[求助]GWD 14 第二篇阅读里有句话不懂,请各位帮帮忙.

Deboisseu

Low levels of straying

are crucial, since the process

provides a source of novel

genes and a mechanism

      by which a location can be

 (40)     repopulated should the fish

there disappear.

这句话是什么意思阿? mechanism by which a lovation can be repopulated should the fish. 这是个倒装吧？不倒装的是什么样的呢？有了个动词can 又来个should，哪个才是个从句的动词阿？

Deboisseu

谢谢，那后面的that从句变成should the fish, 是什么语法现象？倒装的话，请问这里为什么可以倒装？