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Posted by WW on October 17, 2002 at 11:10:33:
In Reply to: Re: Taxonomy is a matter of evidence...most of the time posted by Langaha on October 17, 2002 at 09:35:53:
:This Elaphe obsoleta revision has led to a lot of controversy and no one I know has accepted it. How can one justify sinking subspecies and elevating some to species based on a single slowly-evolving mtDNA gene? Population structure certainly does not necessarily indicate a distinct species, and thier data proved that their "species boundaries" failed to hold up (i.e. Apalachicola River). A total misuse of the ESC as well as mtDNA! And we thought subspecies have been used inappropriately.
Let's make a distinction between sinking the ssp. and describing the mtDNA clades as separate species. Burbrink et al.'s study showed extremely convincingly that the conventional subspecies are not real evolutionary entities - they have been blown out of the water, both by morphology and by mtDNA, end of discussion.
However, I don't think the E. obsoleta study adequately documents that we have three full species. The mtDNA pattern certainly gives part of the story, and represents a history of past separation between the four clades, but it does not demonstrate that gene flow between them is negligible today, and that they are really two separately evolving entities. His morphological analysis does not do so either - we have had this discussion on this forum before.
Even so, thanks to those studies, we know a heck of a lot more than we did before about what is going on in Elaphe obsoleta. We may not agree with some of the conclusions, but we do now have a firm phylogeographic background from mtDNA which can be compared with new evidence.
Cheers,
Wolfgang
