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Genetic Drift: Inroduction, Examples, Types, Causes

Genetic drift refers to random changes in the frequency of alleles (different versions of a gene) in a population. Check this article to know more about the Genetic drift.
authorImageJasdeep Bhatia13 Jun, 2024
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Genetic Drift

If you are looking for Genetic Drift, you have come to the right place!

The topic “Genetic Drift” will be covered in this article. Gene variants, or alleles, can be chosen if they benefit or disadvantage an organism, while some changes may have no impact. Genetic drift affects an allele when it is not the allele itself changing its frequency in a population. The graph below depicts various time courses for the same genes. As you can see, these genes' frequency can fluctuate significantly over time, particularly in the smallest populations. The allele frequency of each gene is steady mainly in the largest populations. This occurs because no natural selection pressure exists for or against the allele. After all, genes do not affect fitness. Even in the smallest groups, these genes' frequencies might vary significantly. This article will discuss the genetic draft's examples, types, causes, consequences, and key facts.

Genetic Code

Introduction

Genetic drift, sometimes referred to as allelic drift or the Wright effect, is the change in a population's frequency of an existing gene variant (allele) brought on by random chance. Genetic variety may be hampered by genetic drift, which may cause gene variations to disappear completely. Moreover, it can make previously uncommon alleles far more common and even fixed. The effect of genetic drift varies based on the number of copies of an allele present, from more to less noticeable. Intense debates surrounded the relative importance of neutral mechanisms, such as genetic drift, versus natural selection in the middle of the 20th century. Ronald Fisher, who used Mendelian genetics to explain natural selection, believed that genetic drift had a minimal influence on evolution. This idea predominated for several years.

Gene Flow

Examples of Genetic Drift

Some examples of genetic drift's examples are listed below for a better understanding of the phenomenon.
  • Children with brown or blue eyes can come from any parent with both blue and brown eyes. However, if the brown eye colour is the dominant allele, there may be a chance that the offspring will only have brown eyes in the future and that the same eye colour will be passed down through the generations, rendering the genes for blue eyes recessive.
  • Now let's use the illustration of the bunnies. The dominant gene in rabbits with brown and white fur is white. However, the dominant allele will be impacted by genetic drift, and only the brown population may survive, wiping out the white-furred rabbits.
  • The American bison is yet another illustration. Its population was previously so heavily hunted that it was in peril. Yet according to the experts, the returned population now lacks sufficient genetic diversity.
  • A bird with two different beak sizes as an allele. Hence, genetic drift may affect the size of the bird's beak by eradicating a particular beak size from the natural world, thereby lowering the bird's genetic diversity.

Genetic Code Codons Amino Acids

Types of Genetic Drift

Population Bottleneck

A population's size drastically declines due to genetic drift, known as a population bottleneck. These drastic population reductions are caused by competition, illness, or predation. The organisms that survived now decide the allele pool. Because they are the sole remaining alleles, some alleles experience increased frequency. When people don't finish their antibiotic treatment, there can be this kind of genetic drift. Regardless of the alleles they carry, dangerous bacteria in your system are killed by antibiotics. Injurious bacteria drastically decrease as a result of antibiotic use. This eliminates illness symptoms. Only a small population will live if a patient stops taking an antibiotic too soon. The allele frequencies in this much smaller population may differ considerably from those in the bacteria's initial population.

Gene Therapy

Founder Affect

A new population is established, or "founded," in a new site in the founder effect, a different sort of genetic drift. The allele frequencies in this population will differ greatly from the parent population if it does not interact and procreate with the main population. Because of the founder effect, many islands have species that are island-specific. For instance, if only two species of birds arrive on an island, their alleles will explain the variety there. Although these alleles initially predominate, population mutations will eventually result in new adaptations. The original population continues to use this new adaptation. The two groups have the potential to become so different over time that they are unable to interbreed. This is a common method in that species diverge.

Ganongs Potometer

Causes of Genetic Drift

Smaller species populations are considerably more likely to experience genetic drift. The graph's lines depict the frequency of alleles in a particular population. Any allele can soon become fixed or extinct when there are many alleles and a small population. There is a lower likelihood of losing a whole gene when numerous creatures are in the population, as many organisms carry the allele. It is less likely that they would all go extinct. It is simple to mix up genetic drift and natural selection. Whether an allele actively contributes to the shift in frequencies makes a difference. The frequency of an allele will rise if it affects an organism, which leads to greater DNA replication. It will decrease if it causes harm. The direct effects of the allele on the organism and environment are the cause of this. Natural selection is at work here. Genetic drift occurs when the allele changes merely because it was present in the unrelated species that survived.

Gastric Symptoms

Consequences of Genetic Drift

Genetic causes a loss of genetic variety wherein the fixation of some genes may be comparable to their initial frequency in the population. Another effect of genetic drifting is the rise in population differentiation, where different populations of the same species may have different alleles due to genetic drifting. This happens when one allele's frequency is fixed in one population while decreasing in another because allele frequencies in the genetic pool move in different directions. Small populations' allele frequencies can shift more due to sampling error than big populations. Since the gene pool of big populations tends to be more stable, alleles are fixed more quickly in large populations than in small ones. However, large populations are impacted by genetic drift because they shrink as a result of a natural disaster that drastically reduces the population size until the situation improves to allow the population to grow again (bottleneck effect) or when a small population abandons the group to found a new colony when the population is in danger (founder effect).

Difference Between DNA and RNA

Key Facts About Genetic Drift

  • Genetic drift is typically considered an arbitrary alteration in a population's genes with significant future implications for the wider population.
  • If genetic drift occurs, it has the potential to have a profound effect on the population. Future generations will be able to see the effects of genetic drift.
  • It can damage plants, people, and animals but only has a little effect on the overall population.
  • Errors in the DNA or allele selection from the gene pool typically cause genetic drift.
  • Although the environment does not play a role in the incidence of genetic drift, it does play a role in the emergence of a new type of dominant species in a habitat that may serve as a habitat for an invading - alien species.
  • The entire ecosystem and habitat could be severely hampered by genetic drift and invading alien species.
  • The weaker allele is naturally eliminated by the population, a characteristic of the bottleneck effect.
  • A new population appears in a new area due to the foundation effect's unique habitat or physical or geographic barriers.

Genetic Drift <span style=

Q1. What circumstances favour genetic drift?

Ans: Genetic drift is a random process that can produce significant population changes quickly. Regularly tiny population numbers, drastic population size reductions known as "bottlenecks," and founder events where a new population is created from a small number of individuals are all factors that contribute to random drift.

Q2. What circumstances are most likely to result in genetic drift?

Ans: Seldom occurring alleles are more likely to be lost in small populations, where genetic drift typically occurs. Genetic drift will persist once it starts until the relevant allele is either lost by a population or until it is the only allele present in a population at a specific locus.

Q3. Will evolution always be the product of genetic drift?

Ans: Contrary to natural selection, genetic drift has an entirely random impact on the population's genetic composition. As genetic drift is an evolutionary mechanism, adaptations do not result from it.

Q4. Does mass extinction result from genetic drift?

Ans: Both inbreeding and drift decrease genetic diversity, which has been linked to a higher risk of population extinction, a slower rate of population growth, a decreased capacity to adapt to environmental change, and a decreased capacity for disease resistance, all of which affect the ability of individuals who have been released to the wild to survive.

Q5. How does genetic drift impact pregnancy rates?

Ans: Genetic drift is a phenomenon that causes allele frequencies in a population to shift haphazardly from one generation to the next. This occurs due to a population's varying reproductive success; some members have a higher birth rate than others.
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