Mutations and variation within populations

Is there usually extensive genetic variation within a species' population?

Yes. Individuals usually have many genetic differences.

How do mutations contribute to variation within a population?

They create new alleles, which can introduce new genetic differences.

Do most mutations affect an organism's phenotype?

Most have no noticeable effect on the phenotype.

What effect can some mutations have on phenotype?

Some cause small changes in characteristics.

How often can a single mutation have a significant effect on phenotype?

Rarely, a single mutation can have a major effect.

Why do many mutations have no effect on phenotype?

They may occur in non-coding DNA or may not change the function of a protein.

Can mutations be beneficial, harmful or neutral?

Yes. Their effects depend on the mutation and the environment.

How can a beneficial mutation affect a population over generations?

If it increases reproductive success, natural selection may make the allele more common.