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Southwestern Center for Herpetological Research
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RE: An answer to one of A few Questions

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Posted by: CKing at Sat Nov 20 05:38:47 2004  [ Report Abuse ] [ Email Message ] [ Show All Posts by CKing ]  
   

Scott Eipper asked many questions of WW et al. as to why some localities were not sampled. Most likely it is because they either cannot obtain tissue samples from those localities or in their judgement the samples they have is adequate to address the question they are attempting to answer.

As to the following question, also asked by Scott Eipper:

"Why not use the Name Pseudechis pailsei instead of 'Pseudechis cf. australis' Mount Isa and Pseudechis rosignoilii for 'Pseudechis cf. australis' Irian Jaya."

This is an easy enough question to answer. WW et al. are adhering strictly to Hennigian classificatory convention of recognizing only "clades," or holophyletic groups, which means groups that consist of one single ancestor and all of the descendants of that single ancestor.

That means WW et al. will only recognize clades, but not paraphyletic groups. If the P1b clade is removed from the genus Pseudechis, the remaining species will not form a holophyletic group, since it will then consist of clades P3, P2, P1a and P1c, but not P1b. In the Hennigian's or cladist's jargon, Pseudechis minus P1b (or any other descendant group) would be paraphyletic. No self respecting cladist or Hennigian will ever do such an unthinkable thing as to recognize paraphyletic taxa, no matter how different the P1b clade is morphologically from the genus Pseudechis. WW et al. are no exception. This sort of behavior was predicted by me before I even read their paper. The cladists' dogmatic intolerance of paraphyletic taxa is perhaps one of most destructive forces facing taxonomy today.

Their decision not to use Hoser's specific names for the P1b clade is stated on page 8. Their analysis finds equivocal support for the "monophyly" (or holophyly) of the P1b clade. Hence to be safe, they have apparently decided to consider the P1a and P1b clades to be a single species, at least for now. Whether or not the P1b populations represent a different species from P. australis cannot be answered by the mtDNA data. Since 2 specimens of Mt Isa P. australis show a great deal of mtDNA divergence, it would be interesting to find out if these 2 specimens are from two geographically isolated populations or whether they are sympatric but fail to interbreed. Such data would be a lot better at answering the question of whether one or more species should be recognized in the P. australis complex than mtDNA data alone.


   

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>> Next Message:  RE: An answer to one of A few Questions - richardwells, Sat Nov 20 21:59:26 2004

<< Previous Message:  A few Questions.... - Scott Eipper, Fri Nov 19 18:31:16 2004