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Posts Tagged ‘population genetics’

Jess at DesertWindHounds discusses the importance off genetic diversity in the Major Histocompatibility Complex (MHC),  a gene family that controls immune responses. In dogs, it’s called the Dog Leukocyte Antigen (DLA) system

It’s very important that everyone in dogs understands these concepts.

In fact, it’s very important that everyone interested in conservation of endangered species or in breeding any kind of animal has a full grasp of the problems that can happen with reduced diversity in the MHC.

This angelfish website also partly discusses the MHC. Unlike Jess’s post, it is pro-inbreeding, but the author recognizes the need to bring new blood in.

The problem with dogs is we are operating within a closed registry or a Potemkin open registry system where new blood is not easily brought in.

And with virtually all Western breeds, all individuals within a breed are derived from the same founders.

The is the big problem with line-breeding, inbreeding, and using just a few sires  per generation within a closed registry system. At some point, the breed becomes too homozygous within the MHC/DLA, and it’s screwed when a really bad disease pops up.

My guess is we’re going to hear a lot about the MHC in the near future. Many success stories of recovering endangered species are going to turn into disasters.  Some species have recovered from a very low founding population, and that means that they don’t have much variation at all in their MHC.

That’s bad.

And there is one animal right now that recovered from intense persecution in its homeland. It was eventally protected, and its numbers grew.

But now because of a communicable disease, it may very well go extinct. As a species, it has low genetic diversity and very little variation in the MHC. If it does become extinct, it will be this compromised genetic diversity that ultimately does it in. If it had more diversity in its MHC, then some individuals might have a some immunity to it, but thus far, all have been found to be highly susceptible to this disease.

I’ll reveal that animal and its disease  tomorrow in a longer post.

Until then, read this post and get a good understanding of what the issues are.

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