Microevolution (evolution on a small-scale) refers to the changes in allele frequencies within a single population. Allele frequencies in a population may change due to four fundamental forces of evolution: Natural Selection, Genetic Drift, Mutations and Gene Flow. Citation: Andrews, C. A. Natural Selection, Genetic Drift, and Gene Flow Do Not Act in Isolation in Natural Populations. Nature Education Knowledge. Genetic drift is the changes in allele frequency in a gene pool. The bottleneck effect and founder effect are prime examples of genetic drift. Genetic drift is the changes in allele frequency in a population. Gene flow is the proccess of alleles moving from one population to is the only differenetic driftence between gene flow and.


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It happens when a population migrates or becomes geographically isolated.

This is different from the genetic drift seen with the founder effect where the new group is formed in an area that does not have an existing population. Also, natural selection is influenced by changes in environmental conditions while genetic drift is random and based on luck.

Allele is defined as any one of two or more genes that may occur alternatively at a given site locus on a chromosome. Alleles are responsible for variations in a trait. The population bottleneck and a founder effect are two examples of random drift gene flow and genetic drift can have significant effects in small populations.

Genetic drift works on all mutations and can eventually contribute to the creation of a new species by means of the accumulation of non-adaptive mutations that can facilitate population subdivision.

Genetic Drift vs. Gene Flow vs. Natural Selection

It is a random event, in which some genes there is not any distinction are extinguished from the population. This results in a drastic reduction of the total genetic diversity of the gene flow and genetic drift gene pool. The small surviving population is considerably be farther from the original one in its genetic makeup.

Founder effect is gene flow and genetic drift loss of genetic variation that occurs when a new population is established by a small number of individuals that are cleaved from a larger population. This new population does not have the genetic diversity of the previous one.

Because the community is very small and also geographical or socially isolated, some genetic traits are becoming more prevalent in the population.

gene flow and genetic drift This leads to the presence of certain genetic diseases in the next generations. In some cases, founder effect plays a fundamental role in the emergence of new species.

The frequency of alleles in the population is the same. Randomly and due to a catastrophic natural or man-made event, most of individuals of the population died there is no influence of adaptive pressures.

Mechanisms of Evolutionary Change | Nectunt

As a result, the original large population is reduced to a small population composed by few individuals. This new surviving population subset contains much less genetic variability than the previous population. Later, the drastic reduction in the gene flow and genetic drift size is followed by an expansion population is recovered.

The final population is no longer genetically representative of the original one. In this particular case, an allele is completely removed from the gene pool.


A new population is established by a small number of individuals that are cleaved from the original gene flow and genetic drift.

This leads to a loss of genetic variability as the founders of the new colony are not genetically representative at all of the population from which they come from. The right figure shows an evident predominance of orange circles in the newly founded population.

A Quick Genetic Drift Vs. Gene Flow Vs. Natural Selection Comparison

These gene flow and genetic drift circles may correspond to a given allele responsible for the variation in a trait for example, specific eyes color. Gene flow can be an important source of genetic variation when unique genetic information from one population is introduced into a different population.

Gene flow can be caused by many different events. Source In a bottleneck event, a population goes through an event where only a few random individuals survive.