Borrvall Charlotte, Ebenman Bo
Ecol Lett. 2006 Apr;9(4):435-42. doi: 10.1111/j.1461-0248.2006.00893.x.
The large vulnerability of top predators to human-induced disturbances on ecosystems is a matter of growing concern. Because top predators often exert strong influence on their prey populations their extinction can have far-reaching consequences for the structure and functioning of ecosystems. It has, for example, been observed that the local loss of a predator can trigger a cascade of secondary extinctions. However, the time lags involved in such secondary extinctions remain unexplored. Here we show that the loss of a top predator leads to a significantly earlier onset of secondary extinctions in model communities than does the loss of a species from other trophic levels. Moreover, in most cases time to secondary extinction increases with increasing species richness. If local secondary extinctions occur early they are less likely to be balanced by immigration of species from local communities nearby. The implications of these results for community persistence and conservation priorities are discussed.
顶级食肉动物对人类引起的生态系统干扰极为脆弱，这一问题日益受到关注。由于顶级食肉动物通常对其猎物种群施加强大影响，它们的灭绝会对生态系统的结构和功能产生深远后果。例如，据观察，某一捕食者在当地消失会引发一系列次生灭绝。然而，此类次生灭绝所涉及的时间滞后问题仍未得到探究。在此我们表明，在模型群落中，顶级食肉动物的消失比其他营养级物种的消失会导致次生灭绝显著更早发生。此外，在大多数情况下，次生灭绝的时间会随着物种丰富度的增加而延长。如果当地次生灭绝发生得早，那么它们就不太可能被附近当地群落物种的迁入所平衡。本文讨论了这些结果对群落持久性和保护优先级的影响。
