Question

a. Explain how genetic drift can lead to a reduction in the genetic variation within a population. 

b. Under what conditions is drift most likely to occur?

Answer 1

a) Genetic drift can lead to a reduction in the genetic variation within a population.

Genetic drift leads to random changes in allele frequencies. Drift causes fixation of alleles. When an allele reaches a frequency of 1, it is said to be fixed in a population, and when an allele reaches a frequency of 0, it is lost.

​​​​​​​​​​​​Once an allele becomes fixed, genetic drift comes to a halt, and the allele frequency cannot change unless a new allele is introduced in the population via mutation or gene flow.

Thus even while genetic drift is random, directionless process, it acts to eliminate genetic variation over time.

b) Conditions under which drift is most likely to occur are:

Small population- genetic drift can be a major driving force for changing allele frequencies in small populations. The smaller the population, the more extreme it tend to be.

Also drift is likely to occur randomly in a population through sudden disasters such as floods, earthquakes, fires, etc. It usually wipes out a portion of the population at random and the resulting members of the population have a different allele frequency as a result.

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