From: jespah@milton.u.washington.edu (Kathleen Hunt)
Newsgroups: rec.equestrian
Subject: more on equine species...
Date: 22 Jul 92 05:58:59 GMT
Article-I.D.: u.1992Jul22.055859.15352
Organization: University of Washington, Seattle

>From: pallas@cephalo.neusc.bcm.tmc.edu (Sarah Pallas)
>
>Equidae includes one genus (Equus) and seven different species.  These
>include Equus burchelli (Burchell's zebra), Equus grevyi (Grevy's 
>zebra), Equus caballus (the subject of this newsgroup), Equus asinus
>(domestic donkey), Equus hemionus (onagers/kiangs/wild asses), and
>Equus przewalskii (Przewalski's horse).  I could not find reference to 
>Equus zebra in my texts, but perhaps that is the 7th?
>
>Sarah Pallas
>(a zoologist, once upon a time)

Yes, _Equus zebra_ is the 7th.  The common name is Mountain Zebra.
Also _Equus hemionus_, the onager, is a separate species from the asses.  
All the asses/donkeys/burros, domestic and wild, are in _E. asinus_.  (The 
confusion comes from the onager sometimes being called a "wild ass" or
a "half ass" because if you say "onager" nobody knows what you're talking
about, and it looks more like an ass than like any of the other equines.
But really it's its own species.

Also I personally think the P-horse still belongs with _Equus caballus_
and hasn't attained species status yet (see below).

Several months ago I wrote an FAQ on horse evolution for the talk.origins
group -- if anyone is interested I'll e-mail a copy.  I'm reprinting the
bit about modern equines below, just to make this post longer than it
really needs to be.  :-)

Kathleen
who loves discussing micro-details of horse taxonomy
****************************************************************
From the talk.origins FAQ on horse evolution...

9.  MODERN EQUINES  (Recent)
The three-toed horses gradually died out, perhaps outcompeted by the 
phenomenally successful artiodactyls (or not).  Most of the one-toed horses 
in North America also died out, as the Ice Ages started.  (The causes of 
these extinctions are unknown.)  However, one-toed Equus was very successful. 
Until about 1 million years ago, there were Equus species  all over Africa, 
Asia, Europe, North America, and South America, in enormous migrating herds 
that must easily have equalled the great North American bison herds.  
   All the remaining horses of South and North America perished in the late 
Pleistocene extinctions (the ones that also wiped out the sabertooths & 
mammoths).  The only members of Equus -- and of the entire family Equidae 
-- that survived into historic times were:
Order Perissodactyla
[suborder Hippomorpha, as Sarah pointed out]
 Family Equidae
  Genus Equus
     _Equus burchelli_ -- the Plains zebra of Africa, including "Grant's 
         zebra", "Burchell's zebra", "Chapman's zebra", the half-striped 
        Quagga, and other subspecies.  
     _Equus zebra_ -- the Mountain zebra of South Africa. 
     _Equus grevyi_ -- Grevy's zebra, the most horse-like zebra.
     _Equus caballus_, the true horse, which once had several subspecies.
     _Equus hemionus_ -- the desert-adapted onagers of Asia & the Mideast.
     _Equus asinus_ -- the true asses [=donkeys=burros]  of northern Africa

  Of the three zebra species, only the Plains zebra still thrives, though 
the quagga went extinct in 1883 and other subspecies are dwindling.  The 
Mountain zebra is threatened and the Grevy's zebra is endangered.  
  The onagers and wild asses are endangered, though the domestic donkey is 
thriving.
  _E. caballus_, the true horse, is thought to have had 5 major 
subspecies in Europe and Asia.  Three were domesticated and have not been 
seen in a true wild state for thousands of years (they correspond roughly to 
the Arabian, the draft horse/pony, and the warmblood).  A fourth, the 
tarpan, survived in Poland till 1900 but then went extinct.  The fifth, the 
Przewalski's horse, went extinct in the wild and for decades survived only 
in zoos, barely surviving through a perilous bottleneck of less than 30 
animals.  One herd of Przewalski's horses has now been reintroduced to the 
wild --  the only truly wild, undomesticated _E. caballus_ in the world.  

(There is disagreement about whether or not the Przewalski's horse is a 
separate species.  It can fully interbreed with the domestic E. caballus,
to the distress of zookeepers, so by the standard definition of species
as a fertilely interbreeding population, the Przewalski's horse is a 
subspecies of E. caballus.  Some people call it a separate species, 
_E. przewalski_, because it has a different chromosome count.  I consider
it to be a subspecies that was on the brink of speciation.) 


**********************************************************	
More on those 5 subspecies of ancient times (from Deb Bennett's series
in Equus magazine a couple years back):
   E. c. libycus of southern Europe, adapted to hot climate & hard ground.  
Domesticated as the Arabian & Barb, & contributed to the Turk & Caspian pony.
   E. c. germanicus of northern Europe, adapted to boggy & cold conditions.  
Domesticated (sort of) as the tough Celtic ponies (Exmoor, etc.), and the 
Fjord, and contributed to all draft horses via medieval Great Horse, Black 
Horse, etc.   
   E. c. mosbachensis of central Europe, a "proto-warmblood"; essentially the 
middle of a heavy-bodied to light-bodied cline.  Domesticated as the typical 
solid-bodied, versatile riding horse.  (esp. Cleveland Bay, Friesian, 
Groningen).
   E. c. ferus, the tarpan, a tundra/steppe specialist of Asia.  Extinct, 
though it did contribute to a few breeds (Caspian pony & the Turk)
   E. c. przewalski, a closely related tundra/steppe specialist.  Survives in 
zoos and also contributed to the domestic Mongolian pony.  Bennett 
emphasizes that this subspecies did *not* give rise to most domestic Equus.
p.s. it's pronounced sheh-VAHL-skee, or so I've heard.....



-- 
"And this is a tiny radiotransmitter.  It transmits tiny radios through
 the air to this tiny radio receiver."
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