RE: Ancestors... (was Re: Stratigraphy, biogeography & cladograms )

[Pharris Nicholas J <pharrinj@plu.edu>]

On Wed, 20 Jan 1999, Stewart, Dwight wrote:

> 
> 
>          Well, I think it's one caveat of species that the animals have to
> be able to produce viable offspring, naturally.  But, I took viable as
> meaning that
>       the offspring are capable of reproducing.  A mule is the sterile
> offspring of
>       a horse & a donkey.  I was taught that mules are sterile BECAUSE a
> horse &
>       a donkey are not the same species.  I'm sure if that isn't the case,
> there will be a zoologist on the list can give us the facts.

Well, I own a house cat who is also part leopard cat (_Prionailurus
bengalensis_), which is now widely recognized as belonging to a different
*genus* from the house cat _Felis sylvestris catus_--and he would be
capable of reproducing, if it weren't for the vet--so the rules about who
can produce fertile offspring with whom are a little more complicated  
than that.  Of course, felid species do tend to be rather conservative
genetically.

Perhaps Darren knows more about this than I?  I seem to remember a 
conversation with him along these lines...

Nick Pharris
Pacific Lutheran University