I always have this uncomfortable feeling about cladistics that it's really some kind of trick or hoax. That is, correct me if I'm wrong, but I understand it to be a scheme that maps traits and finds that they follow the pattern of the taxonomic tree.
You are wrong.
Early taxonomic systems and the original linnean system are rather crude precursor forms of cladistics. Living things were categorised based on apparent similarities.
What cladistics does is to produce a much more formalised and rationalised taxonomic tree based on specific shared traits known as synapomorphies which is a phylogenetic tree rather than merely taxonomic.
Synapomorphies are traits which are common to one or more taxa (taxa is the plural of taxon, a taxon being a specific grouping of organisms) and which are thought, or known, to be inherited from a common ancestor.
A taxonomic tree simply categorises into nested hierarchies, a phylogenetic tree contains inferences about the common ancestry of organisms based on synapomorphic characteristics.
The strength of the evidence that Modulous has been discussing is that independent Genetic traits, such as those involved in basic cellular metabolism, which do not affect the synapomorphic morphological characteristics which have been used to produce traditional cladistic analyses, produce remarkably consistent results when used as the basis for cladistic analysis.
So both the morphological cladistic analysis and the cladistic analysis of genetic sequences produce similar phylogenetic trees despite being as independent a measure as possible.
An argument can of course be made that this is all down to 'common design' but this is an
ad hoc argument with purely explanatory and no predictive power.
Someone who believes in common descent would have good cause to predict that genes with no effect on morphology would produce the same patterns through cladistic analysis as would analysis of morphological characteristics or the genes controlling them since they have all been inherited through the same ancestors. What would compell a believer in common design to make such a prediction?
TTFN,
WK
This message has been edited by Wounded King, 22-Feb-2006 12:42 PM