Mutation: The Source of New Variation
New Alleles Begin with Mutation
What mutation is
A mutation is a change in DNA. Mutations can happen when DNA is copied incorrectly or when DNA is damaged by environmental factors.
Mutations are random with respect to need
Mutations do not appear because an organism needs them. They occur without regard to what would be helpful, although natural selection can later favor useful mutations.
Types of mutation effects
Helpful
- Increases survival or reproduction in a given environment
- May spread through a population
Neutral
- Has little or no effect on survival or reproduction
- May persist by chance
Common misconception
Mutation is not the same as evolution. Mutation creates variation; evolution is the change in the frequency of that variation over time.
Why are mutations important in evolution?
Without mutation, populations would have far less new genetic variation.
Correct answer: They create new genetic variation
Why can mutations be harmful, neutral, or helpful?
A change can affect function in different ways depending on context.
Correct answer: Because their effects depend on where they occur in DNA and on the environment.
From mutation to evolutionary change
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1
A DNA change occurs.
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2
The mutation creates or alters an allele.
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3
The allele affects a trait, or has no effect.
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4
Natural selection or chance changes how common it becomes.
Mutations arise with respect to which statement?
Mutations occur randomly with respect to what would be useful.
Correct answer: Random DNA changes