RESOURCE PRODUCTIVITY CONSUMER SPECIES-DIVERSITY - SIMPLE-MODELS OF COMPETITION IN SPATIALLY HETEROGENEOUS ENVIRONMENTS
RESOURCE PRODUCTIVITY CONSUMER SPECIES-DIVERSITY - SIMPLE-MODELS OF COMPETITION IN SPATIALLY HETEROGENEOUS ENVIRONMENTS
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DOI：
10.2307/1941639
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发表时间：
1988-10-01
期刊：
影响因子：
4.8
通讯作者：
ABRAMS, PA
中科院分区：
文献类型：
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作者：
ABRAMS, PA
利用简单的竞争模型研究了资源生产率与零星环境中可以共存的消费物种数量之间的关系。该分析试图确定多样性何时应随生产率增加，以及多样性与资源生产率之间何时应存在单峰关系。假设环境由多个独立的补丁组成，在这些补丁中发生了对一到两个资源的竞争。在单一资源模型中，生产力-多样性关系正在增加，除非发生资源枯竭以外的某些类型的种间竞争。在两种资源模型中，关于资源使用的差异化提供了一种额外的共存机制。通过四种不同的模型考察了生产力通过这一机制对共存条件的影响。这些模型的不同之处在于，资源在营养上是可替代的还是不可替代的，以及消费物种是否调整其两个消费速率常数的相对值以最大化适应度。每个模型的结果表明，根据资源增长的类型和生产率的定义，生产率-多样性关系既可能是递增的，也可能是单峰的。三个物种共存的条件表明，仅靠资源分化不太可能解释高度的物种多样性，特别是在不可替代资源的情况下。这一分析做出了与Tilman(1982)不同的预测，其中一个主要原因是Tilman(1982)假设生产率的提高意味着生产率的变异系数降低。因为有许多过程可以产生单峰和递增的生产率-多样性曲线，人们不能从这种关系中推断竞争的机制。
The relationship between resource productivity and the number of consumer species that can coexist in a patchy environment was examined using simple models of competition. The analysis seeks to determine when diversity should increase with productivity, and when there should be a unimodal relationship between diversity and resource productivity. The environment is assumed to consist of a number of independent patches in which competition occurs for one or two resources. In one-resource models, productivity-diversity relationships are increasing unless certain types of interspecific competition other than resource depletion occur. In two-resource models, differentiation with respect to use of the resources provides an additional mechanism for coexistence. The effects of productivity on coexistence conditions via this mechanism are examined using four different models. The models differ in whether resources are nutritionally substitutable or nonsubstitutable, and in whether the consumer species adjust the relative values of their two consumption rate constants to maximize fitness. Results for each model suggest that both increasing and unimodal productivity-diversity relationships are possible, depending on the type of resource growth and the definition of productivity. The conditions for coexistence of three species suggest that resource differentiation alone is unlikely to account for high species diversity, especially in the case of nonsubstitutable resources. This analysis makes different predictions than that of Tilman (1982) for several reasons; a major factor is that Tilman (1982) assumes that increasing productivity implies a decreasing coefficient of variation in productivities. Because there are many processes that can produce unimodal and increasing productivity-diversity curves, one cannot infer the mechanism of competition from this relationship.