Hunters versus Hunted: New perspectives on the physiological costs of survival at the top of the food chain

Global biotic and abiotic threats,particularly from pervasive human activities, are progressively pushing large, apex carnivorous mammals into the functional role of mesopredator. Hunters are now becoming the hunted. Despite marked impacts on these animals and the ecosystems in which they live, little is known about the physiological repercussions of this role downgrading from ultimate to penultimate predator. Here we examine how such ecological role reversals alter the physiological processes associated with energy expenditure, and ultimately the cost of survival during peak performance. Taxonomic group, preferred habitat, and domestication affected the capacity of the oxygen pathway to support high levels of aerobic performance by carnivorous mammals. Fear responses associated with anthropogenic threats also impacted aerobic capacity.  Allometric trends for three energetic metrics (maximum oxygen consumption, field metabolic rates, and the cost per stride or step), showed di...全球生物与非生物威胁，尤其是源自人类活动的广泛影响，正逐步将大型顶级食肉哺乳动物（apex carnivorous mammals）推至中型捕食者（mesopredator）的生态功能位，昔日猎手已然沦为猎物。尽管这一转变对这些动物及其栖息的生态系统造成了显著影响，但学界对其从顶级捕食者降级为次顶级捕食者所带来的生理效应仍知之甚少。 本研究旨在探究此类生态角色反转如何改变与能量消耗相关的生理过程，最终明确其在巅峰生理状态下的生存代价。 食肉哺乳动物的分类类群、偏好栖息生境与驯化状态，均会影响其氧气通路支撑高水平有氧代谢能力的效能；与人为威胁相关的恐惧反应同样会对有氧代谢能力产生影响。 三项能量指标（最大耗氧量、野外代谢率以及每步或每跨步的能量成本）的异速生长趋势呈现出……