Klopfer E D, Ives A R
Department of Zoology, University of Wisconsin-Madison 53706, USA.
Theor Popul Biol. 1997 Dec;52(3):167-78. doi: 10.1006/tpbi.1997.1335.
In nature, many insect species are attacked by more than one specialized species of parasitoid. We examine whether parasitoid aggregation among patches containing hosts can promote the coexistence of specialized parasitoids on the same host species. We construct models to analyze the effects of three types of parasitoid aggregation: direct density-dependent, inverse density-dependent, and density-independent aggregation. All three types of aggregation may facilitate coexistence, provided the parasitoid species show behavioral differences that produce different patterns of aggregation. By deriving general conditions of coexistence of parasitoids, we show that all three types of aggregation act to facilitate coexistence in the same way--by increasing the covariance between the distributions of susceptible hosts and the least common parasitoid. Although they act in the same way, in general the effect of density-independent aggregation in facilitating coexistence is greater than either direct or inverse density-dependent aggregation. This suggests that density-independent aggregation may have the greatest potential to facilitate the coexistence of specialize parasitoids using the same host.
在自然界中，许多昆虫物种会受到不止一种特化的寄生蜂物种的攻击。我们研究了含有宿主的斑块之间寄生蜂的聚集是否能促进特化寄生蜂在同一宿主物种上的共存。我们构建模型来分析三种类型的寄生蜂聚集的影响：直接密度依赖型、逆密度依赖型和密度独立型聚集。只要寄生蜂物种表现出产生不同聚集模式的行为差异，所有这三种类型的聚集都可能促进共存。通过推导寄生蜂共存的一般条件，我们表明所有这三种类型的聚集都以相同的方式促进共存——通过增加易感宿主分布与最不常见寄生蜂分布之间的协方差。虽然它们的作用方式相同，但一般来说，密度独立型聚集在促进共存方面的效果大于直接或逆密度依赖型聚集。这表明密度独立型聚集可能最有潜力促进使用同一宿主的特化寄生蜂的共存。
