Question

 

1 What is genetic drift?  

2 In what way can a genetic bottleneck lead to genetic drift in population?

3 In what way can founder effect lead to genetic drift in a population?

Answer 1

 

1).

• Genetic drift is the evolution where a change in the allele frequencies of a population occur over generations as a result of chance events or sampling error.
• Genetic drifts results in random, unbiased changes overtime in the frequencies of alleles in a population
• It is also known as Sewall Wright effect, named on it's founder.
• Genetic drifts can occur in any populations size but it's effects are more strongly visible in small populations.
• Some times genetic drifts may lead to loss of some alleles whereas in some conditions it may increase the frequency of alleles upto 100%.
• Unlike natural selection, genetic drift doesn't concern about the nature of an allele in an individual i.e. whether an allele is harmful or beneficial, it will still be subject to the chance events.
• Among other factors such as mutation, migration and natural selection, genetic drift is one factor which causes the changes in gene pools over time.
• Several recent theory of evolution considered genetic drift as a key factor of evolution.

2). Bottleneck effect on genetic drift;

• It is an example of happening of genetic drifts within the population of severely small size.
• It may happen due to any natural disaster such as an earthquake or flood which can annhilate a population, killing most members of the population and leaving only a small group of survivors.
• Those survivors are choosen on a random basis by chance event without any bias in their sampling.
• In such groups, frequencies of allels vary from the original population and there may be permanent loss of some of the alleles.
• Somtimes bottleneck effect leads to a decrease in the genetic diversity of an ecosystem.
• In the bottleneck effect, the genetic composition of remaining random survivors represent the genetic composition of the entire population.

3). Founder effect;

• It is also another example of extreme genetic drift, which occurs as a result of an attempted coup in a popultion i.e.a small group may establish a seperate colony by breaking from the original population.
• Due to seperate formation of new colony, members of this new colony may not represent the genetic diversity of original population.
• The alleles in this new colony are distributed throughout the population at a frequency different then the original population.
• There may also be a risk of missing of some alleles throughout the new group.
• Concept of founder effect is somewhat similar to the bottleneck event only differing in their mechanisms.

• So, it can be said that genetic drift is an important point for evolution of some species.
• Every populaton, at any point of time experience the genetic drift but small populations are affected more.
• Genetic drift does not offer any kind of bias selection to the entire population.