You wrote:

You're saying that it's premature to assert that Elaphe is polyphyletic until we have data demonstrating that Elaphe is not polyphyletic? This amounts to an a priori rejection of the possibility of polyphyly.



My response:

I do not reject the possibility that Elaphe is polyphyletic. I reject your assumption that Elaphe is polyphyletic. You are assuming polyphyly since you have no evidence of polyphyly. There are three independent studies showing that Elaphe is not polyphyletic. That is strong evidence against your assumption of polyphyly.



You wrote:

Utiger et al. do, however, cite other works which demonstrate that Elaphe sensu lato is a morphologically disparate group. See, for instance, Helfenberger, N. `Phylogenetic Relationships of Old World Ratsnakes Based on Visceral Organ Topography, Osteology, and Allozyme Variation', Russian Journal of Herpetology 8 (Suppl.) 1-64.



My response:

There is no evidence that they rely on these types of evidence in delimiting their taxa. They delimit their taxa strictly according to their consensus tree, which is poorly supported by your own admission. Their taxa are therefore poorly supported.



You wrote:

Out of curiosity I got hold of the Lopez et al. (Lopez, Maxson, and Dowling) paper, and found the following:



My response:

You have the wrong paper. The correct one is Lopez and Maxson's 1995 study comparing mitochondrial DNA among ratsnakes and racers. They compared the mtDNA of N. American and Eurasian Elaphe with those of a large number of racers. All of the racer species are basal to Elaphe in their tree. Since racers are the sister taxa of the ratsnakes, this is a good test to see if different species of Elaphe are in fact only convergently similar. If Elaphe is polyphyletic, some species should be closer to some of the racers than they are to each other. This is clearly not the case. All species of Elaphe form a clade along with Cemophora, Lampropeltis and Pituophis.



You wrote:

Your assessment of two of those studies disagrees with that of their authors. Including the other papers cited by Utiger et al. and mentioned elsewhere in the thread demonstrating polyphyly of Elaphe sensu lato, this gives a total of 5 independent studies demonstrating polyphyly of Elaphe sensu lato and 1 disagreeing.



My response:

In some of these papers, the authors merely assume that Elaphe is polyphyletic. You are placing too much weight on these papers that you have not read. Whatever weakness the Acta Zoologica Sinica paper may have is adequately addressed by the paper of Lopez and Maxson. They include a large number of racers and find that none of the species of Elaphe cluster more closely to any of the racers than they do to each other. This is clear evidence that Elaphe is descended from a single species of racer; the ratsnakes are monophyletic. The morphological similarities among all species of ratsnakes are therefore shared derived characters, not convergences. Elaphe is paraphyletic according to the cladists because some of its descendants, such as Lampropeltis and Pituophis, have been removed from Elaphe on the grounds of morphological disparity. Paraphyly is the reason Utiger et al. are applying their machete to Elaphe, not because Elaphe is polyphyletic, since there is no evidence of polyphyly in their paper. Utiger et al. concede that paraphyletic taxa is the inevitable result of evolution, but it has not stopped them from splintering Elaphe because it is paraphyletic. Darwinians, on the other hand, insist that disqualifying or splintering paraphyletic taxa is scientifically untenable. I concur.

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