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Posted by WW on May 06, 2002 at 12:09:56:
In Reply to: Re: Cannia australis and "Pseudechis".....more posted by Scott Eipper on May 06, 2002 at 06:15:32:
Thanks for the info!
: I can see your point of view, Taking the conservative and at the moment generally accepted view.
: Pseudechis I personally believe should be used for P. porphyriacus (which in itself, has a number of separate populations). It being viviparous and the rest of the genus being oviparous is a fair start in different snakes, as the internal reproductive system in the female snakes I would think would be some what different.
Actually, the viviparous/oviparous difference is a lot less of a major difference than you might expect - this can vary even within individual species - for instance, both Lacerta vivipara in Europe and Lerista bougainvillei in Australia have both viviparous and oviparous populations within the one species! Viviparity is really not much more than retaining eggs until the time of hatching, so the differentiation required is actually relatively minor.
: Also in many ways the snakes themselves are different. P. porphyriacus is generally a riparian species while the others are more generalistic. It is definatly true however that Mulgas and Spotted Blacks are found in Wet areas (Mulgas around Fogg Dam (N.T), and Spotted in and around the Maquarie Marshes and Gundy (N.S.W)).
The real acid test is not the level of differentiation, but phylogeny - what are the monophyletic groups? The scenario you suggest (Pseudechis for porphyriacus and Cannia for the others) is actually consistent with that, but it has little to do with levels of differentiation, and everything with which groups are monophyletic.
: I am personally of the view that P. australis, P. butleri, P. colletti and P. papuanus are of one genus (Cannia)and that P. porphyriacus retains its the previous Generic term Pseudechis.
: P. guttatus is also somewhat of a problem, but I am of the belief that it is also Cannia, due to its distinctive staining section of Chromosome 5 and is very closely allied to P. colletti because of this feature.
: P. guttatus and P. colletti have cross bred in captivity and I have recorded them as fighting (Male combat) with 2 males (One a Collett and one a Spotted).
I am not surprised - the level of mtDNA sequence difference bewteen guttatus and colletti is quite remarkably small - 1.7% in ND4 - this sort of level is more usually associated with variation WITHIN rather than BETWEEN species. If I didn't know the snakes better, I would have thought that they are one and the same species from that data. These two species obviously diverged from each otehr very recently.
: I just felt that I might clarify why I have came to my conclusions.
: Hope this was helpful,
Very - thanks a lot!