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From: gmr044@leah.Albany.Edu (Gregg Recer)
Newsgroups: rec.pets,sci.bio
Subject: RE: What is a species?
Keywords: hypothetical arguments are just that
Message-ID: <2508@leah.Albany.Edu>
Date: 8 Feb 90 20:19:57 GMT
Organization: The University at Albany, Computer Services Center
Lines: 78




In article  <1990Feb8.100425.16932@newcastle.ac.uk>
J.M.Spencer@newcastle.ac.uk (J.M. Spencer) writes:

>In article <2495@leah.Albany.Edu> gmr044@leah.Albany.Edu (Gregg Recer) writes:
>>
>>
>>In article  <2285@uwm.edu>  debbie@csd4.csd.uwm.edu (Debbie Forest)
>>writes:
>>
>>
>>>yes, all dogs are the same species.  but why then aren't wolves in the
>>>species too, since dogs and wolves can breed.
>I believe that the domestic dog is a *sub-species*.  (Correct me
>if I'm wrong).
>>
>>
>>I don't know from what wild species domestic dogs were derived, but
>>even if it wasn't wolves dogs might still be able to breed with wolves
       ^^
>>and produce viable offspring.  
>It *was* the wolf.

Several people have pointed that out; I simply didn't know.

>>However, those offspring would then be
>>infertile.  This same kind of mating barrier occurs in the
>>horse/donkey/mule system. 
>I'm not convinced that a dog-wolf cross *would* be infertile.  Do
>you have any references? 

Notice that above I said _if_ dogs were not derived from wolves.
Given that assumption (which proved to be wrong) the fact is that the
rest of my argument then holds.

>
>>Some general remarks:
>>
>>In many cases, including dogs and cats, a large number of breeds or
>>varieties have been produced via artificial selection from a single
>>wild species.  In some cases, such as the St. Bernard/Chihuahua
>>example a mating barrier has been established via artificial
>>selection.  
>I don't buy this.  Both *breeds* belong to the same *species*.
>Therefore they carry the same genes, right?  Therefore, in theory
>at least, they should be able to breed.  Unless you are meaning
>that they *physically* couldn't manage it?  If you do, then that
           ^^^^^^^^^^^^^

precisely what I meant -- i.e., morphology barrier

>has nothing to do with genetics/species, does it?

Yes.  Species are defined by the presence of some kind of mating
barrier between them.  The definition of mating barriers is somewhat
blurry but usually is agreed to include morphological, behavioral and
physiological differences as well as genetic ones such as different
chromosome number.  It can also mean interbreeding but producing
infertile offspring as described above.  Remember that the concept of
species has been around a lot longer than any of our concepts of
genetics.



Gregg



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     "In future you should delete the words crunchy frog and 
     replace them with the legend crunchy raw unboned real
     dead frog!!"  
                 -- Inspector Bradshaw, The Hygiene Division

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