[Taxacom] Polar bears as a subspecies or species

John Grehan jgrehan at sciencebuff.org
Thu Jan 22 12:35:32 CST 2009


Even reproductive information may not introduce any greater clarity. I
recall (hopefully correctly) the case of a frog species in the eastern
us where adjacent populations can successfully interbreed, but the frogs
at each extreme of the range cannot.

John Grehan

> -----Original Message-----
> From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-
> bounces at mailman.nhm.ku.edu] On Behalf Of John Noyes
> Sent: Thursday, January 22, 2009 1:15 PM
> To: Jody Haynes; Taxacom
> Subject: Re: [Taxacom] Polar bears as a subspecies or species
> 
> Hi Jody,
> 
> The answer to that is not easy and straightforward, but personally I
> would say yes, they are the same species. However, mammal and bird
> taxonomists have a different approach to most insect taxonomists (I am
> an insect taxonomist) for many reasons. In many cases, the decision
has
> to be made using a pragmatic approach (legal or otherwise) to accept
> them or not as valid species. In the vast majority of cases,
taxonomists
> do not have sufficient data available using reproductive isolation as
a
> criterion and have to rely on morphological, molecular or biological
> discontinuity.
> 
> John
> 
> 
> Department of Entomology
> Natural History Museum
> Cromwell Road
> South Kensington
> London SW7 5BD
> UK
> jsn at nhm.ac.uk
> Tel.: +44 (0) 207 942 5594
> Fax.: +44 (0) 207 942 5229
> 
> Universal Chalcidoidea Database (everything you wanted to know about
> chalcidoids and more):
> http://www.nhm.ac.uk/research-curation/projects/chalcidoids/
> or
> http://www.nhm.ac.uk/entomology/chalcidoids
> 
> Interactive catalogue and biological database of World Chalcidoidea on
> CD:
> Contact the publisher: DickyS._Yu at telus.net, or Dicky S. Yu, P.O.Box
> 48205, Bentall Centre, Vancouver B.C., V7X 1N8, CANADA; see also
> www.taxapad.com
> 
> 
> -----Original Message-----
> From: taxacom-bounces at mailman.nhm.ku.edu
> [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Jody Haynes
> Sent: 22 January 2009 12:15
> To: Taxacom
> Subject: Re: [Taxacom] Polar bears as a subspecies or species
> 
> 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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> 
> 
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