What is Genetic Drift?


Genetic drift is a phenomenon where the frequency of genes in a small population undergoes random fluctuations. Unlike natural selection or mutation, this process does not favor genes that confer advantages in survival or reproduction. Genetic drift is particularly significant in small populations and can lead to a reduction in genetic diversity.

Mechanism of Genetic Drift

Genetic drift occurs through the following steps:

  1. Randomness in Reproduction: Some individuals may, by chance, leave behind more offspring than others, resulting in their genes becoming more common in the next generation.
  2. Population Size: In small populations, gene frequencies can fluctuate significantly, with random effects having a greater impact.

Examples of Genetic Drift

  • Bottleneck Effect: When a large portion of a population dies off due to a disaster, leaving only a small group to rebuild the population, genetic diversity significantly decreases.
  • Founder Effect: When a small group of individuals moves to a new area and establishes a new population, this small group does not fully reflect the genetic diversity of the original population.

Impact of Genetic Drift

Genetic drift can lead to reduced genetic diversity and decreased adaptive capacity, especially in endangered species or small populations in fragmented habitats. Thus, genetic drift is a critical factor affecting the evolution of species.