(Mendelian) Genetic Evolution in Population: Mutation (lect 07)

Mutation

Permanent change in DNA sequence

Germline mutation

Mutation occurring in reproductive cells that can be inherited

Somatic mutation

Mutation occurring in body cells that is not inherited

Mutation rate

Probability that a gene mutates per generation

Neutral mutation

Mutation with no effect on fitness

Deleterious mutation

Mutation that reduces fitness

Beneficial mutation

Mutation that increases fitness

Standing genetic variation

Existing genetic diversity within a population

Novel variation

New genetic variation created by mutation

Mutation pressure

Force of mutation introducing new alleles into a population

Mutations occur constantly

Do mutations occur rarely or constantly, in all organisms and all populations?

No mutation rates vary (on gene and organism)

Do all genes mutate at the same rate?

Why does mutation still occur frequently in humans despite low per-base mutation rates?

Because the human genome contains about 3.5 billion base pairs, providing many opportunities for mutations during reproduction.

Only germline mutations are inherited

Which mutations are passed to offspring?

Large population sizes & large genomes (allows for more mutations)

Why is the total number of mutations in a population high even though mutation rates per gene are low?

No

Do mutation rates significantly change allele frequencies over short evolutionary timescales?

Frequency of new mutations is small (compared to existing allele frequencies)

Why are mutation effects difficult to detect in short-term population genetic studies?

Over thousands to hundred thousand years

Over what timescale does mutation significantly influence genetic variation?

Mutation is the ultimate source of all new genetic variation

If mutation has little short-term effect, why is it still essential for evolution?

No (only mutation, other forces change frequencies)

Can natural selection or genetic drift create new alleles?

Genetic variation would stop

What would happen to evolution if mutations stopped occurring?