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12 Cards in this Set
- Front
- Back
How often base substitution occurs depends on whether the mutation is:
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Neutral (no change in fitness)
Deleterious (Decreasing in fitness) Beneficial/Advantageous (increasing fitness-positively selected) |
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In any population with ____ size (N), a new neutral mutation can reach fixation by _______
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finite / genetic drift
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2N alleles at the locus, including _______, are ______ likely to be fixed in the future
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this new mutation / equally
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The fixation probability of a neutral mutation is _____
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1/(2N)
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If all mutations are neutral, the substitution rate per generation (k/t) is simply _______
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the mutation rate
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Neutral Mutations:
Relative fitness: Fixation prob.: Substitution rate per gener.: |
1
1/(2N) mu |
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Deleterious mutation:
Relative fitness: Fixation prob.: Substitution rate per gener.: |
1-s
0 0 |
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Beneficial Mutation
Relative fitness: Fixation prob.: Substitution rate per gener.: |
1+s
pfix >>1/(2N) probability of fixation is high if the mutation is + selected 2N(mu)pfix>>(mu) DNA seq evolves much faster than under genetic drift |
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If all mutations are neutral:
The expected divergence : |
D=L x mu x 2t
L =sequence length (bp) mu=mutation rate per bp 2t=divergence time |
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Evolution of protein-coding seq:
First Kind |
1. Mutations that do not change amino acid sequence (mutations at synonymous sites)
No change in function of protein or in fitness NEUTRAL mutations |
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Evolution of protein-coding seq:
Second kind: |
2.Mutations that change amino acid sequence (nonsynonymous sites)
Either: Functional change-->No Fitness change --> Neutral (f0) Or: Functional change--> Change in fitness--> deleterious (f1) or advantageous (f2) or no/little functional change--> neutral (f0) |
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f0 + f1 + f2 =
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1
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