You wrote:

Rhinechis'd already been split off before Utiger et al.'s study, though, and, given the large amounts of both morphological and genetic disparity involved, I don't think there's much reason to doubt that the split was warranted.



My response:

Tong et al.'s analysis includes Elaphe mandarina, which is the basal most member of Elaphe. They find Ptyas, Zaocys et al. outside of the cluster of Elaphe species included in their study. Since E. mandarina is more basal than E. scalaris and E. scalaris is more basal than the New World species of Elaphe in both Utiger et al. and Lopez and Maxson, Tong et al. thus demonstrate that all species of Elaphe are more closely related to each other than any of them is to any of the racers.



According to you every taxonomic change that results in the removal of species from Elaphe is warranted. I have not seen one single change that you say is unwarranted. If one is going to blindly accept taxonomic changes, that is fine. Many people do it, including among them professional herpetologists.



You wrote:

So, is there any reason to suspect that this is the case in Elaphe sensu lato?



My response:

The unresolved polytomy only occurs in their consensus tree. The MP tree is better resolved. That shows there is something wrong with their data since the MP tree does not suggest adaptive radiation.



You wrote:

They can't show that, because they didn't study all Old World members of Elaphe sensu lato. Outgroup representation would also need to be much higher for this to be compelling.



My response:

The unusally high bar you have raised for Tong et al.'s data, which contradicts your preconception, is in sharp contrast with the blind faith you show on the other authors' taxonomic proposals splitting Elaphe.



You wrote:

Lopez and Maxson don't study all New World species that were in Elaphe at the time of their publication, so they don't demonstrate anything about all of them.



My response:

They demonstrate that Elaphe scalaris is basal to the North American species of Elaphe. That is one important finding. Utiger et al. sure included them all and they show that Elaphe is part of the monophyletic group, with E. mandarina the basal most member. They corroborate each other. Have you forgotten about Utiger et al.'s paper?



You wrote:

Furthermore, all studies of lampropeltinine phylogeny I've seen show Pantherophis to be one of the more derived clades within Lampropeltini.



My response:

Are you suggesting that Elaphe obsoleta is a descendant of Lampropeltis or Pituophis and that it is only convergently similar to Elaphe scalaris? Fact is, all species of Elaphe share similarities with each other and with Lampropeltis in hemipenial structure. Pituophis is more derived in this respect. If Elaphe obsoleta is descended from Pituophis and not vice versa, then Elaphe obsoleta would have to re-evolve the hemipenial structure that its Pituophis ancestor had lost. If Elaphe obsoleta is descended from Lampropeltis, then it would have to re-evolve the keeled dorsal scale that its Lampropeltis ancestor had lost. Part of the problem may be the studies you read, part of the problem may be your inability to infer relationships from the tree.



You wrote:

It's also worth mentioning that Ptyas is not the taxon most closely related to Elaphe sensu lato in Lopez and Maxson's study, so is not `the' outgroup.



My response:

Lopez and Maxson show that Ptyas is not even close to Elaphe. Utiger et al. also find that Ptyas is not closer to any Elaphe than other species of Elaphe. Tong et al. find the same thing. Unless you know of some other species that would make Elaphe polyhyletic, your slim hope that Ptyas would do that has evaporated.



You wrote:

Did Dowling et al. conclude that Elaphe sensu lato is polyphyletic



My response:

They cannot make that conclusion because they have no data to do it. They are merely speculating.



You wrote:

There's a large gulf between `convincingly demonstrated' and `speculated'. My guess is that Dessauer et al. fall into this gulf.



My response:

You guess. Dessauer et al. assume. Neither of you have the data to show that Elaphe is polyphyletic.



You wrote:

Which paper are you referring to, here? I'm guessing you're referring to the 1987 paper. As per my corrective post, the 1983 paper was what I was referring to.



My response:

Utiger et al. do not give the full citation for this paper so how can you be referring to this paper? Besides, the 1987 paper merely cite data from the 1983 paper. So, you are just hoping that the 1983 paper will deliver what the 1987 paper fails to. No dice.



You wrote:

AFAIK, it is the case that Dessauer, Minton, and Dowling believed that Elaphe sensu lato is polyphetic. They didn't dismantle the genus, however. My guess is that they thought that a revision of the genus should await more comprehensive and definitive studies.



My response:

Those studies are now available, and they show that, contrary to their speculation, Elaphe is in fact not polyphyletic.



You wrote:

Many taxa now known to be polyphyletic have been recognized. A couple examples that come to mind are Natrix, when it included Nerodia, and Coluber. The problems of Coluber still haven't been comprehensively addressed, though Schatti and Utiger (Revue Suisse de Zoologie, 2001; 108 (4): 919-948) have begun to sort it out.



My response:

That is not the question. The question was "Do you have any evidence that a polyphyletic taxon, any polyphyletic taxon, has continued to be recognized despite its polyphyletic status?"



You wrote:

If two groups form sister taxa (as you say Elaphe quatuorlineata and Lampropeltini do in Dessauer et al. (1987)), one by definition cannot be ancestral to the other. So, according to this phylogeny, Elaphe quatuorlineata cannot be ancestral to Lampropeltini.



My response:

Elaphe quatuorlineata is basal to New World Elaphe and Lampropeltis, Pituophis et al. in Dessauer et al. (1987).



You wrote:

If we take Lampropeltini and Elaphe quatuorlineata to form a monophyletic clade, then if Pantherophis and Elaphe quatuorlineata share similarities not found in a common ancestor, their similarities evolved once in an ancestor of Pantherophis and once in an ancestor of Elaphe quatuorlineata. Because Pantherophis is a derived taxon within Lampropeltini, if Pantherophis and Elaphe quatuorlineata share similarities present in a common ancestor their similarities arose once in a common ancestor, were lost in an ancestor to Lampropeltini, and arose again in an ancestor to Pantherophis. So you've got two state changes vs. three.



My response:

Which similarity is shared by Elaphe obsoleta and Elaphe quatorlineata but not found in their common ancestor? I cannot think of any. All of their similarities appear to be shared among all species of Elaphe, which means they probably originated in the common ancestor of all species of Elaphe.



I wrote:

`Most systematists would agree that New World Elaphe is descended from an Old World species of Elaphe. Most systematists would agree that Elaphe is not polyphyletic.'



You wrote:

Have you asked them?



My response:

Do I have to? Utiger et al., Lopez and Maxson and Tong et al. all show that Elaphe is not polyphyletic. There also does not exist any paper that shows otherwise, why wouldn't most systematists agree that Elaphe is not polyphyletic? Are most systematists as dogmatic as you?

[ Show Entire Thread ]