A graphical model of keystone predators in food webs: Trophic regulation of abundance, incidence, and diversity patterns in communities
A graphical model of keystone predators in food webs: Trophic regulation of abundance, incidence, and diversity patterns in communities
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DOI：
10.1086/285879
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发表时间：
1996-05-01
影响因子：
2.9
通讯作者：
Leibold, MA
中科院分区：
文献类型：
--
作者：
Leibold, MA
我分析了一个物种相互作用的模型，该模型涉及竞争单一资源并共享共同的“基石捕食者”的物种，以研究生产力(资源的潜在承载能力)的“自下而上”的影响，以及影响捕食者死亡率的因素对结果集合中的多样性、丰富度和分布模式的“自上而下”的影响。该模型预测，这些物种将在中等生产力(顶级捕食者的中等死亡率)下共存，优势资源开采者将在低生产率(和高捕食者死亡率)时占据主导地位，而抵抗捕食者的形式将在高生产力(和低捕食者死亡率)时占据主导地位。在这个模型中，捕食者和资源的密度对生产力的变化是“缓冲的”，但处于中间营养水平的物种的密度却不是。该模型预测，随着生产力的提高或捕食者死亡率的降低，由于潜在的这类物种的数量很大，从良好的资源开采者到抵抗捕食者的物种，将会出现多对物种的更替系列。在这种情况下，共存最有可能是更相似的形式，但相似物种的丰度预计将呈负相关。此外，所有营养水平的生物体总密度与生产力的变化有关。时空异质性通过允许两个以上物种在单一资源和单一捕食者存在的情况下共存，并允许共存竞争者的丰度存在正向协变，从而修正了这些预测。这些模型显示了物种组成周转在决定食物链对生产力和捕食者死亡率变化的自下而上和自上而下调节的反应中的关键作用。这些模型还预测了单峰多样性与生产力曲线的关系，这在一定程度上取决于顶级捕食者对猎物的专一性程度。
I analyze a model of species interactions involving species that compete for a single resource and share a common ''keystone predator'' to study the ''bottom-up'' effects of productivity (potential carrying capacity of the resource) and the ''top-down'' effects of factors that affect the death rate of the predator on diversity, abundance, and distribution patterns in the resulting assemblages. The model predicts that coexistence of such species will occur at intermediate productivity (and at intermediate death rates on the top predator) and that superior resource exploiters will dominate at low productivity (and high predator death rates), whereas predator-resistant forms will dominate at high productivity (and low predator death rates). In this model, predator and resource densities are ''buffered'' against variation in productivity, but the densities of species at the intermediate trophic level are not. Given a large ''pool'' of potential such species, the model predicts a replacement series involving multiple pairs of species ranging from good resource exploiters to predator-resistant forms as productivity increases or predator death rates decrease. In such a case, coexistence is most likely among the more similar forms, but abundances of similar species are predicted to be negatively correlated. Furthermore, the overall density of organisms at all trophic levels is correlated with variation in productivity. Spatiotemporal heterogeneity modifies these predictions by allowing more than two species to coexist in the presence of a single resource and a single predator and by permitting positive covariation in the abundances of coexisting competitors as well. These models show the critical role of species compositional turnover in determining food web responses to bottom-up and top-down regulation by productivity and variation in predator death rates. The models also predict unimodal diversity versus productivity curves that depend in part on the degree of prey specificity by the top predator.