Division of Ecology and Evolutionary Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow, UK.
Oecologia. 2010 Oct;164(2):411-21. doi: 10.1007/s00442-010-1681-6. Epub 2010 Jun 19.
Flowers attract insects and so are commonly exploited as foraging sites by sit-and-wait predators. Such predators can be costly to their host plant by consuming pollinators. However, sit-and-wait predators are often prey generalists that also consume plant antagonists such as herbivores, nectar robbers and granivores, so may also provide benefits to their host plant. Here we present a simple, but general, model that provides novel predictions about how costs and benefits interact in different ecological circumstances. The model predicts that the ecological conditions in which flower-dwelling predators are found can generate either net benefits to their host plants, net costs to their host plants, or can have no effect on the fitness of their host plants. The net effect is influenced by the relative densities of mutualists and antagonists. The flower-dwelling predator has a strong positive effect on the plant if both the pollinators and the granivores are at high density. Further, the range of density combinations that yield a positive net outcome for the plant increases if the performance of pollinators is negatively density dependent, if the predator is only moderately effective at influencing flower visitor rates by its potential prey, and if pollinators are very effective. If plants of a given species find themselves consistently in conditions where they benefit from the presence of a predator then we predict that natural selection could favour the evolution of plant traits that increase the likelihood of predator recruitment and retention, especially where plants are served by highly effective pollinators.
花朵吸引昆虫，因此通常被坐待型捕食者用作觅食场所。这些捕食者通过消耗传粉者，对其宿主植物来说可能是昂贵的。然而，坐待型捕食者通常是猎物泛化者，也会消耗植物的天敌，如食草动物、花蜜盗贼和食谷者，因此也可能为其宿主植物带来好处。在这里，我们提出了一个简单但通用的模型，该模型对不同生态环境下的成本和收益如何相互作用提供了新的预测。该模型预测，在花栖捕食者存在的生态条件下，它们可能对其宿主植物产生净收益、净成本，或者对其宿主植物的适应性没有影响。净效应受共生者和天敌的相对密度的影响。如果传粉者和食谷者的密度都很高，花栖捕食者对植物有很强的积极影响。此外，如果传粉者的表现呈密度依赖性负相关，如果捕食者通过其潜在猎物对花访客率的影响只是适度的，如果传粉者非常有效，那么对植物产生正向净结果的密度组合范围将会增加。如果一个给定物种的植物发现自己始终处于从捕食者存在中受益的条件下，那么我们预测自然选择可能有利于植物特征的进化，从而增加捕食者招募和保留的可能性，特别是在植物受益于高效传粉者的情况下。
