You wrote:

Utiger et al. also include many taxa not included in Lopez and Maxson's study, or any other studies I've seen of colubrine phylogeny, such as the members of Euprepriophis and Othriophis. If Elaphe sensu lato is mono- or paraphyletic, inclusion of these taxa shouldn't result in reduced support for the outgroup status of Ptyas. Yet their inclusion does reduce this support. I know what my conclusion is.



My response:

They do include more species of Elaphe than Lopez and Maxson, but their finding is the same as that of Lopez and Maxson: Elaphe is not a polyphyletic group. If it were, I would support dismantling it. Since it is not, I disagree with Utiger et al.'s splintering of Elaphe based on the Hennigian intolerance of paraphyletic taxa. As for the systematic status of Ptyas in reference to Elaphe, there is little doubt that Ptyas is an outgroup. Lopez and Maxson's study shows that it is closer to Coluber constrictor and Masticophis than to any species of Elaphe, New World or Old World. And I finally found a copy of Tong et al.'s paper in Acta Zoologica Sinica. They find a bootstrap value of 98 for the split between Ptyas and Elaphe, including the most basal member of Elaphe in Utiger et al.'s finding--Elaphe mandarina. See the "photo" below of part of their tree. They also found that Viperidae is sister taxon to Colubridae plus Elapidae, which is the same result that Wilcox et al. (2002, Molecular Phylogenetics and Evolution 25: 361-371) obtain. That shows Tong et al.'s data is corroborated by another independent study. Tong et al. also find E. mandarina to be the most basal member of Elaphe, corroborating Utiger et al. Tong et al. thus corroborate Lopez and Maxson, and both corroborate Utiger et al. All three studies strongly suggest Elaphe is not polyphyletic and that Ptyas is an outgroup to Elaphe. If your conclusion is that Ptyas is not an outgroup with respect to Elaphe, then I am afraid that your conclusion is independent of evidence.

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