Striping on neck suggests that extinct quagga is different species from Burchell's zebra

 (writing in progress) 

I come back to the question of the taxonomy of the plains zebra and the status of the extinct quagga: merely the nominate subspecies or a separate species in its own right?
 
In previous photo-emails I’ve pointed out that the mane of the extinct quagga is different from those of Equus quagga burchellii and E. q. chapmani, and that this incongruency supports the notion that the extinct quagga was distinct.
 
Perhaps I’ve not gone through the literature thoroughly enough, buy I don’t recall an examination of the neck striping along the lines which I present below.
 
My focus here is on the question: to what extent does shadow striping occur in burchellii, and is it the case that the neck striping of the extinct quagga is product of extreme encroachment of shadow striping in an anterior direction?
 
In fact, the neck striping of the extinct quagga does not seem to be the result of ‘exaggerated shadow striping’. Instead, the neck striping of the extinct quagga shows ‘reverse shadow striping’ in which the dark stripes develop relative pale centres. Has this ever been noticed before?
 
The gist of what I find here is that it is not the case that the neck striping of the extinct quagga is merely an ‘extension’ or ‘extrapolation’ of the trend seen as one moves southwards within the plains zebra. Instead, the neck striping of the extinct quagga, in keeping with the distinctiveness of its mane, is differently configured.
 
The following shows a specimen of ‘re-bred’ burchellii, in which there is clear encroachment of shadow striping on to the neck. This encroachment tends to occur mainly near the base of the mane, but there is one instance of it also on the part of the neck near the shoulder. If the extinct quagga were merely the nominate subspecies, then we would expect its neck striping to be even more extensively shadow-striped, to the extent of tending to occlude the pale stripes, not so?
 
https://quaggaproject.org/wp-content/uploads/2017/03/quagga-finch.jpg
 
The following specimen of ‘re-bred’ burchellii is ambivalent, because it shows both the encroachment of shadow striping on to the neck and the appearance of ‘pale centres’ in the dark stripes on the neck. Note that all specimens of ‘re-bred’ burchelli retain the long, mainly pale mane of the southern forms of plains zebra, including a prominent forelock.
 
https://i.pinimg.com/originals/d6/85/61/d68561d52d64d539fcb978741154f252.jpg
 
The following specimen of burchellii, presumably in Zululand, again shows shadow striping on the neck.
 
https://www.ioes.ucla.edu/wp-content/uploads/zebras.jpg
 
The following specimen of extinct quagga is fairly typical: the neck striping is not configured by means of exaggeration of the shadow striping shown above in burchellii. Instead, the dark stripes are exceptionally broad and have indications of development of ‘pale centres’, which can be thought of as a kind of ‘reverse shadow striping’. This represents a qualitative rather than quantitative difference from burchellii, in keeping with the differences in the mane, which is shorter and darker in the extinct quagga than in burchellii.
 
https://www.naturkundemuseum.berlin/sites/default/files/150209_quagga_01_c_carola-radke_mfn.jpg
 
The following specimen of the extinct quagga is ambivalent, showing what could be interpreted as shadow stripin as well as the ‘hollow centres’ to broad dark stripes. The relatively short mane is typical of the extinct quagga.
 
https://i.pinimg.com/736x/18/c4/10/18c410cc9a099c983d8a59656c148d67--extinct-donkey.jpg
 
The following shows the difference I’m describing.
 
https://www.ioes.ucla.edu/wp-content/uploads/Larison2_zebras2.jpg
 
I would have preferred the following to consist of photos rather than these rather poor paintings, but there is some value in it because it summarises the individual variation in neck striping in the extinct quagga. Please note the specimen in Mainz Mal., which seems to hint at an exaggeration of shadow striping.
 
http://img08.deviantart.net/1700/i/2015/269/b/d/the_quagga_s_coat_colour_variation_by_pachyornis-d9axzds.jpg
 
The following specimen of the extinct quagga shows the typical relative shortness of the mane, the lack of shadow striping on the neck, and the appearance of ‘hollow centres’ in the broad dark stripes on the neck, which I refer to as a kind of ‘reverse shadow striping’ rare in burchellii.
 
http://www.planet-mammiferes.org/Photos/Ongule/Equides/EquuQua5.jpg
 
The following specimen of the extinct quagga again shows ‘hollow centres’ rather than exaggerated shadow striping’.
 
https://i.pinimg.com/474x/df/1d/a9/df1da9b6fbd21b6e6240e408c897d8fd--zebroid-extinct-animals.jpg
 
Ditto.
 
https://i.pinimg.com/736x/07/19/bc/0719bc602b8a59cb77e30dc8d8df6ec6--modern-history-extinct.jpg
 
Ditto.
 
https://i.pinimg.com/736x/ed/23/be/ed23be6404cf361001b6a00d5acf989f--extinct-pegasus.jpg

In the following specimen of the extinct quagga, there is once again no indication that the striping of the neck has been formed by means of exaggeration of shadow striping.
 
https://upload.wikimedia.org/wikipedia/commons/7/73/Quagga_Naturhistorisches_Museum_Basel_27102013_3.jpg
 
In the following specimen of the extinct quagga, there is once again a hint of ‘reverse shadow striping’, not exaggeration of shadow striping.
 
http://www.mwnh.de/imag/mus085.jpg
 
The following specimen of the extinct quagga has exceptionally broad dark stripes on the neck. However, there is once again no indication that these dark stripes have been formed by means of coalescence of shadow stripes with main stripes. Instead, the only ‘shadows’ are ‘hollow centres’ to dark stripes, not so?
 
https://www.newdinosaurs.com/wp-content/uploads/2016/11/1123_quagga_ilvy.jpg
 
The following specimen of the extinct quagga shows similar patterns to those pointed out above.
 
https://farm8.static.flickr.com/7175/6770292233_72fdc51671_b.jpg
 
The following specimen of the extinct quagga shows the shortness and darkness of the mane particularly well.
 
https://ic.pics.livejournal.com/culpeo_fox/14913711/64359/64359_300.jpg
 
The following specimen of the extinct quagga shows an ambivalent pattern in the striping of the neck, but it is noteworthy that this ambivalence does not affect the mane, which is typical in its relative shortness and darkness.
 
https://equusasinus.files.wordpress.com/2015/08/quagga-london.gif

(writing in progress)

Posted on September 02, 2022 06:30 PM by milewski milewski

Comments

Posted by tonyrebelo almost 2 years ago

@tonyrebelo Many thanks for pointing out failed links. The above is a copy of a photo-email I sent, about 5.5 years ago, to Colin Groves, the authority on the taxonomy of zebras. Colin Groves has since died, and items have vanished from the Web. I will replace the failed links with working ones. However, the main point of interest is that Colin Groves acknowledged, in response, that be had never noticed these differences, and he expressed regret for having assumed that quagga was merely the southernmost subspecies of the plains zebra. Because Groves is well-known to be a 'splitter', the implication is that, had he spotted this difference himself, he would have kept quagga as a separate species. Regardless of taxonomic decisions, however, the difference of kind, as opposed to degree, may help to explain why it has proved so hard to 'rebreed' the extinct quagga from a ssp. of the plains zebra. The 'Rau quagga' standards are not actually sufficient for claiming any true, overall, reinstatement of the phenotype of the extinct form. The rebreeding projects have produced fascinating results, but it is a stretch to claim that they have 'rebred' anything. What has been produced is the palest form of plains zebra, as opposed to a semblance of the extinct quagga, not so?

Posted by milewski almost 2 years ago

I agree. But the issue is that an extinct species is now not recogized as extinct. it is merely "a few southern populations of Plains Zebra that have vanished".

Posted by tonyrebelo almost 2 years ago

@tonyrebelo Is your quote from an item in the literature?

Posted by milewski almost 2 years ago

No. impromptu.

Posted by tonyrebelo almost 2 years ago

Not quite on this topic, but have you seen what water does to zebra stripes: only the vertical stripes show. Why is that? (part of it is that the non-vertical stripes are on top and dont reflect, but why the hindquarters?)
https://www.inaturalist.org/observations/133454966
https://www.inaturalist.org/observations/133454958
Perhaps Zebra stripes are not for lions and hyenas but for crocodiles?

Posted by tonyrebelo almost 2 years ago

@tonyrebelo Well-spotted. This is an intriguing puzzle.

Posted by milewski almost 2 years ago

@tonyrebelo @jeremygilmore

Differences between extinct quagga and Equus quagga burchellii:

The following (http://l450v.alamy.com/450v/c797mt/zebra-in-hluhluwe-umfolozi-game-reserve-kwazulu-natal-south-africa-c797mt.jpg) shows an adolescent individual of Equus quagga burchellii, in Hluhluwe-IMfolozi reserve in Zululand.

It shows the maximum ‘darkness’ of this subspecies, in the sense that here we have the maximum breadth of the dark striping.

Note that, in this individual, a) the mane is, overall, as much dark-striped as pale-striped, and b) there is narrow dark-rimming on the front-of-ear.

However, the overall point is that, even when this subspecies expresses is ‘maximum darkness’, a) the pale striping on the mane remains whitish rather than fawn, and b) this applies also to the anterior part of the cheek.

Also note the length of the mane and forelock, which look about double the length seen in any museum specimen of the extinct quagga.

Some individuals of E. q. burchellii are darker than others. However, this darkness is not associated with any shortening of mane or forelock. Furthermore, the fawn tinge in the pale areas between the dark striping never seems to extend on to the cheeks, as it does in the extinct quagga.

All specimens of the extinct quagga, without exception, have the pale ‘ground-colour’ on the anterior part of the cheeks fawn, not whitish. Furthermore, I have yet to find a single individual of E. q. burchellii that has the ‘ground colour’ of the anterior part of the cheeks fawn, as opposed to whitish.

Although this individual of E. q. burchellii is particularly ‘dark’ for its subspecies, there is nothing ‘quagga-like’ about it, not so?

What this all seems to add up to:

One can select for darkness in burchellii, or one can select for stripelessness in burchellii. However, neither extrapolation is likely to approach the phenotype of the extinct quagga.

This is because no amount of darkening in burchellii ever seems a) to extend on to the ‘ground colour’ of the cheeks, b) to darken the pale striping on the mane, and c) to bring any shortening of mane and forelock.

By following the trend of stripelessness (as done in all the ‘re-breeding programmes), one is again frustrated. This is because no amount of extension of the shadow striping in the anterior direction (ultimately on to even the cheeks) seems to bring overall darkness. Equus quagga burchellii retains the paleness of its ‘ground colour’, even as its shadow striping is multiplied.

So, contrary to any previous tacit assumption, the darkness of the ‘ground colour’ in the extinct quagga is not the result of the accentuation and spreading of shadow striping.

The ‘re-breeding’ programmes have essentially tried to cover the animal in shadow striping, so extreme that it ‘fills in’ the pale areas of the pelage.

However, this has not worked, because the ‘ground colour’ - particularly on the head and mane - remains whitish, no matter how shadow-striped the individual may be, in burchellii.

Posted by milewski almost 2 years ago

@tonyrebelo @jakob @jwidness

When I Posted in explanation of the adaptive functions of zebra striping, you rightly pointed out that my hypothesis did not account for the incongruence between the colouration of the extinct quagga and that of other forms of the plains zebra.

This does remain a problem.

However, could part of the answer be 'the extinct quagga is actually a different species from the plains zebra'?

Posted by milewski almost 2 years ago

Equus quagga burchellii in Zululand, showing pale masseter area:
  
The following (https://thumb1.shutterstock.com/display_pic_with_logo/364990/364990,1311717883,34/stock-photo-zebras-at-hluhluwe-umfolozi-game-reserve-located-km-north-of-durban-is-the-oldest-proclaimed-81699373.jpg) of Equus quagga burchellii in Zululand (Hluhluwe-iMfolozi) shows the tendency to pale stripelessness on the masseter area, a tendency that occurs also in the intensely striped E. q. crawshayi. I have yet to see such a tendency expressed in any museum specimen of the extinct quagga. By the way, also note that the shadow striping extends as far to the anterior as the posterior-most part of the neck.

Posted by milewski almost 2 years ago

@tonyrebelo @paradoxornithidae

Photos showing difference in back-of-ear markings between Equus quagga crawshayi and Equus quagga burchellii:

http://safaritime.com/wp-content/uploads/2013/03/trophy-zebra-hunting.jpg

https://i.ytimg.com/vi/_WnsNZUOwlA/hqdefault.jpg

One if the undocumented aspects of the extinct quagga is the colouration in the posterior surface of the ear pinna.

Each species of Equus has its own pattern, or more precisely its own range of patterns among subspecies and individuals, in this part of the pelage.

In the plains zebra, the back-of-ear tends to be intensely marked with a complex pattern in the most intensely striped subspecies, vs nearly immaculate in other subspecies, particularly burchellii in the south, and borensis in the north.

There is a possibility that the pattern in the extinct quagga is different from that in any of the subspecies of the plains zebra. If so, this would support the notion that the extinct quagga was actually a separate species.

I have examined all the photos of museum specimens on the Web, and the only photo giving us a glimpse of the pattern in the extinct quagga refers to an infant in the South African museum in Cape Town (https://www.quaggaproject.org/quagga-project-founder/ and https://www.deviantart.com/viergacht/art/Quagga-foal-392906831). However, even in this case, the pattern is unclear.

The pattern could be documented by looking at the various museum specimens, but this would require either visiting the various museums, or requesting special photos of the ear pinnae from curators.

Posted by milewski almost 2 years ago

Jaques-Laurent Agasse (https://en.wikipedia.org/wiki/Jacques-Laurent_Agasse) was a competent painter with a particularly keenneye for equids.

Here is his depiction of a captive specimen of the extinct quagga, painted from life: https://commons.wikimedia.org/wiki/File:Agasse_Quagga.jpg

One can see from another depiction by Agasse (https://www.alamy.com/jacques-laurent-agasse-zebra-image367348337.html?imageid=EBC5D4C0-A4FF-4A38-9A81-A20D8DBE0F10&p=726102&pn=1&searchId=b09cd93958705b5d852dd2db560d38fc&searchtype=0) that he paid attention to detail on the posterior surface of the ear pinna.

It is obvious that Agasse erred by depicting the heads of quagga and mountain zebra as smaller than they really are. This is understandable in view of his the extremely 'refined' breeds of the domestic horse, which do indeed have heads smaller than those of any wild species in the genus Equus.

Agasse showed the back-of-ear of this individual of the extinct quagga as an irregular, medium-tone brown, with dark distally, and perhaps a spot of pale at the very tip.

Posted by milewski almost 2 years ago

scroll in https://prehistoric-fauna.com/Equus-quagga-quagga

The scientific art of Roman Uchytel is the best of its kind, available on the Web. However, his depiction of Equus quagga quagga is disappointing in several ways.

The brown parts of the pelage are far too pale.

The mane is slightly too long.

The back-of-ear is probably too pale.

The stated body mass is far too small (should be about 350 kg), and this error also applies to the human figure for scale.

The second individual, in the main scene, seems to dangle in space, the attempt at perspective having failed.

The background shows a more typical form of zebra. This is not necessarily incorrect in principle, because it is possibly that E. quagga quagga was sympatric with E. quagga burchellii in what is now Free State province of South Africa. However, what is shown in this background looks like Equus quagga boehmi, not E. q. burchellii.

Posted by milewski almost 2 years ago

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