Gene Flow vs Genetic Drift: Difference and Comparison

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

These characteristics include the shape of the nose or eyes, behaviour, disability, etc. Every person is unique in their way, but there is a resemblance to some extent with their parents or even with their family members like grandparents or siblings.

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

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

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 genes when an offspring is born; they tend to have few characteristics of both parents.

Key Takeaways

1. Gene flow is the transfer of genetic material between populations through migration, mating, or the dispersal of gametes, resulting in the sharing of alleles.
2. Genetic drift is the random change in the frequency of alleles within a population due to chance events, such as the survival or reproduction of individuals, which can lead to changes in genetic diversity over time.
3. Both gene flow and genetic drift contribute to the evolution of populations, but gene flow increases genetic variation within populations, while genetic drift can reduce it.

Gene Flow vs Genetic Drift

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

 

Comparison Table

Parameters of Comparison	Gene flow	Genetic drift
Causes	Caused due to migration	Caused due to random sampling
Chances of changes	Higher chance	Lower chances
population	It happens only when new genes are entered into another new population.	This can happen by forming another smaller group from a larger population(founder effect).
Alteration	It does not entirely 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).

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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 into one population, creating a different set of combinations of traits.

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

For example, when an Indian boy ( brown skin colour, black hair) migrates to Europe and mates with a 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 continue. Entering new or foreign genes into one population where those genes did not persist before is known as gene flow.

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

 

What is Genetic Drift?

Genetic drift refers to changes 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, further decreasing 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 a minor group emerges within a population, making its group.

Genetic drift can lead to fashioning 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 the bottle effect.

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 expected, so somewhere those genes of disability(blindness) will vanish gradually in further generations.

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Main Differences Between Gene Flow and Genetic Drift

1. Gene flow is caused by the 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 the case of the founder effect.
3. There are higher chances of gene flow alteration than genetic drift.
4. In gene flow, the transmission of alleles and their multiplication in a further generation is more likely; on the contrary, in genetic drift, in the case of the bottle effect, genes are diminished in future generations.
5. In gene flow, it does not alter the persisting alleles but alters the pre-existing alleles in genetic drift.

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References

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

Last Updated : 11 June, 2023