The Geography of Tapirs

by Greg Mayer

Although far from the longest chapter in WEIT, I find the chapter on biogeography the single most persuasive one for showing why evolution is true.  I think Jerry finds it compelling as well. This might seem surprising since he’s a geneticist: one might think he would find some of the genetic evidence most compelling.  But I don’t think it is surprising, given that it was the biogeographic evidence, that, as the great zoogeographer P.J. Darlington put it, showed Darwin evolution.

Tapirs provide a nice example of the use of multiple lines of evidence in solving a biogeographic puzzle (a puzzle noted by an alert reader in the comments on my first tapir post).  Tapirs are usually thought of as South American (where they are most widespread and species rich), with one species in Malaya.

World distribution of tapirs (from Tapir Specialists Group)

World distribution of tapirs (from Tapir Specialist Group)

The first thing you might think needs explication is the disjunct distribution.  But before tackling this, a mis-impression must be corrected: although we tend to think of tapirs as typically South American, from a historical perspective, they are recent interlopers.  Along with many other animals we consider typically South American (jaguars, llamas, peccaries), they entered South America from the north about 3 million years ago when the Panamanian portal became the Panamanian isthmus during the Great American Interchange.

What, then about the disjunction: how did they get from Central  America to Malaya? They didn’t.  Tapirs are a northern group.  They and their relatives date back to the lower Eocene (ca. 50 mya).  The modern genus, Tapirus, dates back to the Oligocene (ca. 30 mya), and was found in Europe, Asia, and North America. They have gone extinct in Europe, most of Asia, and most of North America.  Tapirs thus have a relict distribution, being still found at two endpoints of their historical distribution. Geology, paleontology, and systematics thus combine to give a most satisfying account.

8 Comments

  1. Posted August 6, 2009 at 3:32 pm | Permalink

    Nothing makes sense in biology except in the light of…magic.

    That might not be right, though.

    Glen Davidson
    http://tinyurl.com/mxaa3p

  2. TheBlackCat
    Posted August 6, 2009 at 4:07 pm | Permalink

    What was the time frame of tapir extinction? Was it part of the general Holocene extinction event or something else? Did they survive into historical times?

    • TheBlackCat
      Posted August 6, 2009 at 4:18 pm | Permalink

      I mean “Did they survive into historical times outside their present range?”

      • Michael K Gray
        Posted August 11, 2009 at 5:20 am | Permalink

        No, they tapired off…

        • Jhon Evans
          Posted May 3, 2011 at 5:54 pm | Permalink

          It took 2 years, but someone got you joke.

  3. Hempenstein
    Posted August 7, 2009 at 9:46 pm | Permalink

    “extinct in Europe, most of Asia, and most of North America…..”

    Or maybe it was a punctuated Rapture. The extant tapirs better not look over their shoulders – they could be next!

    (Sorry, it just seemed that this nice post was worthy of a few more comments.)

  4. David Ewbank
    Posted September 10, 2009 at 11:13 am | Permalink

    tapirs survived until well into the holocene in china for instance in the yangtse valley until perhaps 1000 yrs BP. I’m sure I saw an Indian journal reference to tapirs in India c3000BP in early 90s but can’t trace it now – if anyboby knows this reference I’d be very glad to have have.
    Best Wishes

  5. whyevolutionistrue
    Posted September 10, 2009 at 11:23 am | Permalink

    Thanks for these tips on recent extinction– I too would appreciate references.

    GCM


Follow

Get every new post delivered to your Inbox.

Join 27,070 other followers

%d bloggers like this: