[Taxacom] Paraphyletic groups as natural units of biological classification

Stephen Thorpe stephen_thorpe at yahoo.co.nz
Thu Oct 2 23:41:35 CDT 2014


Yes Curtis, I know what the word 'plesiomorphic' means. I do not understand your last sentence: Any time a species forms, it leaves behind a paraphyletic residue of whatever monophyletic group you choose.
Cheers,
Stephen

--------------------------------------------
On Fri, 3/10/14, Curtis Clark <lists at curtisclark.org> wrote:

 Subject: Re: [Taxacom] Paraphyletic groups as natural units of biological classification
 To: "taxacom at mailman.nhm.ku.edu" <taxacom at mailman.nhm.ku.edu>
 Received: Friday, 3 October, 2014, 4:36 PM
 
 On 2014-10-01 11:09 PM,
 Stephen Thorpe wrote:
 > That was uncalled
 for! I was trying to articulate an idea. If my terminology
 wuz in some way inappropriate, I apologise, but it was
 entirely unintentional.
 
 Sorry, but "plesiomorphic species"
 rubs me the wrong way. Characters (or 
 more
 precisely character states) are plesiomorphic.
 
 > Let me rephrase it in the
 form of a question: do you think it is common (or even
 possible) for a monophyletic group (M) to evolve quickly
 (within a larger monophylum), leaving only a remainder of
 plesiomorphic species which are very similar to each other,
 but very different to M?
 
 This is not an issue of science, but of
 terminology. Since monophyletic 
 groups are
 monophyletic, they have a single ancestral species, so
 we're 
 talking about speciation when
 that species splits from whatever. The 
 residue of species in the (now paraphyletic)
 group made by the exclusion 
 of your
 monophyletic group will of course have similarities that the
 
 monophyletic group doesn't share. They
 are called plesiomorphies; that's 
 what
 the word means. Any time a species forms, it leaves behind a
 
 paraphyletic residue of whatever
 monophyletic group you choose.
 
 -- 
 Curtis Clark        http://www.csupomona.edu/~jcclark
 Biological Sciences               
    +1 909 869 4140
 Cal Poly
 Pomona, Pomona CA 91768
 
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