[Taxacom] Intuition in taxonomy

Peter Stevens peter.stevens at mobot.org
Thu Mar 5 09:22:11 CST 2009

I just happened to be reading a nice paper by Markmann and Parniske  
in Trends in Plant Science 14: 77-86. 2009 getting at the issue of  
nitrogen-fixing nodule formation in angiosperms (restricted to only  
four orders that form a clade, evolved several times with several  
different organisms).  In this case at least, the problem - basically  
that of an underlying synapomorphy - is yielding somewhat to  
dissection at the molecular level.

Similarly, the term "intuition" needs dissecting at the cognitive level.


On Mar 4, 2009, at 1:27 AM, Torbjørn Ekrem wrote:

> Hi Bob
> what you state here sounds a lot like 'underlying synapomorphies', a
> term coined by Ole Sæther in the late 1970s. The use of such arguments
> as true synapomorphies are problematic because it is difficult to
> positively identify the potential of a structure if it is not present.
> (unless you find the gene regulating the feature) . Thus, there has  
> been
> a lot of debate around the value of 'underlying synapomorphies' in
> phylogenetic analysis. Although I think this type of characters are
> problematic to use a priori, I agree with you that they could be  
> used a
> posteriori to explain certain character distributions on established
> phylogenies.
> Best regards,
> Torbjørn
> Dr. Torbjørn Ekrem
> Vitenskapsmuseet, NTNU
> Seksjon for naturhistorie
> 7491 Trondheim
> Museum of Natural History and Archaeology
> Norwegian University of Science and Technology
> NO-7491 Trondheim, Norway
> Tel: +47 73 59 78 12
> Email: Torbjorn.Ekrem at vm.ntnu.no
> Web: www.ntnu.no/~torbjoe
>> Sure, 'de novo' appearances might be possible for complex  
>> structures if
>> these are hidden in the genome and turned on holus bolus by some
>> regulatory gene. In other words, all the tools for making the  
>> structures
>> might be present but might not be consistently expressed in  
>> descendant
>> lineages. IMO this doesn't invalidate the Yellow intuition, it just
>> pushes the node of common ancestry further up the hierarchy.
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