DeWitt Philip D, Schuler Matthew S, Visscher Darcy R, Thiel Richard P
Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9
Science and Research Branch, Ontario Ministry of Natural Resources and Forestry, Peterborough, Ontario, Canada K9J 3C7.
Proc Biol Sci. 2017 Jul 12;284(1858). doi: 10.1098/rspb.2017.0757.
Animal populations are regulated by the combined effects of top-down, bottom-up and abiotic processes. Ecologists have struggled to isolate these mechanisms because their effects on prey behaviour, nutrition, security and fitness are often interrelated. We monitored how forage, non-consumptive effects (NCEs), consumptive predation and climatic conditions influenced the demography and nutritional state of a wild prey population during predator recolonization. Combined measures of nutrition, survival and population growth reveal that predators imposed strong effects on the prey population through interacting non-consumptive and consumptive effects, and forage mechanisms. Predation was directly responsible for adult survival, while declining recruitment was attributed to predation risk-sensitive foraging, manifested in poor female nutrition and juvenile recruitment. Substituting nutritional state into the recruitment model through a shared term reveals that predation risk-sensitive foraging was nearly twice as influential as summer forage conditions. Our findings provide a novel, mechanistic insight into the complex means by which predators and forage conditions affect prey populations, and point to a need for more ecological studies that integrate behaviour, nutrition and demography. This line of inquiry can provide further insight into how NCEs interactively contribute to the dynamics of terrestrial prey populations; particularly, how predation risk-sensitive foraging has the potential to stabilize predator-prey coexistence.
动物种群受到自上而下、自下而上和非生物过程的综合影响。生态学家一直难以分离出这些机制，因为它们对猎物行为、营养、安全和适应性的影响往往相互关联。我们监测了在捕食者重新定殖期间，食物、非消费性影响（NCEs）、消费性捕食和气候条件如何影响野生猎物种群的种群统计学和营养状况。营养、生存和种群增长的综合指标表明，捕食者通过非消费性和消费性影响的相互作用以及食物机制，对猎物种群产生了强烈影响。捕食直接影响成年个体的存活，而幼体补充数量的下降则归因于对捕食风险敏感的觅食行为，表现为雌性营养状况不佳和幼体补充数量减少。通过一个共同的术语将营养状况代入补充模型，结果表明，对捕食风险敏感的觅食行为的影响力几乎是夏季食物条件的两倍。我们的研究结果为捕食者和食物条件影响猎物种群的复杂方式提供了一种新颖的、基于机制的见解，并指出需要更多整合行为、营养和种群统计学的生态学研究。这一系列的研究可以进一步深入了解非消费性影响如何相互作用，从而影响陆地猎物种群的动态；特别是，对捕食风险敏感的觅食行为如何有可能稳定捕食者 - 猎物的共存关系。
