Question

What is meant by genetic drift? Explain genetic drift citing the example of founder effect.

Answer 1

• Genetic drift is a change in the gene pool of a small population that takes place strictly by chance.
  
• Genetic drift is also called genetic sampling error or Sewall Wright effect,
• There are two major types of genetic drift. They are bottlenecks and founder effects.
• The founder effect is one that occurs when a small group of individuals breaks off from a larger population to establish a colony. The new colony is isolated from the original population, and the founding individuals may not represent the full genetic diversity of the original population. That is, alleles in the founding population may be present at different frequencies than in the original population, and some alleles may be missing altogether.
  
• For example, the Afrikaner population of Dutch settlers in South Africa is descended mainly from a few colonists. Today, the Afrikaner population has an unusually high frequency of the gene that causes Huntington's disease, because those original Dutch colonists just happened to carry that gene with unusually high frequency. This effect is easy to recognize in genetic diseases, but of course, the frequencies of all sorts of genes are affected by founder events.