Darwin (was: Phylogenetic evidence)
peter.stevens at MOBOT.ORG
Thu Jul 11 13:31:18 CDT 2002
Those interested in Darwin and classification might want to read
Kevin Padian, "Charles darwin's views on classification in theory and
practice". Syst. Bio. 48: 352-364. 1999.
As to what CD would think if he were alive today, I will consult my
medium. If it is printable, I will let you know.
> I detect no hint of any complaint (about ranks) in Darwin's statement.
> Could this be wishful thinking on your part? :-)
> Seems to me he is making a straightforward observation about how to
>"express" differential anagenesis (different degrees of modification) in a
>classification. And this can be just as true for molecular data as it is
>for morphological data.
> It's perfectly natural to give two sister groups different rank based
>on different degree of divergence. The therapsid Family Tritheledontidae
>went extinct early on and therefore had no chance to diverge nearly as far
>as its sister group Class Mammalia. Likewise a genus can be a sister group
>to a whole family or even an order. I see no problem with this as long as
>you explicitly show such sister group relationships (as I do with my exgroup
> Seems to me Darwin is just acknowledging that this is the way it was
>done and there would have been no need to "endorse" it. And this is still
>done, in spite of strict cladism's efforts to demonize and snuff out
>paraphyly completely. If you really think Darwin was a proponent of
>unranked taxonomy, I would think you could find a more direct statement in
>his many writings. I don't recall any indication that he would have
>preferred unranked classifications, nor do I have any reason to believe he
>would prefer strict cladism if he were alive today.
> ------ Cheers, Ken
>>From: Barry Roth <barry_roth at YAHOO.COM>
>>Reply-To: Barry Roth <barry_roth at YAHOO.COM>
>>To: TAXACOM at USOBI.ORG
>>Subject: Re: Phylogenetic evidence
>>Date: Wed, 10 Jul 2002 09:03:14 -0700
>>They say the Devil can cite scripture for his purposes. Let's see. In
>>your linked message you quote Darwin thus:
>> "but that the amount of difference in the several branches or
>>though allied in the same degree in blood to their common progenitor, may
>>differ greatly, being due to the different degrees of modification which
>>they have undergone; and this is expressed by the forms being ranked under
>>different genera, families, sections, or orders." (Origins of Species,
>>I read this as Darwin's insight that morphology is an imprecise guide to
>>degree of consanguinity and his recognition that the standard, ranked
>>classification is based on "magnitude of difference" in morphology, not
>>phylogeny. He states that this is the case; he doesn't necessarily endorse
>>it. In fact, his statement is a complaint about the problem.
>>I therefore claim Darwin as an early proponent of unranked taxonomy.
>>BR (adjusting his horns)
>> Ken Kinman wrote:Barry,
>>I wholeheartedly agree with Darwin on this, but this is only a partial
>>quote, and omits an extremely important qualifier (which strict cladists
>>often prefer to ignore).
>>See my post on this subject in January 2001 at the DML (dinosaur
>>mailing list). Here's the link:
>>Do You Yahoo!?
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