What does the founder effect mean?

Founder effect (English: founder effect, also known as founder effect or founder effect and ancestor effect) is a form of genetic drift, which means that a few individuals with certain alleles in the parent population re-establish a new population. Although the number of this population will increase in the future, there is little genetic difference between them because they have not mated with other biological groups. This situation generally occurs in isolated islands or relatively closed newly opened villages.

There is a good example to explain this phenomenon: in a remote mountain village in Venezuela, the probability of people suffering from Huntington's disease is much higher than the outside world. Because at the beginning of19th century, a woman with Huntington's disease gene spread her gene among individual villagers. [1][2] Subsequent historical development did not involve new genes, resulting in the whole village enjoying this morbid gene. Source: Wikipedia