Difference Between Gene Flow and Genetic Drift (With Table)

When a living being (human, animal, or plant) is born they tend to have different features.they have their own characteristics.

These characteristics can be anything like shape of nose or eyes, behavior, any disability, etc. Every person is unique in their own way, but there is resemblance to some extent with their parents or even with their family members like grand parents or siblings.

There is a scientific reason behind such resemblance, this is known as genetic traits. Every living thing has some sort of genes within them which are transmitted to the next generation through the process of reproduction.

Genes are sequences of nucleotides in RNA and DNA which is fused during the process of coitus(sexual intercourse) or pollination in case of plants. Genes determines the hereditary traits of parents to their offsprings.

Reproduction can be done in opposite sexes. So, when a male sperm fuses with a female ovary it carries genes within them and even the female ovary has its own genes and when an offspring is born they tend to have few characteristics of both parents. It is seen that there are less or no chances of complete resemblance this could be because of gene flow. Changes in characteristics can be the result of genetic drift or gene flow.

Gene Flow vs Genetic Drift

The main difference between gene flow and genetic drift is that gene flow is caused by migration of organisms into new different populations while genetic drift is usually the result of reduction of population or a new whole population.


Comparison Table Between Gene Flow and Genetic Drift (in Tabular Form)

Parameters of Comparison

Gene flow

Genetic drift


Caused due to migration

Caused due to random sampling

Chances of changes

Higher chance

Lower chances


Happens only when new genes are entered in a another new population.

Can happen by forming another smaller group from larger population(founder effect).


It does not completely alter the pre existing genes.

It alters pre existing genes.

Impact on next generations

Genes are multiplied in new populations.

Genes can sometimes vanish (bottle effect).


What is Gene Flow?

Gene flow is the transfer or migration of genes or genetic variations.this happens when one population mixes with another population. Gene flow happens when a new set of genes is entered in one population creating a different set of combinations of traits.

When a set of gene fuses with different genes  the more dominating alleles can lead to show more characteristics in offspring.

For example, when an indian boy ( brown skin colour, black hair) migrates to Europe and mates with an European female(blonde hair, white skin colour), their offspring might have characteristics of both parents like black hair and white skin.

And when that mixed gene offspring mates further, it will create another new combination of genes and the cycle will go on. Entering new or foreign genes into one population where those genes did not persist before is known as gene flow. The main cause of gene flow is the migration of organisms or sometimes geographical isolation.

Gene flow is considered healthy for any population from a biological perspective.


What is Genetic Drift?

Genetic drift refers to change in allele frequencies from one generation to the next generation of a population due to several reasons. Genetic drift can be considered as diminishing a set of genetic variations of one generation.

When genetic drift happens it lowers the chances of passing those particular genes to the next generation, which further decreases the chances of migration of those genes.

There are possibly two causes of genetic drift, those are:-

  1. Bottle effect- when a population dies due to some calamity or mishappening.
  2. Founder effect- when within a population a smaller group emerges making their own group.

Genetic drift can lead to vashining one whole type of gene. And leading it to extinction.

For example, dinosaurs are extinct, no other animal has the genes of dinosaurs. It can be classified under bottle effect. Wherein, one kind of population got extinct due to calamity. Now, dinosaurs are no more, nor can take birth, as those genetic characteristics are extinct. It can happen to larger as well as smaller populations. Size  of population does not affect genetic drifting.

It can be understood by one more example, when a disabled man(blind) is married to a normal female, who is out of their family background, and their offspring is normal, so somewhere those genes of disability(blindness) will vanish gradually in further generations.

Main Differences Between Gene Flow and Genetic Drift

  1. Gene flow is caused by migration of alleles from one population to another while genetic drift is caused due to random sampling.
  2. Gene flow happens by moving out of one kind of population, whereas genetic drift can happen within a population in case of founder effect.
  3. There are higher chances of alteration in gene flow as compared to genetic drift.
  4. In gene flow transmission of allele and it’s multiplication in further generation is more likely, on contrary in genetic drift in case of bottle effect genes are diminished in future generations.
  5. In gene flow it does not alter the persisting alleles but in genetic drift it alters  the pre existing alleles.



Gene flow and genetic drift are two different processes, both of them  bringing changes to the future generation. Both can lead to positive and negative changes to society biologically depending on environmental changes.

Gene flow and genetic drift leads to mixed combinations of genes in further generations. Both of them are somewhere the result of moving out of hereditary genes (founder effect in case of genetic drift).


  1. https://www.sciencedirect.com/science/article/pii/0040580977900454
  2. https://onlinelibrary.wiley.com/doi/abs/10.1111/mec.15221