What is the Difference Between Natural Selection and Genetic Drift?

The main difference between natural selection and genetic drift lies in the mechanisms driving changes in allele frequencies within a population over time.

Natural Selection:

Occurs when some forms of a particular gene (alleles) within a population are more successful at surviving and reproducing than other forms in a given environment.
Influenced by changes in environmental conditions.
Responsible for positive changes or adaptations within a population.

Genetic Drift:

Occurs when the population size is limited, and by chance, certain alleles increase or decrease in frequency, leading to a shift away from Hardy-Weinberg equilibrium (HWE).
Changes in allele frequencies are random and not influenced by environmental conditions.
Rarely produces adaptations to the environment.

In summary, natural selection is an evolutionary mechanism driven by the environment, leading to the spread of advantageous alleles within a population, while genetic drift is a random process that can affect allele frequencies in both large and small populations, without necessarily leading to adaptations. Both mechanisms contribute to changes in allele frequencies over time, but they act through different processes and can have distinct outcomes in terms of population adaptation to environmental conditions.

On this page

What is the Difference Between Natural Selection and Genetic Drift?

Comparative Table: Natural Selection vs Genetic Drift

Here is a table comparing the differences between natural selection and genetic drift:

Feature	Natural Selection	Genetic Drift
Definition	A process through which adaptations arise in organisms to allow them to better survive in their environment and reproduce.	Change in allele frequencies in a population from generation to generation due to random chance events.
Driven By	Differential reproductive success of individuals.	Random sampling, such as natural disasters or random mating.
Effect on Gene Pool	Changes gene pool and traits within the population over successive generations through selection pressures.	Changes allele frequencies within a population due to random sampling, sometimes resulting in a decrease in genetic variation.
Population Size	Can occur in populations of all sizes, but its effects tend to be stronger in small populations.	Occurs in populations of all sizes, but its effects tend to be stronger in small populations.
Examples	A stronger, faster male gorilla produces more offspring because he is better suited to compete for resources, leading to the propagation of his genes in the population.	A natural disaster kills a random sample of the population, leading to a change in allele frequencies within the remaining population due to random chance.

In summary, natural selection is driven by the differential reproductive success of individuals, leading to changes in the gene pool and traits within a population over time. On the other hand, genetic drift is driven by random chance events, leading to changes in allele frequencies within a population without consideration of the adaptive value of the traits.

Guilherme Mazui

Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.