Some modern aurochs projects claim they carry out selective breeding on a genetic level. In an article from 2017, I outline why I doubt this. First of all, we have every reason to assume that a lot of, or at least some, key wildtype alleles have been lost during the process of domestication. Furthermore, although the full genome of an aurochs has been resolved, the wildtype alleles of this specimen have not been traced down in modern cattle individually so that selective breeding for those alleles would be possible. And lastly, the number of involved loci might be very, very high and the selection would probably be a century-long project.
Another practical problem for "genetic selection" would be genetic linkage. Genes do not get passed on individually, but are inherited via chromosomes. Let us say we have ten key aurochs alleles on ten loci on the same chromosome. Breed A has five of those alleles on the loci 1-5, and mutated (=domestic) alleles on loci 6-10. Breed B the other five alleles on loci 6-10 and mutated alleles on loci 1-5. No matter how you crossbreed those breeds and select the offspring, it will not be possible to unite these ten alleles in one individual, unless you get very lucky with recombination, which is unlikely. This is a descriptive example of course, but it is very likely that in many cases wildtype and domestic alleles are linked on the same chromosome. This could even be a problem for traditional "breeding-back" as it is executed by all modern projects.
Nevertheless, let us ignore those practical obstacles for now and assume that "genetic selection" is feasible. Which animals would be needed in order to unite as much genetic material of the aurochs present in living bovines? A set of primitive European taurine breeds will not be enough in order to seize the maximum potential. Zebus have been shown to share wildtype alleles with the British aurochs whose genome was sequenced that taurine cattle have lost [1]. Therefore, zebus would have to be included in a "genetic selection" project. It is likely, or perhaps very likely, that there are also alleles which taurine cattle lost and are not preserved in zebus, therefore have been lost in cattle altogether. Some of them, however, could be shared by closely related wild bovines, such as the banteng, gaur, yak, or the two bison species. This would have to be tested. Probably also a wider range than just Southern European primitive breeds would be needed in order to seize the genetic potential of taurine cattle. What about Near Eastern cattle, or Asiatic taurine cattle such as the Turano-Mongolian group? It is not unlikely that they have wildtype gene material not found in in European taurine cattle.
Thus, if one really is to carry out a project that tries to get as much genetic material from the aurochs as possible, not only European taurine cattle, but maybe also taurine cattle of other genetic groups, surely zebuine cattle and perhaps even related bovine species would have to be used. I still think such a project is not practically feasible, but it would be interesting "how far" such a project would get to approximate the aurochs. However, it might be a lot easier to recreate a genuine aurochs via CRISPR-Cas9. For my thoughts on what to do with a genetically recreated aurochs, go here.
[1] Orlando et al.: The first aurochs genome reveals the breeding history of British and European cattle. 2015.
And Auroch MtDNA can only be found in Japanese and Korean cattle.
ReplyDeleteMaybe, they just want to select a few aleles like color or horns ?
The genetic background for horn shape and size is not resolved yet, so I doubt they are selecting on it. Colour genetics are to a certain degree. But still the Tauros Project has not published anything that suggests they are truly executing selection for certain genes
DeleteInteresting, I hope several clones from different times and geographic areas or some crispr edited animals can be made soon. Feels like the idea has been floated for ages but there hasn't been much progress.
ReplyDeleteI wonder what the animals will look like. I feel like the current view of the Aurochs might be idealized in a way. For instance, I think the aurochs had "socks" just like the Banteng and Gaur. I base this on the fact that more than a few primitive breeds have this feature and that especially a lot of woodland and savanna bovines species have this. As the aurochs wasn't purely a plains species, I feel it would have had that coloration as well or at least some sub-populations would've had it as there seems to be a genetic trait that shows up in a lot of primitive and not so primitive breeds, from grey cattle, to brown cattle, blonde cattle and even some Iberian breeds.
The light markings seem to help with shape obfuscation in areas where there is lighter dried grass at ground level that hide legs and darker shrubs at body level that camouflage a darker body.
Look at the socks on this Maraichine cow https://www.racesdefrance.fr/bovins/tres-faible-effectif?id=240.
This breed and other related breeds (Nantaise & Parthenaise) are reportedly descended from Dutch cows that were adapted to marshy conditions (the Netherlands was very marshy and swampy before being cultivated). But, they probably were brought to France at a time before pied and uniformly colored animals became favored in the Netherlands. The Netherlands was filled with cattle herders and breeders since ancient days, as was commented on by the Romans and historians. Maybe this breed has some old norther-west European aurochs genes that got preserved in the breed? The breed name comes from French word Marais, which is related to the Dutch and English words Moeras and Morass, meaning swamp.
It has been theorized that before human intervention Aurochs habitat was concentrated around grassy meadows and savanna type landscapes of river floodplains, which would also include swampy areas. Maybe some genes were preserved in populations of cattle that needed to deal with those conditions.
Maybe some of those genepools, like for instance the Maraichine should be added to breeding back programs to get a more complete and varied gene pool that doesn't overly focuses on Iberian/Mediterranean breeds?
The Aurochs:
ReplyDeletehttps://www.youtube.com/watch?v=RmRs31tJn7s
Some Animals destroyed by Civilization:
ReplyDeletehttps://prehistoric-fauna.com/Animals-destroyed-by-Civilization