Founder effect refers to that a few individuals in a biological population reproduce and live in isolation from the original population due to geographical isolation or other reasons. Although the offspring population continues to expand, the genetic information of the whole population comes from the first migrating few individuals. Founder effect causes low genetic diversity, poor adaptability to the environment and easy to be eliminated by nature.
According to the above definition, which of the following situations is caused by the founder effect:
Coffee trees on the island of Sri Lanka died due to lack of resistance to coffee rust