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Saturday, 1 June 2013

The various breeding-back efforts


There several breeding-back efforts concerning a number of species. Some are well-known and widely publicized, others are not. While some breeding-back results have a history of several decades, others are incipient since their project started only some years ago. In this post I am going to give an overview over the three species the most breeding-back efforts focus on. The history of breeding-back started in the 1920ies, when two zoo directors tried to revive the Aurochs that died out in 1627, although the polish zoologist Feliks Pawel Jarocki had a similar idea back in 1835 [1].

For readers who are familiar with breeding-back, this overview probably isn't anything new, but I want to show the main projects or breeds this blog is going to focus on. 

The Aurochs

Skeleton of an Aurochs bull from Germany (Image source: aueroxen.com)














There are multiple breeding-back efforts to reconstruct the (european) Aurochs, Bos primigenius primigenius. It was the first extinct species (actually, wild type of a species) to become the focus of a breeding-back effort – the well-known experiment of the brothers Heinz and Lutz Heck back in the 1920s, which will be the focus of another post. The result, Heck cattle, was considered to be a “new aurochs” by the Heck brothers and their followers, and is still by some breeders today [2]. However, this breed has been criticized early on and is in fact rather different from the aurochs in several aspects [1]. To improve the aurochs-likeness of some Heck cattle herds, the Arbeitsgemeinschaft Biologischer Umweltschutz (ABU) in Germany started to cross them with several aurochs-like breeds in 1996, such as Sayaguesa or the Spanish fighting bull in order to bring in what is missing in Heck cattle. These new herds are called Taurus cattle [ 1,2,3]. Taurus cattle are bred in Germany, Hungary and Denmark. They are slenderer, larger and more long-legged than Heck cattle; also their skulls are longer and the horns face forwards. Good Taurus cattle are much more aurochs-like than usual Heck cattle, although strict selection is yet needed to achieve the Aurochs phenotype completely. 
In 2008, the Tauros Programme (or TaurOs Project) was formed. It is, besides the Taurus cattle, another project that aims to breed an aurochs effigy that is hardy and robust like other landraces to fit a life in wilderness. They work cattle from Southern and Eastern Europe and Highland cattle.
Apart from these projects, there are also a few other initiatives that aim to breed cattle that is propagated as aurochs proxies by their advocates.

The Tarpan/ western wild horse

Pleistocene wild horse skeleton (Image source: photobucket.com)















The Tarpan, Equus ferus ferus, (= the western subspecies of the wild horse) once ranged from Portugal to the Russian steppe and apparently displayed a number of different phenotypes (I will go into further details in a later post) [3]. Several breeds are propagated as surviving or bred-back Tarpans, which is not supported by the data. There are landraces resembling the Tarpan, or its respective phenotypes, though. The Konik is certainly the most popular of them (but only one of many), possibly because it is promoted as the result of an effigy-breeding program (which is actually not true) [5]. The Heck horse is a derivation of the Konik that on the other hand is the result of effigy-breeding, but not necessarily more Tarpan-like. Beside those, a number of other less-derived ponies exist that are at least as authentic but do not get the same attention. In a later post, I will go into greater detail which horse breeds resemble the Tarpan, and it turns out that the wild horses actually left their traces all over Europe.

The Quagga

The last known living Quagga which died in 1883,
displayed the zoologic museum of Amsterdam (Image source: horse-today.de















Effigy breeding focusing on the Quagga is fundamentally different from effigy-breeding with domestic animals because there are no surviving descendants of this animal. The Quagga, Equus quagga quagga, was a distinct subspecies of the plains zebra that was wiped out around 1900. It is famous for its secondary reduction of striping in its coat, what distinguishes it from all other zebra species and subspecies. The Quagga Project started in 1987 which aims so rebred the pelage characteristics by selective breeding for stripe reduction in a population of modern plains zebras [6,7]. After 25 years of breeding, the resulting animals do bear resemblance to the Quagga, although the real Quagga will remain extinct. I will go into much greater detail on the Quagga Project’s guidelines, arguments and recent results in a later post.

There also were some claims about the rebreeding of the Barbary Lion, Panthera leo leo. This northern subspecies of the lion is extinct in the wild and disappeared in its pure form because of hybridization with other subspecies. There are lions that are considered possible descendants of pure Barbary lions, and the Barbary Lion Project does (or did, I don't know if it is still running) research in order to determine the presence and degree of influence of the true Barbary lion in these living cats. If it really turns out that its genes are still present in a population of lions, breeding-back using genetic screening might restore a pure lineage of this subspecies [8]. 

As you can see, there are numerous breeding-back projects and results, but none of these has produced final results yet that clearly show all the desired features. Effigy-breeding isn’t easy or to be done quick: there is a precise picture the breed has to match with AND they have to be genetically diverse AND ecologically potent at the same time in order to survive as a wild animal in nature. The reasons why until now there is no "perfect" effigy-breed is either that some projects have not been running long enough yet, or that the breeding was not efficient enough in other cases. And, not to forget, the final step cannot be made by Man's artificial breeding but takes place when the animals are exposed to natural selection and become wild animals with surviving strategies and adaptions to their habitat.

Literature

[1] van Vuure, Cis: Retracing the Aurochs - History, Morphology and Ecology of an extinct wild Ox.
[2] Frisch, Walter: Der Auerochs – das europäische Rind. 2010.
[3] Bunzel-Drüke, Finck, Kämmer, Luick, Reisinger, Riecken, Riedl, Scharf & Zimball: „Wilde Weiden: Praxisleitfaden für Ganzjahresbeweidung in Naturschutz und Landschaftsentwicklung“. 2010
[5] Tadeusz Jezierski, Zbigniew Jaworski: Das Polnische Konik. 2008.
[6] Leonard, Jennifer; Rohland, Nadin; Glaberman, Scott; Fleischer, Robert; Caccone, Adalgisa; Hofreiter, Michael: A rapid loss of stripes: the evolutionary history of the extinct quagga. 2005.
[7] http://www.quaggaproject.org
[8] Yamaguchi, Nobuyuki: Barbary and Cape lions: Their Phylogenetic places and Conservation

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