Friday, 13 July 2018

Transforming Leo into an aurochs

Some weeks ago, Claus Kropp published a photo of the young Sayaguesa bull Leo on facebook:
Sayaguesa bull Leo © Claus Kropp

Leo is from one of the best, if not the best, Sayaguesa herds that I have seen so far owned by Peter van Genejgen. Body shape, horn shape and skull shape are superb, the colour is good as well. The herd is slightly influenced by Alistana-Sanabresa, resulting in some reddish cows, giving the illusion of improved sexual dichromatism but bulls from the herd may happen to have a colour saddle (see here). For the European aurochs, there is only evidence for solidly black bulls. Leo has a colour saddle too, however, it still is a very beautiful bull and I think among the best Sayaguesa bulls I have seen. See his elongated head on this photo by Claus Kropp. When judging the body shape, keep in mind that it is still a young bull, it continue to gain weight while its skeleton will finish growing at the age of six years.

The beauty of the bull and the photo inspired me to do another photo manipulation. I took the photo and edited it using GIMP, trying to transform it into what I imagine a European aurochs bull to have looked like. Here is the result (as it is based on a photo by Claus Kropp, I asked if it was ok to present it here):
I changed nothing about the proportions, head size or head shape. I think they are pretty aurochs-like in the original already. I enhanced the morphology of the trunk: the hump had to be enlarged, and I gave it a more slender waist in order to achieve a more wild cattle-like morpology. Also I removed the colour saddle, as there is only evidence for black bulls in Europe and I am not convinced that there were European aurochs bulls with a colour saddle (see here). I removed the original horns and painted aurochs horns. I could have also reduced the length of the dewlap, but I was not sure. For comparison, here is an animated GIF composed of the original Sayaguesa bull and the "aurochs":

As you see, Leo is not that far removed from the goal. I am sure that many of his offspring will resemble the aurochs to a large extent by domestic cattle standards.

Thursday, 12 July 2018

Auerrind cattle are taking shape

Claus Kropp from the Auerrind project just published some new current photos of the first-generation Auerrind crosses at Kloster Lorsch, Germany, on facebook. It looks like they are becoming little bulls and cows now, not calves anymore, and start to take their final shape and colouration. All of them are copyright by Claus Kropp, so please do not replicate without permission. 

Maremmana x Watussi 
© Claus Kropp
© Claus Kropp
In the bull, it looks like Maremmana has absorbed almost all of the zebuine traits (at least those not present in Podolian cattle anyway, which are already influenced by zebus), only a slight hint of the zebuine hump seems to have remained. Watussi contributed dominant alleles for the expression of red pigment in the coat. So in the end, the bull might look like a red Maremmana bull with large horns, which would be a pretty interesting sight. A (Maremmana x Watussi) x Sayaguesa might be a combination worth considering, it might end up similar as Sayaguesa x Watussi but with less zebuine influence and a better winter coat. 

Sayaguesa x Chianina 
© Claus Kropp
© Claus Kropp
Both the Auerrind project and the Lippeaue have produced a couple of Sayaguesa x Chianina in sum by now, and it seems that about 50% of the bulls of this combination have a wildtype colouration and 50% have a diluted coat colour. I do not know why. However, it does not matter at all what the phenotype of these F1 look like since both the phenotypically wildtype and the colour-diluted individuals will have both alleles and pass on one of these with a 50/50 probability. So I think that this bull should be used for further breeding in any case. Its offspring will have the potential for a correct, un-diluted wildtype colour, even in a homozygous state (although it not the statistically most likely case). 

Sayaguesa x Hungarian Grey 
This cow seems to develop a slender body, the colour is diluted and the horns will probably end up Steppe cattle-like. Together with a bull of the same combination, a Sayaguesa x Chianina or a pure Sayaguesa it might produce interesting results. 

It also seems that they are giving the combination Chianina x Watussi a try again, which I am very much looking forward to: 
© Claus Kropp
They also published a promo video on a new youtube channel: 


I have to say it is very exciting to watch the Auerrind project progress. They have very, very good founding individuals and are trying interesting and promising combinations. I think they have the potential to produce very aurochs-like individuals in perhaps the second and very likely the third generation already. 

Wednesday, 11 July 2018

B.p. namadicus: bone material + new artworks

I already did a couple of posts on the Indian aurochs, Bos primigenius namadicus, the most comprehensive and up-to-date being this one. At the time of writing that post, the only picture of original material of this enigmatic subspecies I knew was a drawing of one skull. Thanks to a Carnivora Forum member I finally came across photo material of a few specimen. The two upper photos show bulls for certain, I am not sure about the last one.

The skull material



The crania show some very interesting morphological differences to the European subspecies, B. p. primigenius. First of all, the skulls are definitely narrower than European skulls (the upper one might still be within the variation range, though) and most zebus tend to have a very slender face as well. The horns of the known specimen are, as given in the literature, wide-ranging and considerably longer in proportion than the average for European skulls (which had, though, regional and chronological variation).  Considering that many zebuine or zebuine-influenced breeds tend to have large to very large horns, this might be a basal trait – although the huge horns of, for example, Watussi and similar breeds have certainly been enhanced by domestication.
There is also a more precise drawing of the Lydekker skull available on the web, which also shows it in lateral view. At least this skull seems to have the same 60° horn orientation as in the average European aurochs.


New Indian aurochs art

Seeing these photos of original bone material of the Indian aurochs has inspired me to do some new life illustration of this interesting subclade. As explained in the post linked above, there are a few traits that can be said with certainty, some that can be inferred by parsimony and some traits displayed by zebuine cattle might actually be wildtype traits of the Indian aurochs.

Directly proven traits:
- smaller body size, perhaps between 150-160cm for bulls
- proportionally longer, wide-ranging horns

Traits inferred by parsimony:
- a more slanted pelvis than in taurine cattle
- basic aurochs and wild cattle morphology (long legs, athletic body)
- E+ base colour

Zebuine traits that might in fact be wildtype traits:
- longer dewlap than in the European aurochs (functional purpose: thermoregulation)
- zebuine colour modifiers

Putting everything together, here is the result:

The head and horn shape was drawn to match the skull material. I tried to give the face a kind of zebuine appearance. The body shape is the classic aurochs body shape (I do not assume any differences in proportions, hump size or other morphological traits as long there is evidence for). As for the colour, here is were intuition comes into play. Many zebus show white areas between the forelegs, on the dewlap and also the underbelly, which is said to be caused by a “zebuine tipping gene” (it is not specified whether it is an extra locus or just an allele) and also displayed by other bovine species. I like to illustrate my namadicus with this trait. Also, zebus tend to have another form of colour saddle, different from taurine cattle. It is not a true saddle that covers the upper middle part of the torso, but the sides and often merges fluently into the “zebu tipping area”. Many zebuine bulls show this trait, and it might just be a consequence of reduced sexual dimorphism as in taurine bulls, but for this drawing I assumed it to be a wildtype trait. It is pure speculation, but intuitively I think it is not an improbable colouration for a tropical bovine, which tend to be more colourful than boreal ones.
I also did not give it any curly forelocks. Forelocks are well-proven for the European subspecies and the wide majority of taurine bulls and also cows have them, yet no zebuine cattle show curly forelocks. Tropical bovines tend to have skin flaps and long dewlaps for display, while those in temperate climates tend to have hairy ornamentation for thermoregulatory reasons, thus I think it is plausible that Indian aurochs did not posses forelocks but an elongated dewlap instead. In previous posts I ruled out that the zebuine hump has any function, and therefore did not assume its presence for Indian aurochs. However, a Carnivora Forum member pointed out it might have had a display function in the wildtype, just as the enlarged processus spinosi have in Gaur and Banteng. This is very speculative, however, and probably only prehistoric art could provide a clue.

Being motivated by my new Indian aurochs bull portrait, I could not hesitate to do a table of bulls of all three aurochs subspecies along with their domestic descendants.

As there is only evidence for black aurochs bulls in Europe, I gave the primigenius bull a solid black back. However, for the African aurochs, there is evidence from at least two artworks that at least some bulls of this subspecies had a colour saddle (see here). So the colouration of the African bull is not as speculative as that of the Indian bull. It might as well be possible that all three geographical variants had a solid black colour like the European one. As there are no morphological differences between the African and European aurochs noted in the literature, the African and the European aurochs are actually the same drawing, only the colouration is different. The subspecies that sticks out is the Indian one, which is not surprising considering that the lineages of taurine cattle and zebuine cattle, and thus B.p. primigenius and B.p. namadicus, separated 1,7-2 million years ago[1], which is considerably longer than between Przewalski’s and domestic horses, for example. Here is a close-up for the Indian aurochs alone:
I think the drawing does look plausible for the wildtype of a bull like this one down below.


Something interesting that I noticed is that the size difference between all five bovines is not that huge, especially not between the wildtypes and their domestic derivatives. I drew them to the same scale. For the European aurochs, I chose a size of 170cm at the withers, for the African 160cm and for the Indian aurochs 150cm (which is, by the way, the lower size limit for European mainland bulls). The taurine bull has a height of 140cm, the zebu about 135cm. But the size difference does not appear that large. I think the reason for that is that withers height is not the most reliable measure for this comparison, as it is dependent on the size of the hump i.e. the length of the processus spinosi, actually. In very derived taurine bulls and most zebu the height of the spine does not surpass that of the shoulder blade, thus a domestic bull with a withers height of 150cm would have a larger body than an aurochs of the same withers height, especially considering that they are more elongated in build. So what is actually better comparable is the height of the shoulder blade. The question is, how much higher is the actual height of the shoulder blade of aurochs compared to cattle? Is it due to scaling or is the size difference between aurochs and cattle not that large in the end? The best way to evaluate that would be to compare a skeleton of a grown aurochs bull to that of a domestic bull in real next to each other. But considering that heavy bulls of domestic breeds can easily exceed 1000kg living weight while estimations for aurochs bulls are about 700kg  (by Cis van Vuure, I have reasons to believe they might have been actually 100-200kg heavier, but more on that in an upcoming post) it might not be that improbable. Surely, some aurochs individuals truly were huge by cattle standards as there are skulls of European aurochs with a length of more than 90cm.

In any way, I did an animated GIF of a the European aurochs and the taurine bull at the same withers height – it is obvious that the taurine bull has a way larger body due to the low processus spinosi and the elongated trunk. Even the head would have the same size. A taurine bull with a shoulder height of 170cm would have a weight of about 1700-1800kg, which is twice as much as what is estimated for an aurochs bull of that size.
“Breeding-back” with zebus, once again

In all my previous posts on the Indian aurochs, I introduced the idea of “breeding-back” with zebus. India is full of zebu landraces that are not well-known elsewhere but would be suitable for such a project as they have a slender, squarely-built body with long legs and long snouts. These include Kenkatha, Malvi, Ponwar, Haryana, Khilari or the large-horned Gudjerat. Such indigeneous zebus could be crossed with Watussi for the horn size and curvature and miniature zebus for the aurochs-like colour and dichromatism. Both Watussi and miniature zebu have taurine introgression, but as we know from “breeding-back” with taurine cattle, it is impossible to keep the taurus and indicus lineage 100% separated and it is the contributed traits that count, not pedigree. While the morphology and external appearance of the European aurochs is well-known and breeding with its descendants can approach most of its traits rather well, the life appearance of the Indian subspecies is far less well-known and zebus seem to be a bit more removed from their ancestor than taurine cattle. At least, there are no truly overall primitive zebuine breeds. However, breeding with the zebuine cattle listed above can produce a population that resembles namadicus in horn shape and size, proportions, skull shape and probably also colour. Most interesting would be to release them in a reserve and let them live for themselves for a number of generations. Heck cattle in Oostvaardersplassen underwent morphological changes after a mere 30 years of natural reproduction (see here, here or here) and it is likely that these zebu would experience something similar. These changes would be functional and evolutionary advantageous as they are the result of natural selection. Therefore, it would be interesting what happens to the shoulder- and neck region of the cattle. In Oostvaardersplassen, Heck cattle developed a tendency to have a stronger shoulder region including the typical hump of wild bovines with elongated shoulder spines that support larger neck- and shoulder muscles which are needed during combat. In zebuine bulls, the neck muscles seem somewhat weaker which might be a consequence of the fleshy zebuine hump which is caused by a hypertrophied M. rhomboideus. Thus, a bull with a zebuine hump might be in disadvantage compared to such with a wild cattle-like shoulder morphology. If, after a couple of generations, the zebuine hump would indeed disappear and they would develop a wild cattle-like hump like Heck cattle at OVP, it would be a strong hint that the fleshy zebuine hump is an artefact of domestication and was not present in namadicus as it is not functional. If, however, zebus do indeed use it for display, head-to-head combat might play a lesser role in their social life than in taurine cattle, and it might remain. This can only be demonstrated by executing such a zebu dedomestication experiment.

Other posts on the Indian aurochs: 

Literature

1 Hiendleder, Lewalski, Janke: Complete mitochondrial genomes of Bos taurus and Bos indicus provide new insights into intraspecies variation, taxonomy and domestication.2008.

Further, for the description of namadicus and africanus in the Literature:
Van Vuure: Retracing the aurochs: history, morphology and ecology of an extinct wild ox. 2005.



Thursday, 21 June 2018

New photo of some Tauros bulls

Geer vanne Smeed published a new photo of four Tauros bulls at Kempen~Broek on columbusmagazine.nl
Tauros bulls in Kempen~Broek © Geer vanne Smeed
Anyone can guess what kind of breeds or crossbreeds these bulls are and it is probably impossible to find out with the information given in the web, but I speculate that the lying bull at the right might be a pure Maronesa, the bull left to it a Maronesa crossbreed, the bull right in the back a Maremmana crossbreed and no idea on the last one. 

EDIT: Geer vanne Smeed told me that according to his opinion the crossbred bulls might be Limia x Maremmana, Maremmana x Maronesa and Maronesa x Limia as those were the breeds present in the herd during the last years 

As to the looks of the bulls, the colour is flawless in all individuals. The body shape of the bulls in the foreground cannot be determined as they are lying on the ground, but all of them seem to have a hump and are not that bulky. They might not be quite as large and long-legged as average Taurus bulls, but it is clear from the photos that they are more aurochs-like than classic Heck bulls (such as this one in Vielank, for comparison). As the Tauros Programme and the Auerrind project are cooperating now, future generations might obtain the genes for really large-sized and large-horned animals thanks to Chianina and Watussi-influence. 
I especially love the head and horns of the putative Maronesa bull in the front. The horn curvature is identical to some European aurochs skulls (mind that those only show the horn cores, so that the horn sheath would make them longer and more pronounced in life, i.e. the horns of the bulls are still a little shorter and less curved than in an aurochs), and the snout is not as shortened as usual in Maronesa and still longer than in many Heck bulls. 

Wednesday, 20 June 2018

Auerrind update

It has been long ago that I published my last post, and a lot happened. Especially the Auerrind project had some important achievements in the meantime: 

Cooperation between the Auerrind project and the Stichting Taurus 

Claus Kropp announced in April 2018 that the Auerrind project and the Stichting Taurus, which is responsible for the Tauros programme, are going to cooperate. The cooperation will include: 
- Exchange of suitable crossbred individuals 
- Sharing of research results 
- Conservation of the founding breeds 

Especially the exchange of suitable crossbred individuals sounds promising and it could result in a mutual benefit for both projects. The Tauros Project could finally get genes for truly large body size or horn size by acquiring Chianina or Watussi influenced Auerrind individuals, and the Auerrind project could get genes for decently inwards-facing horns via Maronesa-influenced Tauros individuals. 
I see the exchange of individuals as a middle-term perspective, as both projects are in a comparably early phase of crossbreeding yet. 

Incorporation of the Auerrind project into Rewilding Europe 

In May 2018 it was announced that the Auerrind project is going to join the network of Rewilding Europe. This will probably greatly help the project to acquire more suitable areas for their herds and increase volume of the project. 

New photos of the first-generation offspring 


Sayaguesa x Chianina calves (Photo © G. Pfirsching, published on auerrind.wordpress.com)
The herd in Lorsch has three healthy Sayaguesa x Chianina calves, two cows and one male. I think this is magnificent; as both the Chianina and Sayaguesa of the Auerrind project are of excellent physique and have good horn shapes, true F2 of this combination have the potential to result in very large, well-shaped and correctly coloured animals with good (albeit not very large) horns. 
Sayaguesa x Maremmana bull calf © auerrind.wordpress.com
The Sayaguesa x Maremmana bull calf seems to develop a wildtype colouration, it will be interesting to see how its horns are going to get. 


Maremmana x Watussi cow published by © Claus Kropp on Facebook
The young Maremmana x Watussi cow has a perfect, shiny reddish aurochs colouration. The horns will probably end up in an upright position because of the breed combination, but that can be fixed in future generations. It is interesting how the combination of the allele(s) for the wildtype distribution of the black pigment, contributed by Maremmana, and those for the production of red pigment, contributed from Watussi, resulted in a perfect wildtype colour phenotype. 
Sayaguesa x Hungarian Grey cow published by © Claus Kropp on Facebook
The young Sayaguesa x Hungarian Grey cow is now old enough to show its final colouration and also how its horns will get. All in all it resembles me of some Tauros and Taurus cows, which is what I predicted because of the breed combination. It is interesting that the alleles for red pigmentation of Sayaguesa are seemingly less dominant than those of Watussi, as also the grown Sayaguesa x Chianina cows show a reduced red pigmentation. 
Sayaguesa x Watussi next to a young Cachena bull © Claus Kropp
The Sayaguesa x Watussi bull now shows its final coloration and it is perfectly aurochs-like. Body and head shape seem to reveal the Watussi influence but it has no fleshy hump and the dewlap is not that long. It will be very interesting to see it fully grown, especially because of the horns. Actually, this is the offspring that I was most excited on because I have the suspicion that this bull bred to the three Sayaguesa again might result, with a bit of luck, in one of the best breeding-back individuals born yet in terms of overall impression. This is for the simple fact that the Sayaguesa of the project are very, very good and a considerable increase of horn volume would turn them into animals pretty close to the goal. Thus I really hope the project gives 75% Sayaguesa 25% Watussi a try. 

Tuesday, 27 March 2018

New photos of Tauros cattle from 2017 and 2018

As the primary webpresence of the Tauros Programme is not very comprehensive considering their multiple herds and crossbreeding results, one has to pick together information and picture material from all possible kinds of other sources. In this case, someone else did it for me and I want to present some of the photos here. 
The identity (that is, ancestry and breed combination) of 99% of the individuals is not evaluable for non-members of the Tauros Programme, and I have become quite tired of trying to make guesses based on the animals' look what kind of combination they might be, because having experiences in looking at crossbreeds of aurochs-like cattle will tell you it is nearly impossible. However, in some cases where it is a bit less unclear I will share my thoughts/suspicions with you, but at the disclaimer that it could always be something completely different. 

Maashorst
©Bert van Zijderveld
This the Maashorst bull. Breed combination is unknown to the public, but it might be another Maremmana x Pajuna - at least its looks are completely intermediary between both breeds. The photo reveals that he cannot be very large, perhaps the size of a Heck bull (and thus about 140cm at the shoulders or so). 
© Marcel Bakker
© Marcel Bakker
The above photo is the first photo I have ever seen that shows wisent and aurochs-like cattle next to each other. It is good to see both species side by side once again. Once fence will be removed, it will be very interesting how the two species will interact behaviourally, ecologically and reproductively. 
© Marcel Bakker
Photos like these worry me, on the other hand. In most grazing projects the cattle are fenced of for reasons of conservation and commonsense, but here cattle and visitors obviously can approach each other closely and it is only a matter of time until that goes wrong. One incident might be enough to mark the end of the herd. 

Herpeduin 
© Ingrid van Thiel
The Herpeduin bull in profile view. He has really nice looks, although the horns could face more inwards. I like its elongated snout and the shoulder hump, the colour is beautiful. I think he is likely that it is half Maremmana, no clue on the other half. 
© Ingrid van Thiel
The long snout of this cow is remarkable. No idea whether it is a pure cow or a crossbreed. 
© Ingrid van Thiel
Most likely a cross cow. 

Keent 

Photos by Peter Mulder on FlickR
The photo gallery shows a lot of photos of various animals from Keent, some are pure others are young crossbreeds. Most of the offspring is from Manolo Uno, the Maremmana x Pajuna bull, but the exact combination of the individuals is not determinable for me. 

Ziva voda Modra 
From link
© Michael Köpping
This is a new herd in the Czech Republik, built of three animals born in Milovice. 


All in all, I like most of the individuals. Many of them are comparably slender, some of them have elongated snouts and others have a horn volume that is at least not small. Most of them have an authentic colour with a tendency towards a satisfying sexual dimorphism. They do resemble Taurus cattle, which is not surprising that both projects use similar or the same breed (Sayaguesa) and both strains resemble their common ancestor, the aurochs. However, what I still miss is a breed that reliably adds large size and long legs, as most of the cross results so far as much as many of the founding breeds/individuals, lack large body size and many of the bulls could be more long-legged. Also, they might need a boost in horn volume. Although the horns of the individuals of the Czech herds are comparably impressive, they are still smaller than the usual spectrum found in the aurochs, especially considering that we are comparing horn sheaths of the living animal with the fossil and subfossil horn cores of aurochs skulls. Most of the crossbred individuals lack the inwards curve of their horns, the horn tips regularly face outwards. It is not easy to fixate inwards-curving horns in a "breeding-back" herd as this trait is very rare among primitive breeds. This is a universal problem in "breeding-back" herds. The Taurus cattle herd in the Lippeaue has a number of individuals that are good in this respect because it is strongly influenced by a Sayaguesa cow with accurately inwards-curving horns (named Dona-Urraca) and many of the founding Heck cattle and Chianina were not entirely contraproductive in this respect as well. So the Tauros project needs a breed or at least good individuals contributing this trait. They already use Maronesa, which is the breed with the most pronounced inwards-curve in my opinion, which is an advantage. So in order to increase the frequency of aurochs-like inwards-curving horns it might be wise to increase the influence of Maronesa on the herds. They might then need the influence of a truly large and long-legged breed to compensate. The Tauros Programme revealed that they consider using Maltese cattle, a breed where the more primitive herds are truly remarkable regarding body conformation, proportions and skull shape (I hope they are comparable to Chianina in size). They would probably be very beneficial for all of the Tauros herds, but it is not clear whether they have made a serious effort yet to get their hands on individuals or semen from this breed. 

However, I think there is no need to hurry or to draw premature conclusions yet. As far as I can tell, the Tauros Programme is still in the "building up quantity" phase, that is, creating herds and breeding sites in various countries and waiting for them to grow. Once the desired quantity level is reached, they can start to focus on quality. Deficiencies that might become evident, like a lack of size or horn volume/curvature, can be fixed in that stage by more stringent selection or the inclusion/increase of the use of certain breeds that add these elements that are missing. 

Friday, 23 March 2018

Two more calves for the Auerrindprojekt

Two more calves for the Auerrind project have been born. They were born by two Chianina cows (one of them is La Nova with a withers height of 165cm) and the father is Leo, one of the two Sayaguesa bulls of the project. So the calves are Sayaguesa x Chianina, a combination that has already produced a number of interesting animals in the Lippeaue (see here or here). One calf is male and the other one female. Therefore, theoretically, F2 of this interesting and promising combination are possible in about three years. The genetic basis would be comparably narrow as it would be the result of the mating of halfblood-siblings, but as the parental generation is composed of two non-related breeds, the genetic basis should be or at least might be broader than between two randomly selected average Frisians or Fleckvieh. And diversity can still be added in later generations. 

A comprehensive report on the current state of the breeding herds of the project is about to come according to Claus Kropp. 

Friday, 23 February 2018

A feral ancestry for the Przewalski's horse

Sometimes timing is funny. In November 2017 I wrote a post defending the Przewalski's horse's status as a wild animal. A new study by Orlando et al. has challenged the status of the Przewalski's horse as the last living genuine wild horse.
The earliest archaeological evidence of horse husbandry is from the Botai culture of Kazakstan from 5.500 years ago. It has been assumed previously that these Botai horses belong to the earliest strain of domestic horses of the caballine lineage. Surprisingly, the authors found only about 2,7% Botai-related ancestry for all domestic horses from 4.000 years ago, while the authors claim the Botai horses turned out to be the ancestral stock of the modern Przewalski's horses population. I have not read the paper yet because it is behind a paywall, thus I cannot see what led the authors to the conclusion that all modern Przewalski's horses descend from the Botai population and not just that the Botai population was part of the przewalskii clade. But let us assume the former is the case for now.
The authors thus write that Przewalski's horses are feral descendants of these early domestic horses, and not true wild horses. I have problems with the latter part of the conclusion. First of all, the horses of the Botai culture must have been in a very early state of domestication, and not for a long time. After escaping human husbandry, those early domestic horses have been exposed to natural selection for four millennia again. Any changes that might have occurred in the early state of domestication must have adapted to the requirements of living as a wild animal again. Thus, I don't regard the short (in evolutionary terms) episode of domestication as substantial enough to categorize the Przewalski's horse as feral instead of a wild animal. In fact, ever since its discovery, the Przewalski's horse has been used as a model for a wild equine and numerous differences in physiology, development and behaviour have been noted between the Przewalski's horse and domestic caballine horses as much as feral caballine horses. Przewalski's horses are way less tamable and more aggressive than domestic caballine horses, and genomic studies have shown that numerous genes for physiological aspects have been altered through human utilization while that is not the case in the Przewalki's horse[1]. The recent study by Orlando et al., or to be precise the short period of early domestication, does not alter this fact. The situation is not comparable to mustangs and other feral caballine populations at al.
Thus I do not regard the Przewalski's horse as any less wild as before. One could use it as an example for a "post-domestic wildtype", a term I tried to introduce in my posts on dedomestication as opposed to "pre-domestic", a term that is already used. However, I am rather confident that the majority of authors will begin to list the Przewalski's horse as a feral horse now, as the 19th century conception of  nature and evolution as something static and humans as an irreversible altering factor is still prevalent in a lot of experts heads. Unfortunately, in my opinion.

Interestingly, the authors found the alleles for the Leopard spotted colour present in the Botai horses. This colour variant has already been found in Pleistocene wild horses (see earlier studies of Orlando et al.).

Literature

Orlando et al. 2018: Ancient genomes revisit the ancestry of domestic and Przewalski's horses.


[1] Schubert et al.: Prehistoric genomes reveal the genetic foundation and costs of horse domestication. 2014.

Monday, 19 February 2018

Biological basics pt. III: Subspecies

In Biological basics III: The species concept – a complicated issue, I gave a little overview over how a species is usually defined and what a species actually is. Today’s post is going to look at subspecies. The understanding of the concept of a subspecies is necessary for some aspects of “breeding-back”, such as the issue of using zebus in aurochs projects and, more essentially, the Quagga project. Subspecies are sometimes called a cop-out, nit-picking or something for bored taxonomists, and I am going to outline why this critique is not fact-based.

Subspecies – something for bored taxonomists?

The short and definite answer to this is No. As Charles Darwin already noticed absolutely correctly and perfectly subsumed, subspecies are incipient species and the line between varieties, subspecies and species is gradual. As he noted in his opus magnum, On the origin of species, species are basically “strongly marked varieties”, and subspecies are a state in between. And as the previous post on hybridization has shown, even the line between species is blurred because many closely related species are able to hybridize with limited or unlimited fertility. In many cases there is uncertainty on whether two or more species should be regarded as subspecies of one species, or whether two or more subspecies should be elevated to species level. However, for this section on the concept of a subspecies and what justifies it from a biological point of view, I will try to focus on examples for which there is a consensus.

Subspecies are in a beginning state of cladogenesis, a speciation mode that I already explained in part I. It is the case when populations diverge and become more or less isolated, and the allelic frequencies start to change due to genetic drift, mutation and selection. These changes not only concern neutral genetic variations but all biological aspects: morphology, behaviour, ecology. This is especially enforced by the fact that the different populations often experience different selective pressure due to a different environment. This is particularly true in species with a large geographical range, especially when it is disjunct (isolation). Thus, the different populations become regionally adapted additionally to coincidental differences caused by genetic drift. In some cases, the differences between populations or group of populations assigned to different subspecies may concern only single traits like colour variants, but in some cases the differences are well-marked and concern a number of biological aspects. I am going to go over some examples.

The classification of subspecies experiences the typical taxonomical problems of subjectivity and tradition, and therefore is not always consistent. In some cases two subspecies might be as distinct as a pair of species, and vice versa. There is no clear line as taxonomy is an artificial system that aims to classify the complex reality of organismic relationships.

One example clear example of a species that is divided into two subspecies is the American Bison Bison bison. This species is divided into a northern subspecies, the wood bison B. b. athabascae, and a southern one, the plains bison B. b. bison. Both differ ecologically and morphologically; wood bison dwell boreal forest regions and are adapted to lower temperatures, while plains bison live in more open regions and are less (but still very) cold-adapted. Wood bison are larger, have a darker pelage and less hair on the forelegs and beard. Also, the hump is shaped differently.

The African buffalo, Syncerus caffer, is divided into five subspecies. The nominate form, Syncerus caffer caffer, has the southernmost range, is the largest subspecies and very dark in colour. S. c. brachyceros, is smaller, weights only half as much and is lighter in colour. The smallest subspecies, the forest buffalo S. c. nanus, differs considerably ecologically and morphologically. It inhabits the swampy forest areas of Central and West Africa instead of dry grasslands, it is very small (withers height less than 120cm), a bright orangish-red colour instead of greyish to black-brown, small horns and brushy hair on the ears. Some authors have suggesting listing it as a separate species, and since the Caucasian wisent which differs from the nominate form less drastically is considered a separate species now (Bison caucasicus), I definitely list the forest buffalo as a separate species, Syncerus nanus. This is a good example that shows that taxonomy is often subjective and not consistent.

A prime example for a species with a large geographical range and many different subspecies that are morphologically and ecologically distinct is the wolf, Canis lupus. Its large, Holarctic distribution includes more than a dozen subspecies that all differ in colour and morphology, body size, environmental adaptions, and to a certain degree behaviour. For example, large subspecies such as the nominate form C. l. lupus weight twice as much as smaller subspecies such as the Arabian wolf  C. l. arabis or pale-footed wolf and have a stronger and more robust build; smaller wolves live in smaller packs and are less macropredatory. Wolf subspecies can be adapted to totally different climates; the Arabian wolf for example inhabits the hot arid climate of the Arabian peninsular, while the polar wolf C. l. artcos obviously is adapted to arctic conditions. Wolf subspecies also differ in colour nuances.
Another predatory species that has a large range that includes many different subspecies with different morphological characteristics is the lion, Panthera leo. Lion subspecies can be adapted to different ecologic environments and may differ in body size and mane for example, and the diversity in the species becomes even greater if you include Pleistocene forms.

There are many other examples in all possible vertebrate groups that show that subspecies are clear evolutionary lines with distinct morphological, ecological or ethological traits. In some cases the situation is more clear and distinct as in others, but subspecies are definitely not something for “bored taxonomists”. It makes sense to differentiate subspecies not only from a taxonomical standpoint, it also appreciates the evolutionary, ecological, morphological and ethological situation within a species. Therefore, subspecies are a very useful and justified concept, which is followed by all zoologists (quite frankly, I have never heard of any zoologist deeming the subspecies concept as not useful and not using it).

A special case of evolutionary variation within a species is the so-called cline. In this case there is not a clear differentiation into several lineages, but variation along a geographic or ecologic gradient. This is comparable to the concept of a ring species that has been explained in the previous post. The quagga, Equus quagga quagga, has been suggested by some to represent the end of a cline rather than a distinct subspecies, although I think this should be backed up by empirical evidence (see this post on the quagga).