Summary
Loss of genetic diversity after a few individuals found a new population or numbers crash.
In depth
The sample of alleles in a few colonists or survivors is unrepresentative; rare alleles may be common or lost. Reduced diversity makes populations vulnerable.
Northern elephant seals fell to about 20 individuals in the 1890s and have very low genetic diversity today.
Founder effects explain high frequencies of rare diseases in isolated groups: Ellis-van Creveld syndrome among the Old Order Amish in Pennsylvania from a single founder couple, or Huntington disease in Lake Maracaibo, Venezuela. Bottlenecks reduce diversity: cheetahs went through one about 10,000 years ago, so individuals are so similar that skin grafts are accepted between unrelated animals.
Consequences include loss of rare alleles, inbreeding depression and reduced adaptive potential. Conservation uses genetic rescue and managed breeding to restore diversity, as with the Florida panther and the Mauritius kestrel. Human populations show reduced diversity farther from Africa, a result of serial founder events.
Remember: both are types of genetic drift, caused by chance sampling of alleles.
Frequently asked questions
What is Founder Effect and Bottleneck?
Loss of genetic diversity after a few individuals found a new population or numbers crash.
Which area of biology covers Founder Effect and Bottleneck, and how advanced is it?
Founder Effect and Bottleneck is one of the 53 topics in Evolution. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Allopatric Speciation, Speciation, Mass Extinctions.
Can you give an example of Founder Effect and Bottleneck?
Cheetahs have a similar genetic uniformity from a past bottleneck.
What should I learn before Founder Effect and Bottleneck?
Work through the Beginner topics in Evolution first, such as Evolution, Natural Selection, Charles Darwin, then return to Founder Effect and Bottleneck. Advanced topics assume the Intermediate vocabulary.
What topics are related to Founder Effect and Bottleneck?
The closest topics to Founder Effect and Bottleneck are Allopatric Speciation, Speciation, Mass Extinctions, Ancient DNA. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Founder Effect and Bottleneck?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Founder Effect and Bottleneck. To practise the whole of Evolution, use the Evolution quiz.
How is Founder Effect and Bottleneck different from Allopatric Speciation?
Founder Effect and Bottleneck: Loss of genetic diversity after a few individuals found a new population or numbers crash. Allopatric Speciation: Speciation after a geographic barrier separates populations, as with Darwin's finches on separate islands. Read both side by side and note what each one explains.
How should I study Founder Effect and Bottleneck step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Allopatric Speciation and explain the difference aloud. Finally, take the Evolution quiz and come back to this page for any question you miss.