[Taxacom] New lizard species

[Richard Zander]

I think the attributes about the lizard species must be taken as coming from specimen attributes. The authors and apparently nearly everyone who reads this paper leap wildly to the conclusion that a DNA sequence represents a population or a species or whatever. This is a hidden assumption. I think this comes from the fact that a large proportion of sampled specimens in other published phylogenetic studies seem to have the same or similar DNA sequences per population or species, etc. Or at least they have different DNA sequences but cluster on a molecular cladogram. This is heartening, but . . .  It this proportion large enough to justify the widespread assumption that OTUs are valid exemplars of larger groups that include the specimen, in any particular case such that variation is trivial or can be ignored? I don't think so. 
 
Even if the sequences did differ per population as might be demonstrated with decent sampling, well, of course, they might, since the populations have apparently been isolated and nonsense mutations accumulate differentially in the different populations. This makes them different species? Again a hidden assumption obtains, namely that isolation invariably leads to speciation of both daughter species. 
 
So we have two hidden assumptions, which, along with a number of others, strongly affect the nature and credibility of the hidden structure that phylogeneticists assert they are discovering. Hidden assumptions, hidden structure. Well, is there hidden structure? Sure. I think research into constructing a Tree of Life is an excellent idea, and we should someday begin.
 
_______________________
Richard H. Zander
Missouri Botanical Garden
PO Box 299
St. Louis, MO 63166 U.S.A.
richard.zander at mobot.org
 

________________________________

From: taxacom-bounces at mailman.nhm.ku.edu on behalf of Dan Lahr
Sent: Tue 6/8/2010 10:08 AM
To: Kim van der Linde
Cc: Taxacom
Subject: Re: [Taxacom] New lizard species


[Extract:]

There is nothing fundamentally different in morphological versus
molecular interpretations, and although the argument that the lizard
papers insights come from populational attributes is valid, most
morphological interpretations are also referring to populations not
single individuals, as has been pointed out.