Founder effect and the bottleneck effect of founder effect

These two effects will also affect the gene frequency of the population. Sometimes several or dozens of individuals will separate from a large population and move to another area, isolated from the original population. In this case, the gene frequency of the new population established by these separated individuals is not necessarily the same as that of the original large population. If the genotype of most individuals in this population is AA, the frequency of this gene appearing in the new population will greatly increase. That is to say, the gene frequency of the new population depends on the genotypes of the first few or dozens of individuals, regardless of whether they are favorable in selection. This is the founder effect (also called founder effect), which is another form of gene drift. For example, the Dunkir people in Pennsylvania, USA, migrated from West Germany in the early18th century and were used to intermarriage. The survey found that the gene frequencies of some traits in these people are different from those in West Germany. About 45% people in western Germany have type A blood, and both type B blood and type AB blood account for 15%. However, 60% of Dunkir people have type A blood, while only 5% people have type B and AB blood.