystem. How coexisting omnivores are able to avoid competitive exclusion is very much an open question. In this paper we analyze a model of a community consisting of two omnivorous predators and a basal resource. The population of both predators is explicitly structured into juveniles and adults, of which juveniles only feed on basal resource and adults feed on a varied proportion of basal resource and juveniles of the other population. We thereby separate the omnivorous roles (competitor for basal resource and predator of competitors) over life history. We show in this study that persistence of multiple omnivorous predators is possible when predators differ in adult diets. In this case, coexistence occurs because community dynamics force one of the model species to act as a predator and the other to act as a consumer. We conclude that separation of omnivorous roles over life history not only offers an explanation on why systems with omnivory can persist, but also how multiple omnivores can coexist at the same trophic levels of those systems.
如果一种生物以超过一个营养级的生物为食，就可以将其定义为杂食性生物。在许多生态系统中都存在杂食性，并且在同一个生态系统中可以共存多种杂食性物种。共存的杂食动物如何避免竞争排斥是一个非常开放的问题。在本文中，我们分析了一个由两种杂食性捕食者和一个基础资源组成的群落模型。两个捕食者的种群都明确地分为幼体和成年个体，其中幼体只以基础资源为食，而成年个体则以不同比例的基础资源和其他种群的幼体为食。这样，我们就在整个生命史中分离了杂食性的角色（对基础资源的竞争和对竞争者的捕食）。本研究表明，当捕食者在成年期的饮食不同时，多个杂食性捕食者的持续存在是可能的。在这种情况下，共存是因为群落动态迫使其中一种模型物种充当捕食者，而另一种则充当消费者。我们得出结论，在整个生命史中分离杂食性角色不仅提供了一个解释，说明为什么具有杂食性的系统能够持续存在，还说明了为什么多个杂食动物可以在同一营养级共存。
