Question

There are two types of genetic drift. Describe and give an example of both the bottle neck effect and the founder effect.

Your assignment should be 250-500 words in length.

Answer 1

Genetic Drift:

• Genetic drift is also known as Allelic Drift. It is also known as Sewall Wright Effect as it is given by the biologist Sewall Wright.
• It is change in the frequency of existing allele in a population due to random sampling of organisms.
• Genetic Drift causes gene variants to dissappear completely and reduces genetic variations.

Genetic Drift is of two types. They are Bottleneck effect and Founder effect.

Bottleneck effect :

• Bottleneck or Genetic Bottle neck effect is a sharp reduction in the size of the population because of various environmental effects like earthquake,flood,fires,droughts and contagious diseases or any other human activites.
• These environmental effects reduces the genetic pool variations of a population.
• And hence corresponds to smaller genetic diversity. This diversity pass on genes to further generation, to their offsprings through sexual reproduction.
• As a result the ability of population to adapt and survive to the enivornmental changes like climate or variations in the available resources are reduced.
• Population bottleneck effect will change the proportional distribution of alleles by chance and leads to the fixation or loss of alleles.
• Population bottleneck effect plays an important role in conservation biology that it maintains minimum viable population size and also biological and pest control.
• Example: Northern Elephant Seals have reduced genetic variation because of Population bottleneck effect. Hunting reduced their population size to as few as 20 individuals.

Founder effect:

• Founder effect can be defined as loss of genetic variation that occurs when a new population is established by very small number of individuals from a larger population.
• Due to the loss of genetic variation, new population may have distinctly different both genotypically and phenotypically from the parent population from which it is obtained.
• Founder effect leads to the speciation and subsequent evolution of new species.
• A population bottleneck effect may also cause a founder effect though it is not strictly a new population.
• Founder effect occurs when a small group of migrands that is not genetically representative of population from which they established a new area.
• Population obtained as a result of the founder effect shows increased sensitivity toi genetic drift and an increase in inbreeding and a low genetic variation.
• Example: Generally a founder effect occurs when a new population is started by few members of original population.