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Genetic diversity - why?

Genetic diversity - why?

In nature, reproduction is based on the principle of maximum genetic diversity. To achieve this goal, it uses the possibility of constantly reassembling and blending genetic possibilities with sexuality. The optimal genetic diversity is obtained by hard selection of the sexual partners on performance, in terms of fitness and the best possible adaptation of an individual to its environment.

In earlier times, dog breeds were bred exactly to these, basically to nature very close goals. It was selected for specific purposes such as herding, hunting or protecting the house and the yard. And it solidified certain desirable characteristics of engrafting, inbreeding and incest breeding. Thus, the first specialists emerged from the allrounders of the old, freely reproducing dog population.

This selection of the old breeders was very useful and helpful in many cases. The genetic diversity of the breeds was still great and the health of individual individuals was correspondingly good. Added to this was a significant circumstance. The selection of dogs was hard and relentlessly focused on their functionality.
Anyone who was sick or appeared unable to work was killed by the breeder. This factor relentlessly replaced the selection that Mother Nature had previously made. (Killing puppies is of course in our time unacceptable, but it should be mentioned here to illustrate the selection pressure at that time, which had taken the place of natural selection.) Furthermore, then the breeders were free in the decision to incorporate foreign races to improve their breeding results. This, too, brought only advantages to the possibilities of variation by increasing genetic diversity.

Then came a turn. There are many dog ​​breeds today, but hardly any are bred for use. The important factor "usability" as a basis for existence fell away. More and more was selected purely for appearance. Extreme became targets in breeding. The dogs became giants or dwarfs. The hair was either over-bred or completely off-bred. Body shapes and coat colors seemed to become a plaything for the Creator. The health aspect was all too easily undercut, among other things because of the lack of a choice for performance.

Unfortunately, then came the next step, which you can only regret from today's perspective. The breed books were closed. This means that breeders could no longer rely on dogs from other races if they wanted to breed as purebred recognized dogs, which was previously quite common and permissible for the benefit of the respective breed. It should be noted at this point that the breeding books were closed in the 18th century, where the implications for the entire dog breed were not yet understood, because genetics was not yet known as science. Thus, races that
were not previously considered separately were simply split, such as Pinscher and Schnauzer. Even they were no longer allowed to be mixed together.

The once so diverse gene pool was therefore sorted out and split more and more over time. Changing fashions, as well as wars, created new bottlenecks through which the races had to pass. From the former gene lake "mixed breed dog" figuratively speaking, a tub "working breeds" was filtered out of genetic possibilities and turn this tub again only a bucket "show dog genes".

If you now imagine that the genome of today's pedigree dogs - that is, the totality of all hereditary possibilities - each consists of a bucket of building blocks, then you have a good picture. Each of these stones represents at least one, mostly self-contained predisposition and also has an influence on certain other building blocks in the bucket. However, the fewer building blocks are in the bucket, the fewer possible combinations of stones among each other, and the more uniform the result will be. Stones that were once removed from the mass of the contents are irretrievably lost in such a closed system. To this I quote Ms. Professor Sommerfeld-Stur from an article of 10/2014 in the dog magazine WUFF: "... if genes are lost in a closed population, such as a dog breed, it is an irreversible loss, the only way to recover lost genes getting is a cross."

Unfortunately, with every lack of theoretical combination possibility, a whole piece of health is lost. And the danger grows that the stones find themselves together in morbid combinations.

In the past, breeders thought that inbreeding mates could make certain covert diseases visible. Actually, however, it is the fact that by bringing together two equally conceived breeding partners, they brought on a disease that could not have occurred in a partner with a different genetic variation.

Thus, the greater the genetic diversity - the more building blocks in the bucket - the greater the chance that individuals will emerge who can live healthily because their combination of genes does not produce disease. That's why genetic diversity is so important. And that is why it is so important for our dogs to move away from breeding-in any form, be it line breeding, inbreeding or incest breeding, as far as possible, if it is just about egalitarianism in order to achieve the desired exhibition success.

And that's why breeding in foreign races is no longer a faux pas. According to the findings of population genetics, it is no longer allowed to be. Especially not when a dog breed suffers, as the pug does in too many cases of bachycephalic respiratory distress syndrome. In which the pug is based in its worldwide (!) Existence on whole 50 starting animals (no matter where it comes from), as a study of Imperial College in London for the 10,000 pugs in its motherland England occupied - and most likely in 40% of its population simply or double carries the gene mutation for a fatal disease (witch is PDE).