The founder effect is a decrease in genetic diversity caused by a small colony of individuals remaining isolated, leading to genetic drift and the concentration of certain genetic traits. It can eventually lead to the formation of a new species. The Amish are an example of this effect. It is of concern to biologists trying to save endangered species.
The founder effect is a drastic decrease in genetic diversity caused by the formation of a small colony of individuals that remain isolated. This contributes to genetic drift, which causes some genetic traits to fade away or become more abundant. Several human populations provide interesting study sources for geneticists interested in the founder effect, as do numerous animal populations.
This concept was first widely discussed in 1952, when Ernst Mayr built on earlier theoretical work by others to elaborate on the idea of the founder effect. Mayr showed how small isolated populations can begin to diverge from their larger parental populations, sometimes eventually producing a unique species. Since then, others have greatly expanded his work by performing long-term studies of isolated communities and using advanced tools to analyze the genomes of organisms in these populations.
In a classic example of the founder effect, a small group separates itself from a larger population, just as the Amish did during the Reformation. When a small group remains endogamous, meaning that people intermarry within the community, it can create a situation where genetic diversity is extremely limited, because no new members are welcomed into the community. This effect is common among isolated religious communities and island populations, both of which tend to be cut off from the larger population.
One effect of this phenomenon is the tendency of some genetic traits to become concentrated. Because the founding community is so small, if one person carries a genetic mutation, that mutation can be amplified in the community. For example, the Amish have a much higher incidence of hexadactyly than the general population. Problems attributed to inbreeding are an example of the founder effect.
If a founder population is left alone long enough, it can diverge so radically from the parent population that it becomes an entirely new species. Charles Darwin noticed this when he explored the animals of the Galapagos Islands, although he didn’t understand the cause. Most people agree that the founder effect can be extremely problematic, because decreasing genetic diversity can lead to an increase in the manifestation of genetic mutations. This is of particular interest to biologists who are trying to save endangered species, as they must raise small starter populations responsibly to minimize this effect. This is one reason why conservation parks are constantly trading animals.
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