Virginia Polytechnic Institute and State University, Department of Fish and Wildlife Conservation, Blacksburg, Virginia, USA.
Michigan State University, Department of Fisheries and Wildlife, East Lansing, Michigan, USA.
Ecology. 2024 Nov;105(11):e4429. doi: 10.1002/ecy.4429. Epub 2024 Sep 30.
Defensive traits are hypothesized to benefit prey by reducing predation risk from a focal predator but come at a cost to the fitness of the prey. Variation in the expression of defensive traits is seen among individuals within the same population, and in the same individual in response to changes in the environment (i.e., phenotypically plastic responses). It is the relative magnitude of the cost and benefit of the defensive trait that underlies the defensive trait expression and its consequences to the community. However, whereas the cost has received much attention in ecological research, the benefit is seldom examined. Even in a defensive trait as extensively studied as vigilance, there are few studies of the purported benefit of the behavior, namely that vigilance enhances survival. We examined whether prey vigilance increased survival and quantified that benefit in a natural system, with white-tailed deer (Odocoileus virginianus) experiencing unmanipulated levels of predation risk from Florida panther (Puma concolor coryi). Deer that spent more time vigilant (as measured by head position using camera trap data) had a higher probability of survival. Indeed, an individual deer that was vigilant 75% of the time was more than three times as likely to be killed by panthers over the course of a year than a deer that was vigilant 95% of the time. Our results therefore show that within-population variation in the expression of a defensive trait has profound consequences for the benefit it confers. Our results provide empirical evidence supporting a long-held but seldom-tested hypothesis, that vigilance is a behavior that reduces the probability of predation and quantifies the benefit of this defensive trait. Our work furthers an understanding of the net effects of a trait on prey fitness and predator-prey interactions, within-population variation in traits, and predation risk effects.
防御性状被假设通过降低来自焦点捕食者的捕食风险使猎物受益，但这会对猎物的适应度造成代价。同一种群内的个体之间以及同一个体对环境变化（即表型可塑性反应）都会表现出防御性状的表达变化。防御性状的表达及其对群落的后果，取决于防御性状的成本和收益的相对大小。然而，尽管成本在生态研究中受到了广泛关注，但收益却很少被研究。即使在像警戒这样被广泛研究的防御性状中，也很少有研究关注该行为的所谓收益，即警戒提高了生存能力。我们检验了猎物的警戒是否会提高生存能力，并在一个自然系统中量化了这种收益，白尾鹿（Odocoileus virginianus）经历了佛罗里达美洲狮（Puma concolor coryi）未受操纵的捕食风险。头部位置通过相机陷阱数据进行测量，警戒时间更长的鹿的生存概率更高。事实上，在一年的时间里，一只保持 75%警戒时间的鹿被美洲狮杀死的可能性是保持 95%警戒时间的鹿的三倍多。因此，我们的结果表明，防御性状表达的种群内变异对其赋予的收益具有深远的影响。我们的结果为一个长期存在但很少被测试的假设提供了经验证据，即警戒是一种降低被捕食概率的行为，并量化了这种防御性状的收益。我们的工作进一步了解了性状对猎物适应度和捕食者-猎物相互作用、性状的种群内变异和捕食风险效应的净影响。
