What is genetic drift?

Genetic drift refers to random changes in allele frequencies within a population over time. This process is a key mechanism of evolution, particularly in small populations where chance events can have a significant impact on which alleles are passed on to the next generation. Unlike natural selection, which involves differential survival and reproduction based on advantageous traits, genetic drift occurs due to random sampling effects.

For instance, if a natural disaster randomly eliminates a large portion of a population, the alleles present in the surviving individuals may not represent the original population's genetic makeup. As a result, certain alleles may become more or less common purely by chance. This can lead to a reduction in genetic diversity and can have significant effects on the evolution of a population over time.

Understanding genetic drift is crucial because it highlights the randomness involved in evolutionary processes and contrasts it with the more deterministic nature of natural selection.