WW:
All the mtDNA sequences really tell us is that there has clearly been recent and extensive gene flow between the two. It is of course possible that the Aussie and NG populations have been in situ much longer, but that introgressive hybridization swamped out the mtDNA haplotypes of one of the two populations, while other alleles were retained - we can't tell, at least not from our current sampling, which is also why we did not sink canni formally. Other molecular methods (e.g., AFLPs) would certainly be of interest also.

Me:
I wouldn't say that. If one of these two localities was not occupied by snakes within this complex, then all that the mtDNA data tells us is that there had been a recent migration from one locality to another. Migration into a previously unoccupied area should not be called gene flow between two populations. If a single gravid female or only a few individuals migrated to a new area and never interbred with any individuals of the ancestral population, then there is technically no "gene flow" between the new population and the ancestral population. Further, if only a few individuals migrated, then founder effect divergence may result in rapid morphological divergence, as can adaptation to a new habitat.

WW:
Obviously, whether one chooses to recognise Parademansia as a separate genus or not based on morphological differentiation is, at the end of the day, a purely personal and arbitrary decision.

Me:
The recognition of a new genus on the basis of mophological disparity is indeed subjective. However, the grouping of taxa on the basis of holophyletic groups is even more subjective. As Kluge pointed out in his classification of "Charina," he could have recognized either one, two or three genera for the 3 species he was classifying. His decision to recognize only one genus for these 3 species is purely personal and arbitrary even by his own reckoning. His decision is based on "taxonomic efficiency," which is of course subjective and arbitrary.

Richard Wells:
> As for "Pseudechis" well as I have long maintained, the traditional use of this genus for that assemblage of species makes no ecological or morphological sense at all. I still hold the view that Pseudechis contains only the porphyriacus populations. The australis members (except the weigelli
complex) should be placed within Cannia.

WW:
For Pseudechis, we went with nomenclatural stability. I agree, P. porphyriacus is very distinct indeed genetically from the other species of the genus, but since our data did not provide clear evidence that it is NOT monophyletic, since there is some morphological evidence indicating monophyly of all Pseudechis, and since others are working on this, we left it in the traditional way.

Me:
Taxonomic stability is not always on the top of the list of WW's reasons for supporting a taxonomic proposal or not. For example, Utiger et al.'s proposed splintering of the paraphyletic Elaphe was fully supported by WW, even though it will create taxonomic chaos by the truckload. Similarly, Kluge's lumping of Morelia and Chondropython into a single genus and Kluge's lumping of Charina, Calabaria and Lichanura into another genus were both fully supported by WW. As long as a taxonomic proposal conforms to the cladistic intolerance of paraphyly, it appears that WW will tend to support it, regardless of whether the proposal will result in taxonomic stability and regardless of whether the proposal represents excessive lumping or excessive splitting. However, if someone, anyone, were to propose a taxonomic rearrangement that will result in the recognition of paraphyletic taxa, it is almost a sure bet that WW will oppose it.

WW:
Heck, I could even countenance recognising Panacedechis for
guttatus, colletti and papuanus if Pseudechis is going to be split at all. However, I don't see anyreason to place the various weigeli, pailsi, rossignolii etc. into a separate genus from Cannia - they are similar enough to australis (which is why we regard them as different species), and the evidence for the monophyly of "Pailsus" is practically non-existent in any case.

Me:
Of course WW will support recognizing guttatus colletti and papuanus as a genus since these three species form a neat little holophyletic group in his cladogram. He cannot, however, support the recognition of "Pailsus" because doing so will render Pseudechis paraphyletic. I am not arguing that Paisus should be recognized or not. That decision should be left to those who are experts in this taxon. If someone presents good evidence to show that it is evolutionarily divergent from Pseudechis, then I would definitely support its recognition, even if Pseudechis will be rendered paraphyletic. On the other hand, as I pointed out elsewhere, even if "Pailsus" were to evolve a shell and a beak, the cladists and WW would oppose recognizing "Pailsus" as a separate genus from Pseudechis, unless Pseudechis is also broken up into as many holophyletic groups as necessary so that no paraphyletic group will result from the recognition of "Pailsus." Therein lies the difference between WW and the cladists on the one hand and the Darwinians and I on the other hand. There is no middle ground between these two incompatible classificatory philosophies. That is why WW and I will continue to disagree on most taxonomic matters for the foreseeable future.

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