[Taxacom] Polar bears as a subspecies or species

Jody Haynes jody at plantapalm.com
Thu Jan 22 06:14:56 CST 2009


We must keep in mind that the manner in which hybrids are treated 
taxonomically depends in large part on the species concept being employed by 
individual taxonomists. If you adhere to Mayer's Biological Species Concept, 
then Steve's and Ken's points below are certainly valid. But there are 
plenty of other species concepts that do not require complete reproductive 
isolation. Right now there are literally thousands of validly published and 
widely recognized species -- of both animals and plants -- that have the 
ability to successfully interbreed with other equally valid and recognized 
species and produce fertile offspring. Based on the argument below, would 
this, then, necessitate that all of these "species" should now be considered 
"subspecies?"

Jody

----- Original Message ----- 
From: "Kenneth Kinman" <kennethkinman at webtv.net>
To: <taxacom at mailman.nhm.ku.edu>
Sent: Wednesday, January 21, 2009 9:07 PM
Subject: [Taxacom] Polar bears as a subspecies or species


> Steve Manning wrote:
>     Which, when and if it happens, would emphatically justify combining
> grizzlies and polar bears into one species!  (Sorry, polar bears, you
> might have to get with the program!  But maybe a better ending than true
> extinction.) *****************************************************
> Hi Steve,
>      Well, maybe yes and maybe no.  It really depends on the
> "evolutionary health" of such half-breeds (are they intergrades or true
> hybrids).  If they freely interbreed with members of the parental
> species and produce fertile offspring, then that is evidence that they
> are merely intergrades between what are actually subspecies of a single
> species.  However, if there are fertility problems with such
> half-breeds, then that is evidence that speciation has most likely
> occurred and reproductive isolation is pretty firmly established.
>       The fact that we have confirmed two or more such half-breeds does
> not really answer this important question of the fertility of such
> individuals.  If they have fertility problems, it would only accelerate
> the extinction of the polar bear species.  If they don't, the polar bear
> "subspecies" would still most likely suffer a slow decline in an
> environment that reduces the advantages that they once had over their
> brown bear relatives.  Either way, pure-bred polar bears (species or
> subspecies) are in for very tough times as the ice continues to recede.
>          ---------Ken Kinman
>
>
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