"The ICZN rules deal with Nomenclature not systematics. Therefore wether there is a requirement under the ICZN to deal with paraphyly or not is irrelevant."

Whether paraphyletic taxa are recognized or not is a taxonomic (nomenclatural) issue, not a systematics issue. A Darwinian (traditionalist) and a Hennigian (cladist) looking at the same tree may classify the animals quite differently depending on whether they tolerate paraphyletic groups or not and whether they take into account morphological disparity in their classification or not. Since the ICZN is silent on the issue of paraphyletic taxa, there is nothing in the rules that requires the destruction of paraphyletic taxa. The decision to splinter paraphyletic taxa is entirely that of the individual taxonomist. Therefore whether one accepts a proposal to reclassify animals on the basis of an intolerance of paraphyletic taxa is entirely up to the individual as well.

"I am not personally in favour of the use of DNA sequence data in systematics, as I am a taxonomist/ palaeontologist I see it to be useless as the majority of the testible taxa return a
non-result. Hence I think DNA has its place in population studies and other below species work."

DNA data may be useless to most paleontologists in most cases, but they have proven useful in some exceptional cases. For example, a recently published paper (Burger et al. 2003) dealt with the relationship of extinct cave lions by examining their mtDNA. Much older (20 million years) DNA preserved in the form of fossil leaves have provided invaluable insight for both paleontologists and evolutionary biologists. S. J. Gould, for example, dealt with the discovery of ancient DNA in his essay "Magnolias from Moscow" in the book "Dinosaur in a Haystack." It would be a mistake to dismiss DNA data simply because it is not a geologically stable molecule and hence is absent from most fossils, as big a mistake as it is to ignore the details of soft tissues that are occasionally preserved in exquisite detail in some fossils.

In many cases, the classification of animals is difficult because there are few morphological similarities and the high probability of convergence of morphological characters. The relationships among Burgess Shale organisms, if they had living descendants, would have been much clearer since their DNA can then be sequenced. DNA sequencing successfully resolved the relationship between the king crab and a single genus of hermit crabs. Morphological data alone would not have been able to do the same. In fact, the close relationship between whales and the artiodactyls was discovered long before the leg bones that confirm this relationship was finally found. As S.J. Gould points out, DNA sequences provide "an enormous increase in the number of useful characters for classification." I know of no scientist who is not elated by an abundance of data since they are most often frustrated by a lack of same. There can never be too much data if one is a scientist.

It would not be an exaggeration to say that DNA data revolutionized systematics. Cladistics, however, has done the opposite, as it has brought systematics back to the days of pre-Linnaean facile diagnosis. Cladistics was embraced by the morphologists because they desperately needed something to counter the ongoing revolution brought on by the increasing use of biochemical data, which threatened the morphological systematists with extinction. Sadly, one well known and highly respected herpetologist even committed suicide because he thought that there will be no place for the morphological systematist in the future. Paradoxically, many molecular systematists have unwisely allied themselves with the Hennigians (cladists), even though molecular systematics owes nothing to the Hennigians because it was developed independently of cladistics. Consequently, many molecular systematists are unwisely following the dictates of Hennig and are on a crusade to destroy paraphyletic taxa and replace them with contrived taxa that cannot be consistently defined.

Systematics has taken a giant leap forward in the use of DNA sequences but sadly taxonomy has taken a giant leap backwards at the same time because many taxonomists have become Hennigians.

Reference

Burger, J. et al. 2003. Molecular phylogeny of the extinct cave lion Panthera leo spelaea. Molecular Phylogenetics and Evolution (in press)

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