问GWD里的一句话，不太理解

yuanzi15

 Low levels of straying are crucial, since the process provides a source of novel genes and a mechanism by which a location can be repopulated should the fish there disappear.  尤其是红字部分，什么语法啊，不太理解，请高手指点

ad264

我试着解释，
Should you have any question, please feel free to let me know.
如果你有任何问题的话，不要客气告诉我

这个过程(鱼会走丢)，提供一个新基因的来源以及一个机制。什麽机制呢？就是当鱼如果消失了(指鱼游到大海去了)，一地还可以重新有鱼回住(鱼回家了)。

语法上，should 是假设语气跟if一样

yuanzi15

解释得非常到位，感谢ing!