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SlavicWolf

Genetic variability

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SlavicWolf    4

When a population comes through a bottleneck which results in a drastically decreased variability within the gene pool, does the variability recover through mutations? How fast?

 

Humans generally are highly inbred - I remember reading somewhere that two chimpanzees from the same forest may differ more from each other than the furthest removed human populations. There is also a lot of variation between various human groups - Africans are generally the most diverse and East Asians the least. Ashkenazi Jews are so inbred that they are basically all related to each other as fourth or fifth degree cousins.

 

Cheetahs are so inbred that skin can be transplanted between individuals with no chances of rejection. This of course has drawbacks in form of poor adaptability, very low survival rates for kittens and being more prone to diseases.

 

So how much time does it take for a population to recover from a bottleneck?

Edited by SlavicWolf

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chadn737    156

Its complex and depends on a variety of factors. If the mutation rate is constant, as it is often assumed to be, then its going to be largely a factor of population growth. Non-African groups have lower genetic diversity because of founder effects. Only a subset of the original human population in Africa left to settle Asia, Europe, and eventually the Americas. This can have a similar effect to a population bottleneck, because you are starting again from a much smaller founding population.

 

So with a constant mutation rate, the faster the population growth, the more often new mutations will arise, adding to the genetic diversity. A fascinating result of recent genome sequencing studies has been that with the rapid population growth of the last couple of centuries, many new genetic variants have popped up that did not exist for most of human history.

 

http://www.sciencema...nt/336/6082/740

http://www.sciencema...ent/337/6090/64

http://www.nature.co...ature11690.html

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CharonY    1608

Tightly connected to growth are also weakish selective pressures (and high survival rates) that allow rare variants to persist. One should add that in this context "new" genetic variants indicates existence and persistence in a given population.. They may have well existed transiently before but got lost. I.e. the assumption is that there was not an unbroken line of transmission or that it was below the detection limit of traditional approaches.

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