Collaborative Research: Does Anti-predator Behavior Modify Indirect Effects of Top Predators?

食肉动物可以通过吓跑食草动物或食草动物来保护植物，并防止过度放牧，这一过程被称为？营养级联?生物学家假设每一种捕食者都会产生一种营养级联。例如，老虎会吓跑食草动物，并保护其巡逻区域内生长的植物。然而，有证据表明，并不是所有的食草动物对捕食者的恐惧都有一致的反应。相反，在有多种食草动物的生态系统中，每一种食草动物都可能避开最不可能逃脱捕食者的区域，这些区域可能会有所不同。如果是这样，那么食肉动物就会引发一系列的营养级联反应，使任何特定食草动物最可能被捕获的地方的植物受益。为了了解捕食者如何通过吓跑食草动物来保护植物，生物学家必须确定每个猎物最不可能逃脱的区域或栖息地类型。这种识别需要了解猎物的逃跑策略。拟议中的研究将使用华盛顿两种食草动物的逃生策略。骡子和白尾鹿？为了预测最近灰狼的回归给它们的栖息地带来的变化。骡鹿行动缓慢，用躲避的步态来躲避捕食者。他们应该转移到崎岖的地形，在那里他们的敏捷性是有利的，避免平坦的地形，因为逃跑需要速度，以应对狼的恐惧。白尾鹿跑得很快，能迅速逃离捕食者；它们应该避开崎岖的地形，在那里它们的速度在受到狼的惊吓时会被抵消。因此，狼应该保护生长在平缓地形上以骡鹿为食的植物，以及生长在崎岖地形上以白尾鹿为食的植物。该项目将通过强调猎物逃跑行为在驱动捕食者如何影响植物和塑造生态系统中的重要性，改变人们对捕食者生态作用的理解方式。这项研究的广泛影响包括培养了两名博士生，建立了一项关于狼对生态影响的长期研究，作为为保护政策提供信息的手段，并启动了一项包括教师培训、公开讲座和中学课堂视频课程计划的推广计划。

Predators can benefit plants by scaring away herbivores, or plant-eaters, and preventing overgrazing in a process known as a ?trophic cascade?. Biologists have assumed that each predator creates one kind of trophic cascade. A tiger, for example, scares herbivores away from and protects plants growing in the area it patrols. Evidence suggests, however, that not all herbivores respond uniformly to the fear of predators. Instead, in ecosystems with multiple herbivores, each one may avoid the area where it is least likely to escape the predator, and these areas might differ. If so, then predators could trigger an array of trophic cascades, benefitting plants eaten by any particular herbivore where it is most likely to be caught. To understand how a predator shields plants by scaring away herbivores, biologists must identify the area, or habitat type, where each prey species is least likely to escape. Such identification requires knowledge of prey escape tactics. The proposed research will use escape tactics of two herbivores in Washington ? mule and white-tailed deer ? to predict changes to their habitat use caused by the recent return of the gray wolf. Mule deer are slow and use an evasive gait to escape predators. They should shift to rough terrain where their agility is advantageous, and avoid smooth terrain where escape requires speed, in response to fear of wolves. White-tailed deer are fast and escape predators by sprinting away; they should avoid rugged terrain where their speed is neutralized when frightened by wolves. Consequently, wolves should protect plants eaten by mule deer that grow on gentle terrain, and plants eaten by white-tailed deer that grow on rugged terrain. The project will change the way that the ecological role of predators is understood by highlighting the importance of prey escape behavior in driving how predators affect plants and shape ecosystems.The broader impacts of the research include training of two doctoral students, establishment of a long-term study of the ecological impacts of wolves as a means to inform conservation policy, and initiation of an outreach program incorporating teacher training, public lectures, and video lesson plans for secondary school classrooms.