2019年高考英语天津卷阅读理解C详解(2)

Food webs may be dominated by many weak links because that arrangement is more stable over the long term.
食物网可能由许多薄弱环节主导，因为从长远来看，这种安排更稳定。
If a predator can eat several species，it can survive the extinction（灭绝）of one of them.
如果捕食者可以吃几个种类,如果他们其中一种灭绝，它还可以存活。
And if a predator can move on to another species that is easier to find when a prey species becomes rare，the switch allows the original prey to recover.
如果捕食者可以转移到另一个更容易找到的物种上，当一个猎物变得稀有时，这种转换使原来的猎物得以恢复。
The weak links may thus keep species from driving one another to extinction.
因此，这些薄弱的环节可能会阻止物种间的相互灭绝。
Mathematical models have also revealed that food webs may be unstable，where small changes of top predators can lead to big effects throughout entire ecosystems.
数学模型还显示，食物网可能是不稳定的，食物链顶端的捕食者的微小变化可能会导致整个生态系统的巨大影响。

In the 1960s，scientists proposed that predators at the top of a food web had a surprising amount of control over the size of populations of other species---including species they did not directly attack.