[Tweeters] RE: Notes on Cordilleran vs Pacific-slope in Latah, Nez Perce, and nearby counties - in response to the splitters

Nigel Ball nigelj.ball at gmail.com
Tue Jul 15 08:30:03 PDT 2014


I am not an expert, but I do familiarize myself with some of the technical
literature, and I can say with certainty that I don't have a clue as to
what constitutes a 'good' species.

We are hugely fortunate to live in an area where the manifestations of
evolution in action are writ large. So many distinct subspecies, forms and
inter grades! Wondrous, really.

I'm in favor of any system that addresses that complexity and allows the
community to communicate. I disliked it when, for example, no one recorded
Herring vs. Thayer's gulls because they were 'the same species'.
Conversely, I dislike the separation of American from Northwestern Crow
purely on geographical terms.

I think that ebird will eventually standardize 'identifiable birding
units', perhaps even by location and time of year, and we will all be
happier. Even the listers. Until then, I'd caution those of us who are not
professional evolutionary biologists against a focus on 'do I consider it a
species' and more on 'what is the best name/ id (species, subspecies, form,
race, whatever) that I feel comfortable assigning to that fascinating bird
in front of me.

Nigel Ball
Nigelj.ball at gmail.com
On Jul 15, 2014 7:44 AM, "Kelly Cassidy" <highsteppe at icloud.com> wrote:

> I don't have a strong opinion on the Western Flycatcher split (although,

> being a "lumper" at heart, my initial reaction is skepticism at the split).



> However, someone, (Doug, I think) commented that the DNA evidence was

> objective, or at least more objective than the morphological evidence. I

> agree that DNA evidence is more *quantifiable* than morphology. "Region

> X of the DNA sequence differs by Y% between population A and B" etc.


> But is it better at defining species? Well, maybe, maybe not. There is a

> lot of disagreement among biologists about that. Some very distinct

> species may have relatively few differences in DNA, but those differences

> are so critical (e.g., sequences that affect phenology of breeding) that

> they substantially affect hybrid viability. On the other hand some

> unambiguous species may show substantial DNA differences but the

> differences are evidently are not so critical. The DNA evidence is part of

> the story, but not the whole story.


> IMNSHO, the gold standard for vertebrates (who the heck knows about

> bacteria and such) is not DNA or morphology, but whether hybrids have

> reduced viability in the hybrid zone. That sort of thing can be difficult

> to measure in the wild, but a broad hybrid zone with most of the

> individuals in the hybrid zone being intermediate between the "pure"

> populations suggests, to me, that the species should not be split.


> Kelly Cassidy

> Pullman, WA



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