Neutral Theory and Genetic Drift

Flashcards reviewing key concepts and generalizations related to neutral theory, genetic drift, and their effects on allele frequencies and heterozygosity.

What does genetic drift do to variation?

It reduces variation.

What process can counteract genetic drift?

Mutation

What does the Neutral Theory explain?

Explains the generation and evolution of variation as a combination of mutation and genetic drift.

What does the Neutral Theory say?

Much molecular variation is selectively neutral, or close to it; Such variation evolves by drift alone; Neutral substitutions in a lineage will occur at a constant rate.

The chances that any INDIVIDUAL neutral mutation will become fixed are…

Lower in a large population than in a small population.

Rate of Fixation of New Neutral Alleles Depends on…

Rate of neutral mutation.

Does the rate of fixation of new neutral alleles depend on population size?

Does not depend on population size.

Does the time to fixation depend on population size?

Depends on population size.

What is the result of neutral alleles being substituted at a constant rate?

Differences arise steadily, on average.

What happens to heterozygosity with drift?

Decreases with drift, and is lower in small populations than large ones.

What is the key idea of Coalescence Theory?

Eventually one allele will become fixed and all others will go extinct; Therefore, eventually only one copy of that one allele will remain, and all other copies will go extinct.