EvolutionLesson 1 of 1 in the course Genetic drift and gene flow

Genetic Drift: Sampling, Bottlenecks, Fixation, and Population Size

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Genetic drift is an evolutionary process driven by chance. This lesson introduces how random events change allele frequencies and why those changes can reduce variation in a population.

An allele is one version of a gene. The frequency of an allele is the proportion of gene copies in a population that are that version. Genetic drift is a change in the frequency of an existing allele caused by chance rather than because the allele gives its carriers a survival or reproductive advantage.

All flashcards

Genetic drift
Random change in allele frequency from one generation to another.
Effective population size (NeN_e)
The size of an idealized population experiencing the observed strength of drift.
Founder effect
Chance changes in allele frequencies when a small group establishes a new population.
Genetic draft
Allele-frequency change caused by selection acting on linked loci.
Wright–Fisher model
A model of independent allele sampling across non-overlapping generations.

Quiz questions

  1. Which population structure is assumed by the Wright–Fisher model?Answer: Non-overlapping generations with independent sampling of gene copies.
  2. With drift acting alone, what is the eventual fixation probability of a neutral allele currently at frequency 0.3?Answer: 0.3
  3. What defines the founder effect?Answer: A small group separates from a larger population and establishes a new one.
  4. What does effective population size represent?Answer: The size of an idealized population with the observed strength of drift.
  5. What causes genetic draft at a locus?Answer: Selection acting on linked loci.

Based on the Wikipedia article Genetic drift, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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