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Molecular systematics - is it all rubbish?

Petur Henry Petersen php at rhi.hi.is
Wed Jun 14 06:42:25 EST 1995


In <3rldgd$f10 at studium.student.umu.se> Agneta Guillemot <Agneta.Guillemot at historia.umu.se> writes:


>But it is'nt koscher. Why? There is one vital factor that molecularr 
>systematicists never seem to take into account in their work:  
>Different species evolve at different rates at different times. 
>Evolution is'nt just a clockwork that goes on and on. What if,  

	I would like to think it does _some_ of the time. Specially
when we are talking of neutral changes in molecules. Of course evolution
of quantitative characters is not a clockwork (most of the time).
I think that this is the reason different molecules are chosen for different
phylogenies.

>Let's face it: Evolution in a species slows down and speeds up at 
>different times. Some species are left in the backwater, others 
>evolve fast in new evolutionary niches. There is no way of knowing 
>what happened when. The molecular clock does'nt exist! 


>There is only one school of systematics whose theorethical basis 
>is untouchable. It is of course cladistics. If you apply cladistic 
>methodology to sequence data you come to the right, unquestionable 
>conclusions. Most molecular systematicists seem to ignore cladistics. 

	 I think molecular systematics are well aware of cladistics and
dont ignore them though they might use other methods since they have
different data. I think it is hard to use cladistics on DNA (or what?).
What do you mean with cladistic methodology to sequence data?

	P. "hopethisisnotaflaimebait" Henry Petersen
	php at lif.hi.is



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