Could continual inbreeding eventually cleanse an inbred population of its genetic flaws through natural selection?

[emeraldwolf]

I read a snippet of a similar theory, and was wondering there was any truth to it. Supposedly, the genes being expressed through inbreeding that cause genetic disorders would actually eventually be culled through natural selection, and in theory, only more favorable traits would remain.

 

So in the long term, its suggested that inbreeding in the long term could actually yield genetically superior, or at least genetically preferred (since it is all pure blood) specimens.

 

What do you think?

[StringJunky]

I read a snippet of a similar theory, and was wondering there was any truth to it. Supposedly, the genes being expressed through inbreeding that cause genetic disorders would actually eventually be culled through natural selection, and in theory, only more favorable traits would remain.

 

So in the long term, its suggested that inbreeding in the long term could actually yield genetically superior, or at least genetically preferred (since it is all pure blood) specimens.

 

What do you think?

No. If you inbreed sexually reproducing organisms, you increase the probability of detrimental genes being expressed because the pool of available corrective variation reduces with each inbred generation. Ask yourself; where do the good or rectifying genes come from? There is always a cost to genetically breeding for a narrow range of characteristics; the quality of each such generation diminishes. Having worked in the agricultural seed industry as a seed analyst there are only 4 successive generations used, then the breeders start again.

 

B; Original bred stock from scratch to produce C1: Suitable for reusing as seed stock to produce C2: For feed or replanting to produce C3 which is only suitable for feed.

 

Contrary to the article, the greater the genetic diversity the better chance there is that any progeny will survive adverse internal or environmental events.

Edited May 12, 2016 by StringJunky

[MEC1960]

What you've just described is not science. It's farming. We've been doing this for 9000 years. Almost all of our agriculture is based upon the ability to use inbreeding to produce the crop or animal we want.

 

The biggest problem with inbreeding, however, is as StringJunky alluded to - it reduces genetic variation and that limits a species ability to cope with changes. We are able to produce gigantic populations of highly inbred animals (billions of sheep, cows, chickens, pigs) and plants because we control the environmental, food, health and other pressures they would otherwise face, but such a population without our husbandry would quickly disappear.

 

Inbreeding reduces variation and thus one can derive clonal lines (what you call "pure bloods"). This is routinely done in the lab as well as the farm and is useful if you want the reduce variables due to genetics. Genetic disorders can and do arise and persist in these clonal lines and would in any other inbred sexually reproducing organism. The main reason is that mutations occur at a constant rate (humans, like other eukaryotes, have a mutation rate of about ~1.2 x 10^-8 per site per cell division) and these mutations continually introduce new variation. It is also the case that many genetic disorders do not affect reproductive success and thus are "invisible" (or at least difficult to see) to evolution. A disorder such as ALS which arises late in life, often well past child rearing years, can persist because it is not visible to selection.