"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 system of nomenclature is independant of methodology. The methods employed by the research and the paradigm they work from is the science. Nomenclature is not a science. It is the application of a set of rules to a situation. It is about the validity of the publication of names and how they should be applied. It has nothing at all to do with how the relatedness of the taxa involved is determined.

As such what you are referring to is methodology of tree building and interpretation. This is systematics.

I can see your argument, you basically are from a different paradigm as the vast majority of taxonomists recently and are building arguments to justify your stance. Thats fine, all scientists do this. I am not saying you are wrong. I happen to also think that cladistics has more a kin to a religous fervour than to science. But I live with it.

"DNA data may be useless to most paleontologists in most cases, but they have proven useful in some exceptional cases."

Exceptional cases while interesting do not help the majority of science.

"It would not be an exaggeration to say that DNA data revolutionized systematics."

Of course it isn't, I never denied it has been used, and as I have used allozyme electrophoresis and DNA sequencing in my own papers I would be a fool to say it could not be used. I just wonder at its validity in Systematics and wether we are making a mistake to utilise it so much. I have argued that considering every single locus as a character is a mistake because of the inherit protection systems in genes where limited point mutations can be present without effecting the gene. I also worry about the vast regions of "unknown", presumably non-coding areas that are used. But these are all parallel arguments.

Also one of the biggest difficulties with cladistics is weighting. If you sequence a gene and come up with several hundred characters and then combine it with a morphological annalysis with say 50-100 characters you have a weighted and biased dataset, biased to DNA as it swamps the dataset. Geneticists argue that the morphology should be excluded altogether and later mapped on to the gene sequence trees and that fossil evidence should be excluded altogether as well. Personally I call this manipulation of data.

"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."

Well I think it has taken a leap sideways myself and I think it needs another 20 years or so before it gets understood what is happening and reigned in a bit. As for a backwards step in cladistics, again I think this depends how it is applied. Numerical Cladistics I would certainly agree with you. The deliberate attempt to turn systematics into a pure popporian science has done a lot of damage. However, there are alternatives and some are being developed.

Cheers, Scott

[ Reply To This Message ] [ Subscribe to this Thread ] [ Show Entire Thread ]