Question

Write a note on "Genetic drift".

Answer 1

Genetic drift ( Sewall wright effect)

Random change of gene in a population merely by chnace is called genetic drift. It operates rapidly in small population. Founder effect and bottleneck effect are two forms of genetic drift

1) Founder effect:

When a section of population get isolated or migrated or drifted from original population, than this section becomes genetically different from original population due to change in allelic frequency because gene pool of this section may contain some alleles in a very low frequency or may lack a few alleles. Sometimes the change in allelic frequency is so different in the new population that they become a new species. The original drifted population becomes founders and the effect is aclled founder effect.

2) Bottleneck effect:

Bottlenecks are the natural calamities like earthquakes, floods,volcanic eruptions, storms etc,. A sudden change in the environment may drastically reduce the size of population and now this population may be genetically different from the original population. Certain alleles may have more frequency among the survivors, others may be less and some may be absent altogether.