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Posted by WW on February 27, 2003 at 07:00:52:
In Reply to: Indigo Snake Systematics...very nice update WW, thnx.... posted by regalringneck on February 27, 2003 at 06:18:26:
:Nice series of photos.
:As I said earlier, I'd prefer to see a larger sample size,
So would I.... but beggars can't be choosers ;-)
: but your argument is a reasonable one. The lack of face & neck slashes pushes your beast towards corais corais,
Agree - I suspect it is closest to D. corais and D. margaritae than to the C. and N. American forms.
> & I'll bet you a pint that somewhere to the East/Southeast theirs a cline.
Hmmmm - I'l hold you to that, because I am not so sure about that. After all, as evidenced from the PCA analysis, D. corais is pretty uniform all the way from N. Venezuela to at least SE. Brazil - it would seem strange that it should be uniform over 1000s of miles,a nd then sudenly show a steep cline to a very strongly differentiated form within a very short distance in NW Venezuela.
:I guess what I'd like to hear is your definition of a species...
An independently evolving lineage. The major question, of course, is defining "independently evolving" and what evidence is required to fulfill that criterion.
Personally, when I see two "forms" such as melanurus and corais, which are morphologically +/- invariant over vast ranges, consistently distinct, and sympatric in N Venezuela, and approaching a third, equally distinctive form, then to me, the most parsimonious interpretation is that they are 3 species. After all, what evidence is there that they are NOT separate species? Sure, it's a hypothesis that should be tested, but with the evidence available at the moment, the multiple species hypothesis seems the most parsimonious interpretation.
I am hoping to do a DNA follow-up, as well as a more comprehensive morphological study of the entire genus one of these days, but at the moment, I don't have samples for enough taxa. Too many snakes, too little time, to quote Rick Shine.
Just a few thoughts...
Cheers,
Wolfgang
