That's when we started having problems of inbreeding depression that can kill the local population in a very short term.
从那时起开始出现近亲繁殖衰退的问题,这可能会在很短的时间内使当地的种群灭绝。
英语百科
Inbreeding depression
Inbreeding depression is the reduced biological fitness in a given population as a result of inbreeding, or breeding of related individuals. Population biological fitness refers to its ability to survive and reproduce itself. Inbreeding depression is often the result of a population bottleneck. In general, the higher the genetic variation or gene pool within a breeding population, the less likely it is to suffer from inbreeding depression.