I have read somewhere that the majority of new species comes from
geographical isolation. At some point over the past millions of years a
group of Dowitchers became isolated from the rest of the Dowitchers. Over a
period of time (lots of time) their genetic make-up became distinct enough
that they were different from the original group. One of the final tests
would be that they became reproductively isolated. The offspring of the two
groups would be infertile.
As I write this I am reminded by the back of my brain that this is the
Ernest Mayr concept of species and has probably been replaced by a newer
concept of species. But I figure if I post this maybe it will prompt
somebody else to augment/correct my explanation.

Jim

PS And no, this explanation wouldn't fly in Kansas. Just to keep things in
perspective.

At 08:48 AM 8/13/99 -0700, Jack Stephens wrote:
>As I struggle to learn to distiguish similar species in the field, I began
>to wonder how they became separate in the first place. It seems obvious, for
>example, that Long and Short-billed Dowitchers came from a common
>ancestor. They overlap in range and appear to have similar ecologic niche.
>So what happened in the past to split them into two distinct species? Any
>thoughts?
>
>Jack Stephens
>jsteph02 at sprynet.com
>Edmonds, WA
>

Jim Rosso
Issaquah, Washington
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