Price Mary V, Mittler John E
Department of Biology, University of California, Riverside, CA 92521, USA.
J Theor Biol. 2003 Jul 21;223(2):215-31. doi: 10.1016/s0022-5193(03)00088-2.
Most models of resource competition assume that coexistence of consumers depends on tradeoffs in their abilities to exploit shared resources along dimensions of environmental heterogeneity generated by factors external to the consumers. However, consumers may create heterogeneity themselves by modifying resources that they do not immediately consume; such "resource processing" is predicted to allow coexistence if consumers vary in use of resources in primary vs. modified form. To explore whether external food storage (caching) represents a form of resource processing that contributes to observed patterns of species coexistence, we developed a biologically explicit simulation model of competition for a well-studied system, seed-eating desert heteromyid rodents. Here we present the model, compare competitive outcomes with and without inter-specific exchange of cached food, and describe population dynamics of coexisting competitors. The model predicts stable coexistence only when there is exchange of cached seeds via scavenging of caches left undefended by mortality or by pilferage of defended caches. Net interactions between coexisting consumers ranged from competition (10% of cases) to host-parasite (77%), commensalism (12%), and mutualism (1%). Population dynamics of coexisting consumers often showed strong periodicity and coupled synchronous or slightly lagged cycles, a possibility not previously anticipated for desert rodents occupying constant environments. Our model confirms that caching does represent a form of resource processing likely to play a significant role in the dynamics and diversity of communities of desert rodents and other caching animals.
大多数资源竞争模型假定，消费者的共存取决于它们在利用由消费者外部因素产生的环境异质性维度上的共享资源的能力方面的权衡。然而，消费者可能通过改变它们不会立即消耗的资源来创造异质性；如果消费者在初级形式与改变形式的资源使用上存在差异，那么这种“资源处理”预计会促进共存。为了探究外部食物储存（贮藏）是否代表一种有助于观察到的物种共存模式的资源处理形式，我们针对一个研究充分的系统——以种子为食的沙漠异鼠科啮齿动物，开发了一个具有生物学意义的竞争模拟模型。在此，我们展示该模型，比较有无种间交换贮藏食物时的竞争结果，并描述共存竞争者的种群动态。该模型预测，只有当通过搜寻因死亡而未设防的贮藏点或窃取设防贮藏点来进行贮藏种子的交换时，才会出现稳定共存。共存消费者之间的净相互作用范围从竞争（10%的情况）到宿主 - 寄生虫（77%）、共生（12%）和互利共生（1%）。共存消费者的种群动态通常表现出强烈的周期性以及耦合的同步或略有滞后的周期，这是之前未曾预料到的处于恒定环境中的沙漠啮齿动物会出现的情况。我们的模型证实，贮藏确实代表一种资源处理形式，可能在沙漠啮齿动物及其他贮藏动物群落的动态和多样性中发挥重要作用。
