Genetic Drift Examples to Know for Evolutionary Biology

Genetic drift plays a crucial role in shaping populations and their evolution. It highlights how random events can significantly impact genetic diversity, especially in small groups, leading to unique evolutionary paths and potential challenges for survival and adaptability.

1. Founder effect

   • Occurs when a small group of individuals establishes a new population.
   • The genetic makeup of the new population may differ significantly from the original population.
   • Can lead to increased prevalence of certain alleles, potentially causing reduced genetic diversity.

2. Population bottleneck

   • A sharp reduction in population size due to environmental events or human activities.
   • Results in a loss of genetic variation as only a few individuals contribute to the gene pool.
   • Can lead to inbreeding and increased susceptibility to diseases.

3. Small population size

   • Smaller populations are more susceptible to genetic drift due to random fluctuations in allele frequencies.
   • Increased likelihood of allele fixation or loss, which can affect evolutionary potential.
   • Can result in reduced adaptability to changing environments.

4. Neutral mutations

   • Mutations that do not affect an organism's fitness and are not subject to natural selection.
   • Can accumulate over time and contribute to genetic variation within a population.
   • Their spread in a population is primarily influenced by genetic drift.

5. Genetic hitchhiking

   • Occurs when an allele increases in frequency not because of its own advantage, but due to its association with a beneficial allele.
   • Can lead to the spread of neutral or even deleterious alleles in a population.
   • Highlights the interconnectedness of genetic traits and their evolutionary implications.

6. Allele fixation

   • The process by which a particular allele becomes the only variant in a population.
   • Can occur through genetic drift, especially in small populations.
   • Results in reduced genetic diversity and can limit future evolutionary options.

7. Loss of genetic diversity

   • A decrease in the variety of genetic traits within a population.
   • Can result from founder effects, bottlenecks, and small population sizes.
   • Reduces a population's ability to adapt to environmental changes and increases extinction risk.

8. Random sampling of gametes

   • The process by which alleles are randomly selected during reproduction.
   • Can lead to fluctuations in allele frequencies from one generation to the next.
   • Contributes to genetic drift, especially in small populations.

9. Genetic drift in island populations

   • Island populations often experience genetic drift due to isolation and small size.
   • Can lead to unique evolutionary paths and distinct genetic traits.
   • Increases the risk of inbreeding and loss of genetic diversity.

10. Cheetah population bottleneck

    • Cheetahs experienced a severe population bottleneck around 10,000 years ago, reducing genetic diversity.
    • Current populations show high levels of inbreeding and low genetic variation.
    • This bottleneck has implications for their adaptability and long-term survival.