[Taxacom] ranked taxa

[Dr. David Campbell]

> Cladistics isn't the bad guy.  Strict representation of holophyletic
> clades
> via Linnean nomenclature is the bad guy.

Having some sort of ranks in the classification serves two valuable 
functions:

It helps in communicating the approximate level and inclusiveness of 
the taxon within the tree of life.  A new phylum is more exciting than 
a new species when you're browsing papers to read, for example.

It prevents later discovery of polyphyly or other change from 
dramatically altering the meaning of a name.  For example, Linnaeus' 
Nautilus included not only shelled cephalopods but also snails with 
partitions and foraminifera.  Define Nautius as the least inclusive 
clade including all originally included taxa, and it's close to a 
synonym of Eukarya.  Define it as a genus centered on the extant 
externally shelled cephalopods, and you have the traditional concept of 
Nautilus.  

-- 
Dr. David Campbell
425 Scientific Collections Building
Department of Biological Sciences
Biodiversity and Systematics
University of Alabama, Box 870345
Tuscaloosa AL 35487-0345  USA