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Helpful mutations
Name: Amanda E Kulik
Location: N/A
Country: N/A
Date: N/A
Question:
When can mutations be considered helpful?
Replies:
Mutations are considered helpful if they lead to a trait in the organism that
helps it survive better in its environment. Remember, you can't make this judgement at
the time the mutation occurred, because the environment may change and the silent,
non-harmful mutation might then become helpful. If it is, then individuals carrying
the mutation will survive better than those that don't. This is the basis of Darwin's
theory of natural selection. First you have genetic diversity in a species, that is to
say, different mutations in the genome. Then the environment acts on that diversity to
select certain individuals for better survival. In different environments, mutations
may have very different effects. For example, the disease sickle-cell anemia is harmful
in most parts of the world. It is particularly prevalent among Africans and
African-Americans. Why doesn't it just die out? Because in Africa, people with
the mutation on just one of the two chromosomes (carriers, or in genetic terminology
heterozygotes) are more resistant to malaria, so the mutation is selected for by the
environment.
-ProfBill
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Update: June 2012
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