common names/systematics

DR. JAMES ADAMS jadams at
Thu Jun 10 10:47:41 EDT 1999

John Grehan writes, about species concepts:

> The former concept is essentialist in that it requires spatiotemporally
> unrestricted essences that are true for all places and time (which is
> kind of anti-evolutionary since essences can't evolve) and includes
> phylogenetic species concepts and biological species concepts. Only 
> the species as individuals concept allows for evolution. 

I would argue that species are probably rarely actually treatable as 
individuals.  What probably really *does* respresent  evolutionary 
individuals are *populations*.  I don't truly believe that a 
widespread species has enough gene flow so that if major climatic 
change takes place all populations will respond all in the same 
fashion, as a single unit.  It is different *populations* of a 
species that are potentially under different selective pressures, and 
only if the species is represented by one population only will the 
*species* respond as an individual.  If there is a very broadly 
dispersed population of a species, then widespread gene flow actually 
*resists* change within smaller subsets of that population.  At any 
rate, I doubt that species are truly *evolutionary* individuals in 
most cases.


Dr. James K. Adams
Dept. of Natural Science and Math
Dalton State College
213 N. College Drive
Dalton, GA  30720
Phone: (706)272-4427; fax: (706)272-2533
U of Michigan's President James Angell's 
  Secret of Success: "Grow antennae, not horns"

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