>
>Now, regarding _cline_: A cline exists within a species when there is a
>gradient of form across a geographic range. For instance, there seems to
>be a cline in the Song Sparrows along the Pacific Northwest coast, as the
>birds get larger and darker from south to north. The species is formally
>divided into a few named subspecies across that range, and I'd leave it
>to someone who's an expert on the species to say whether that division is
>realistic or whether the morphological changes are quite continuous
>across that range.
>

And the oft cited article on West x GW Gulls in _the Condor_ clearly
demonstrates a cline as does Johnston's work on Northwestern Crows.
By my understanding of _biological_ species neither of the should even
rate the semispecies definition (at least no more so than your Song
Sparrow reference).

Of course if one looks at things from the phylogenic perspective....



--
*********************************** I was of three minds
* Mike Patterson, Astoria, OR * like a tree
* mpatters at orednet.org * in which there are three blackbirds.
*http://www.pacifier.com/~mpatters* -Wallace Stevens