Department of Biology, McGill University, 1205 Avenue Docteur Penfield, Montreal, Quebec H3A 1B1, Canada.
Am Nat. 2010 Feb;175(2):E16-34. doi: 10.1086/649579.
Synchrony has fundamental but conflicting implications for the persistence and stability of food webs at local and regional scales. In a constant environment, compensatory dynamics between species can maintain food web stability, but factors that synchronize population fluctuations within and between communities are expected to be destabilizing. We studied the dynamics of a food web in a metacommunity to determine how environmental variability and dispersal affect stability by altering compensatory dynamics and average species abundance. When dispersal rate is high, weak correlated environmental fluctuations promote food web stability by reducing the amplitude of compensatory dynamics. However, when dispersal rate is low, weak environmental fluctuations reduce food web stability by inducing intraspecific synchrony across communities. Irrespective of dispersal rate, strong environmental fluctuations disrupt compensatory dynamics and decrease stability by inducing intermittent correlated fluctuations between consumers in local food webs, which reduce both total consumer abundance and predator abundance. Strong correlated environmental fluctuations lead to (i) spatially asynchronous and highly correlated local consumer dynamics when dispersal is low and (ii) spatially synchronous but intermediate local consumer correlation when dispersal is high. By controlling intraspecific synchrony, dispersal mediates the capacity of strong environmental fluctuations to disrupt compensatory dynamics at both local and metacommunity scales.
同步对本地和区域尺度的食物网的持久性和稳定性具有基本但相互矛盾的影响。在恒定的环境中，物种之间的补偿动态可以维持食物网的稳定性，但预期会使种群波动在社区内和社区之间同步的因素会破坏稳定性。我们研究了一个元社区中食物网的动态，以确定环境变异性和扩散如何通过改变补偿动态和平均物种丰度来影响稳定性。当扩散率较高时，较弱的相关环境波动通过减少补偿动态的幅度来促进食物网的稳定性。然而，当扩散率较低时，较弱的环境波动通过在社区之间诱导种内同步来降低食物网的稳定性。无论扩散率如何，强烈的环境波动都会通过在本地食物网中诱导消费者之间间歇性相关波动来破坏补偿动态并降低稳定性，从而降低总消费者丰度和捕食者丰度。强烈的相关环境波动导致（i）当扩散率较低时，空间上异步且高度相关的本地消费者动态，以及（ii）当扩散率较高时，空间上同步但中间的本地消费者相关性。通过控制种内同步，扩散在本地和元社区尺度上调节了强烈的环境波动破坏补偿动态的能力。
