Linda,
alas, things are not always so simple in nature as our limited human mind
would like them to be! Populations can be separated by long distances, or by
sexual isolation mechanisms, different species can, like in the case of
European frogs, interbreed, produce a third fertile species as hybrid, yet
keep their characteristics as separate species. Then there are cases of
species which form different subspecies over their geographical range of
which some do not interbreed anymore when their ranges overlap like in the
case of the Herring Gulls (Larus fuscus and Larus argentatus). What we can
probably say is, that in a continuum of living beings there are limits where
genetic exchange is markedly reduced, most often to virtually nothing, and
these boundaries delimit what we call a species.
Greetings from Germany
Michael
----- Original Message -----
From: "lindawbush" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, February 10, 2003 3:05 PM
Subject: taxonomy


> Okay, I'll bite!
>
> Much of taxonomy does NOT exist in nature - categories
> such as Genus, Family, Superfamily, Order, etc. have been
> invented for our sense of needing to put order in our view
> of nature.  HOWEVER, I thought that the original concept
> of "species" is the only thing which does exist, harking
> back to the initial definition of individuals which are
> able to mate with each other and produce fertile
> offspring (and thus eliminating crosses producing animals
> such as the Missouri mule, which is a cross between a
> horse and a donkey but is sterile).  Granted, this
> definition of species has been extended to geographically
> isolated populations which could not breed anyway because
> they would never get toghether (but what would happen is
> we were able to keep a pair of these separated "species"
> alive in an aquarium)?
>
> Doesn't this definition still hold as a natural fact, thus
> validating the concept of species as not an invention by
> man to simplify his thinking about life in genera
>
> Needing a cup of coffee to clear the cobwebs,
> Linda
>