Wolfgang wrote:

Splitting needs to me justified on PHYLOGENETIC grounds - what data were used the generate the phylogeny does not matter, and there is no need to invoke morphology (although, in the long run, studies based on a maximum of evidence are likely to yield the most robust phylogenies.



My response:

I do agree that taxonomy should be based on phylogeny. We simply disagree on the definition of phylogeny. Utiger et al. do take into account morphological disparity, otherwise they would be unable to tell whether two terminal nodes on their cladogram really represent two populations of the same species or two different species. If morphology cannot be taken into account, then every one of their terminal nodes can be treated as a distinct species or even genus. Hence it is blatantly disingenuous to claim that cladists do not rely on morphological distance. They do rely on it, but their reliance is inconsistent. If they truly ignore morphological disparity, then they may have to rely on Hennig's rule that sister taxa be given equal rank. Utiger et al. seem to be following that rule for most of their tree, but they abruptly depart from that practice in the Lampropeltini part of that tree. If they follow their rule, they should have given equal rank to Euprepiophis and its sister taxon. If Utiger were relying only on "phylogeny" then there should only be two genera: Euprepiophis and Elaphe. The alternative is 76 genera, one for each terminal node in their cladogram. Obviously, cladists cannot completely ignore morphological distance. They just have to selectively ignore it in order to classify organisms according to Hennig's scientifically untenable classificatory philosophy.



Wolfgang wrote:

In other words, morphological *characters* are a perfectly good source of data, morphological *disparity* is not.



My response:

Morphological disparity cannot be ignored in taxonomy. I have shown that cladists cannot completely ignore it. You are suggesting that morphological disparity cannot be used in ascertaining branching order. That I do agree with since the rate of morphological evolution is different within and among different lineages. However, once branching order is ascertained, morphological distance can indeed be taken into account in delimiting taxa and ranking taxa. Cladists prohibit such practice but they do have to ignore their own prohibitions. Otherwise, they cannot possibly distinguish two populations of the same species from 2 different species.



Wolfgang wrote:

I dare say Darwin himself would be rather disappointed if nobody had developed his ideas further since his death.



My response:

Darwin would definitely be disappointed because the Hennigians are simply ignoring his ideas. That has led to a split among taxonomists: one school following Hennig and calling themselves cladists and another school following Darwin, and calling themselves Darwinians or the evolutionary school. The Hennigians have not developed Darwin's ideas. The Hennigians are simply reverting to pre-Darwinian taxonomic practice. The cladists are as far apart from Darwinism as are the Lamarckians.



Wolfgang wrote:

I am hardly a hard-core ideological cladist when it comes to taxonomy, and am in fact far more concerned about stability of the nomenclature than many of my colleagues. I even agree with of your comments re Kluge's reclassifications of erycines and Boa/Sanzinia/Acrantophis (which were in all other respects excellent studies at the forefront of the subject), but not, for instance, with your views re Chondropython, which was quite rightly sunk into Morelia by Kluge in another one of his excellent studies.



My response:

Your philosophy seems to be pretty ideological since you ignore the large amount of morphological disparity between Chondropython and Morelia and you support the splintering of Elaphe even though these snakes form a rather homogeneous group in terms of morphology. I agree that you may not be as "hard core" as some of the hard line cladists, because they themselves would have rejected Utiger et al.'s classification. As I said, Kluge dumped all species of his polytomy into Eryx. He would probably have done the same with Elaphe, given his similar dumping of Chondropython into Morelia. Utgier et al. depart from established cladistic practice of equal rank for sister taxa, but their classification is also not Darwinian because they also ignore morphological disparity for the most part. Utiger et al.'s taxonomic arrangement is therefore both scientifically AND cladistically untenable.

[ Show Entire Thread ]