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Sunday, 8 March 2015

Cloning as a chance for the Wisent


As everybody should know, the extremely low diversity of the contemporary gene pool of the Wisent after the severe bottleneck event during the 1920s and 30s is the most immediate danger for the species’ long-term existence. In this post I outlined how the high degree of inbreeding affects the health and fertility of the global population. I proposed careful, controlled introgression of the American bison as a probable way to add more genetic diversity and resistance to diseases without affecting looks, behaviour and ecology of the Wisent too much, documented in an own breeding book.



When writing my post on extinct species that might one day be revived throughcloning, I came up with another idea helping the Wisent to get out of its genetic misère.   

A well-preserved bone from the early Holocene made it possible to fully sequence the genome of a 9,000 years old aurochs bull. If this is possible, it must be feasible to do the same with the genome of an ancient Wisent. There must be plenty of well-preserved Wisent bones or even soft tissues from early Holocene to the 19th century onwards. Turf remains for example. Even more promising might be remains from historic times, such as hunting trophies in form of skulls and skins.

Once a full genome is recovered, either a complete set of chromosomes could be reconstructed (for which, as far as I know, the technique has not been developed yet), or the genome of a living Wisent could be used as a template and edited according to the ancient nucleotide sequence by genome editing. The latter method should be easier and more feasible. I think that there is a good chance to recover the whole genome of not only one but several ancient Wisents. Acquiring a surrogate would be no problem of course. Any specimen that lived prior to the bottleneck event would be a precious gain of diversity, and five individuals or so might even multiply it. You might be wondering how a small group of Wisent should distribute their genetic material on the whole global population. But one and the same individual can be cloned several times. Cloning as many as possible individuals, both bulls and cows, and adding them to herds in various regions. But adding only bulls, or replacing as much inbreed bulls with cloned bulls as possible would not be ideal in my opinion. The Y types of the cloned individuals have to be added to the population, but should not replace the old ones.



One of the advantages of cloning pre-bottleneck Wisents over the cloning of extinct species is that people won’t raise those annoying “ethical” non-issues and they will see the good in it more immediately than in cloning aurochs, Quagga and so on.

Even better: if it succeeds, those cloned wisents could serve as flagships for the good in cloning ancient animals that might help to get public acceptance.



Maybe the idea of cloning “ancient” wisent as a genetic long-term solution for the conservation of the wisent sounds unconventional. And yes, I am fully aware of the fact that it would face the same general problems of cloning just as any other project does (although, as far as my knowledge does, the offspring of cloned ancient wisents and modern ones would have the developmental problems clones have to a much lesser extent). But if we are honest, this concept is the only way to considerably increase the genetic diversity of the Wisent and therefore to solve its major threat as a species, without affecting its genetic integrity by crossing-in another species.

If you agree with me, feel free to spread this idea. I really hope that people who have the right connections are going to see this and maybe such a project might be realized in near future.

6 comments:

  1. I would recommend people contacting the Revive & Restore initiative, which specifically looks to help species in need of genetic assistance through CRISPR technology and/or cloning. http://longnow.org/revive/candidates/

    CRISPR could and should also be used within the aurochs and quagga back-breeding programs to speed up the process and create animals that match the aurochs/quagga not just in phenotype but in genotype as well.

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  2. In India recently they anounced that they succeeded in cloning a bull (from a living bull) and then when the clone was mature used it to breed to a non cloned dam. The result was that the first birth of a calf from a cloned father. Currently two others are pregnant and yet to calve.

    A note on cloning, the only successful clonings without fast deaths come from living young animals. So freshness and vitality of DNA is a must. If you want to do this for Wisent then you need extreamly well preserved DNA from a bull or heifer that died young and healthy. Finding such DNA would be difficult and cloning from old DNA did not work out well when tried previously with a now extinct Deer in Spain at the turn of the Century.

    Currently whilst we are experimenting with artificial chromosomes to provide desired genes in addition to what someone has for example HAC (Human artificial chromosome), it would not be a heritable gene due to no recombination posibilities. There is no direct to chromosome edit technique only the plug in technique.

    Your best chance is a straight up clone attempt and pray the animal lives long enough for sperm to be produced in the case of a male or eggs to be harvested in the case of a female. It is unknown if clone eggs or semen would be more complete then the clone in itself in regards to ancient clones. Further clones should be kept seperate from the main population until full analysis of the clone lifecycle and progeny of clone life cycle are examined. If all is ok then cattle techniques of frozen semen can allow the spred of new genes back into different populations.

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  3. I believe "cloning as many as possible individuals, both bulls and cows, and adding them to herds in various regions" is an awful waste of resources. How many won't reproduce at all, dying early or just being omega male/female?

    A better use of clones would be keeping males in a breeding center where a frozen semen bank would be building up. Then, via artificial insemination, supply the current facilities which keep captive wisent populations to make up to 25% of the births this way. Finally,send the "50% new and 50% ancient DNA" wisents to the wild herds to beef up existing wild wisent population. Of course, about half of the mixed ones will be keep in captivity to strengthen the DNA diversity of the captive wisent population as well.

    Using this method, with just a few clones, you can get hundreds of thousands direct offspring over decades.

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    Replies
    1. Apart from the fact that I doubt that "omega animals" are determined by genetics or apply to bovine social structure in this strict sense at al, your concept sounds way better than mine. Thanks.

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    2. I'm glad you liked my version, although it rely mainly on ancient males. If we are to add genetic diversity for the mitochondria, your massive cloning plan is about the only solution. Except that I would keep the female clones among the captive wisents and send the half and half generation into the wild.

      The omega image may be a bit off, but there are always at least a few males who won't succeed to reproduce at all or very little, which in the end give no impact on the population. Those fancy clones being pricey, better reduce the risk.

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    3. Those males which would not succeed in compeeting with other males (again, I don't know if such exist in bovines) would be able to produce offspring in captive herds because zoos usually use only one breeding bull. Those few "mating inferiority" genes would be an acceptable price for the diversity they would add, IMO.
      Most of the breeding would be done in captivity anyway, as, logically, the vast majority of wisents live in captivity and it probably would be vise to see which impact breeding with clones has under controlled circumstances. But of course, any wisent in the wild is a good wisent. ;-)

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