The founder effect refers to the fact that a small number of individuals in a biological population reproduce and grow under conditions of isolation from the original population due to geographical isolation or other reasons. Although the population of the offspring has continued to expand, the genetic information of the entire population comes from the few individuals who originally migrated. The founder effect results in lower genetic diversity of the ethnic group, poor adaptability to the environment, and easy to be naturally eliminated. According to the above definition, Which of the following situations are caused by the founder effect:. ['coffee trees on the island of Sri Lanka have all died of lack of resistance to coffee rust.', 'the shells of an island are often picked by fishermen because of their bright colors and are now endangered.', 'pandas are threatened with extinction due to reduced populations.', 'In order to preserve their own culture, Amish people do not marry outsiders, resulting in frequent genetic diseases.']