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Population bottleneck followed by recovery or extinction. A population bottleneck or genetic bottleneck is a sharp reduction in the size of a population due to environmental events such as famines, earthquakes, floods, fires, disease, and droughts; or human activities such as genocide, speciocide, widespread violence or intentional culling.
Founder effect: The original population (left) could give rise to different founder populations (right). In population genetics, the founder effect is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population.
The founder effect is a special case of a population bottleneck, occurring when a small group in a population splinters off from the original population and forms a new one. The random sample of alleles in the just formed new colony is expected to grossly misrepresent the original population in at least some respects. [ 44 ]
Population genetics is a subfield of genetics that deals with genetic differences within and among populations, and is a part of evolutionary biology.Studies in this branch of biology examine such phenomena as adaptation, speciation, and population structure.
Another possible cause of genetic divergence is the bottleneck effect. The bottleneck effect is when an event, such as a natural disaster, causes a large portion of the population to die. By chance, certain genetic patterns will be overrepresented in the remaining population, which is similar to what happens with the founder effect. [4]
A bottleneck can reduce or eliminate genetic variation from a population. Further drift events after the bottleneck event can also reduce the population's genetic diversity. The lack of diversity created can make the population at risk to other selective pressures. [36] A common example of a population bottleneck is the Northern elephant seal ...
Wahlund effect; Regression toward the mean; Multinomial distribution (Hardy–Weinberg is a trinomial distribution with probabilities (, (), ())) Additive disequilibrium and z statistic; Population genetics; Genetic diversity; Founder effect; Population bottleneck; Genetic drift
This image shows how though successive generations random allele fluctuations, or genetic drift, can lead to the fixation or loss of certain alleles within a population. Similar to the bottleneck effect, the founder's effect can also cause allele fixation. The founder effect occurs when a small founding population is moved to a new area and ...