[Taxacom] LOL (was Re: New lizard species)

[Stephen Thorpe]

>> If speciation is largely a paraphyletic process, which it might be, 
>> then where does that leave cladograms (=sister-group diagrams)??
> Paraphyletic species don't necessitate paraphyletic higher taxa.


I possibly should have said 'if evolution (?=cladogenesis) is largely a paraphyletic process, ...'

My thought is this:

just as an example, suppose that all amniotes evolved from just one population of "ordinary" (not basal)  frogs, by rapid character change (perhaps the result of a small isolated population being subjected to relatively high levels of nuclear radiation from a natural source, followed by a geological event which opened up a dispersal route to a vast continent) , and diversified into the amniotes as we know them, while the other frogs all just evolved very slowly and diversified only into the rather similar creatures that we are familar with. It COULD have happened that way in theory, but where would that leave biological classification from a cladistic perspective? All the amniotes would be cladistically within a genus of ordinary looking frog! Formally, one could in that situation split the frogs up into various clades of equal rank to Amniota, but there would be so few nontrivial morphological/diagnostic characters to separate them that it
 would be absurd ...

this imaginary example is extreme, but a less extreme form of it may in fact be commonplace. There appear to be many distinct clades with "paraphyletic remainders" (i.e., like the Amniota and frogs, respectively, in the above example) ...

Stephen


________________________________
From: Curtis Clark <lists at curtisclark.org>
To: taxacom at mailman.nhm.ku.edu
Sent: Fri, 11 June, 2010 2:03:52 PM
Subject: Re: [Taxacom] LOL (was Re: New lizard species)

On 6/10/2010 4:04 PM, Stephen Thorpe wrote:
> If speciation is largely a paraphyletic process, which it might be, 
> then where does that leave cladograms (=sister-group diagrams)??
Paraphyletic species don't necessitate paraphyletic higher taxa.

-- 
Curtis Clark                  http://www.csupomona.edu/~jcclark/
Director, I&IT Web Development                  +1 909 979 6371
University Web Coordinator, Cal Poly Pomona


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