Environmental Studies Department, 1156 High Street, University of California, Santa Cruz, California 95064, USA.
Ecology. 2012 Apr;93(4):921-9. doi: 10.1890/11-0165.1.
Due to the widespread eradication of large canids and felids, top predators in many terrestrial ecosystems are now medium-sized carnivores such as coyotes. Coyotes have been shown to increase songbird and rodent abundance and diversity by suppressing populations of small carnivores such as domestic cats and foxes. The restoration of gray wolves to many parts of North America, however, could alter this interaction chain. Here we use a 30-year time series of wolf, coyote, and fox relative abundance from the state of Minnesota, USA, to show that wolves suppress coyote populations, which in turn releases foxes from top-down control by coyotes. In contrast to mesopredator release theory, which has often considered the consequence of top predator removal in a three-species interaction chain (e.g., coyote-fox-prey), the presence of the top predator releases the smaller predator in a four-species interaction chain. Thus, heavy predation by abundant small predators might be more similar to the historical ecosystem before top-predator extirpation. The restructuring of predator communities due to the loss or restoration of top predators is likely to alter the size spectrum of heavily consumed prey with important implications for biodiversity and human health.
由于大型犬科和猫科动物已被广泛消灭，许多陆地生态系统中的顶级捕食者现在变成了中型肉食动物，如郊狼。郊狼通过抑制家猫和狐狸等小型肉食动物的数量，已被证明可以增加鸣禽和啮齿动物的数量和多样性。然而，灰狼在北美的许多地区的重新引入可能会改变这种相互作用链。在这里，我们使用了来自美国明尼苏达州的 30 年狼、郊狼和狐狸相对丰度的时间序列，表明狼抑制了郊狼的数量，这反过来又使狐狸免受郊狼的自上而下的控制。与中捕食者释放理论相反，该理论通常考虑了三物种相互作用链中顶级捕食者移除的后果（例如，郊狼-狐狸-猎物），而顶级捕食者的存在则在四物种相互作用链中释放了较小的捕食者。因此，大量小型捕食者的大量捕食可能更类似于顶级捕食者灭绝前的历史生态系统。由于顶级捕食者的丧失或恢复而导致的捕食者群落的重构，可能会改变大量被消耗猎物的大小范围，这对生物多样性和人类健康有重要影响。
