Centres of origin

Alec McClay alec at ARC.AB.CA
Mon Apr 22 09:52:45 CDT 2002


On Mon, 22 Apr 2002 07:52:52 -0400, John Grehan <jrg13 at PSU.EDU> wrote:
[John posted this in the thread on "Biogeography's aims" but I've taken the
liberty of replying in the "Centres of origin" thread as this is really the
same discussion.]
 >
 >My view is that it is possible to say something about the origin and
 >distribution of individual species with a scientific basis. Once one
 >defines a baseline, for example, one is providing a hypothesis for the
 >origin of the track and its constituent taxa (whether species or anything
 >else). Since the baseline is localizing the 'centre' of the origin of the
 >track, it is a sort of centre of origin, although not a Darwinian one.
 >
 >Most of what I understand abut the question of where did this species
 >originate is that it is in reference to members of a particular species
 >being located outside the range (as an exotic introduction) of the original
 >species range, and the interest is usually from what part of the original
 >species range did the exotic originate. There are assumptions of similarity
 >(e.g. genetic, morphological) along with various degrees of historical
 >information that may make that possible.

This is not quite the same question, although it's certainly one that is
also of interest when dealing with exotic species. A specific example of
your question would be "From what part of its native range in Eurasia was
[say] Cirsium arvense introduced into North America?". (Of course, if the
species was introduced on multiple occasions, the introduced population
could be derived from several different locations within the native range.)
It's not hard to see how this might be answered, based on genetic studies,
molecular and morphological evidence, historical records, etc. My question
is "Within the 'native' range of Cirsium arvense, can we identify some
area, more restricted than its current distribution, in which the species
had its evolutionary origin?". I suppose this is what you mean by a
"Darwinian" centre of origin, although I'm not sure if I understand the
sense in which you are using that term.
Alec McClay
Research Scientist, Biological Control of Weeds

alec at arc.ab.ca           Alberta Research Council
Phone (780) 632-8207     Bag 4000, Vegreville
Fax   (780) 632-8612     Alberta T9C 1T4, Canada

http://www.arc.ab.ca/




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