Question

Bottlenecks and the founder effect are two different types of genetic drift. How do they differ? Provide an example of each

Answer 1

Bottleneck effect occurs when a population's size is reduced for at least one generation due to environmental events such as famines, earthquakes, floods, fires, disease, and droughts or human activities such as genocide and human population planning.

Example- The genetic variation in northern elephant seal have reduced due to bottleneck effect. Hunting reduced thier population size as low as 20 individuals at the end of  19th century. Since then their population has rebounded to 30000 but their genes still carry the marks of this bottleneck.They have much less genetic variation than southern elephant seal which were not hunted intensely.

Founder effect: when small group of individuals separate from its larger population and express the genes that was rare in the original population.

Example:  The Afrikaner population of South Africa is mainly descended from few colony of Dutch immigrants .There is high frequency of gene that causes Huntington's disease in afrikaner population because those original Dutch colonists just happened to carry that gene with unusually high frequency.