fossils as roots

[Thomas Schlemmermeyer]

To the problem of rooting: While I assisted a podium discussion
on the last brazilian congress of zoology in Recife, one nice
brazilian scientist with hawaiian experience (I think, Claudia Russo
was hear name, but I cannot swear that!) said that the future of systematics
will be without monophyletic groups and roots at all!!!

Of course, she earnt only laughter and disagreement by the other, by the way,
exclusively male participants.

But everytime, when I use some public transportation system, like a metro,
where they have these unrooted networks to show the connections between the
stations, I wonder whether science really will have to work with roots of
phylogenies forever or whether on some point in the future this concept
will be abandoned, as well.

       Thomas




On (    Fri, 5 Mar 1999 07:10:02 PST), Ken Kinman <kinman at hotmail.com> wrote:


>     Using fossils as an informative root depends mostly on what group
>of organisms are being analyzed, and the quality and quantity of it's
>known fossil record.  There is probably a whole continuum of fossil
>"usefulness", from (1) virtually worthless (bacteria for instance, where
>genetic data are the most useful characters) to (2) crucial (the
>mammalian fossil record is extremely important to our understanding of
>that group's evolution).  And between such extremes, fossil information
>can be more or less useful depending on what characters are being used
>and how well they show up in the fossil record.
>     Rooting in cladistic analysis can be a tricky business, especially
>when it comes to fossils.  Even when one is dealing only with extant
>forms, misrooting can have grave consequences, and Carl Woese's
>misrooting of the tree of life (once it is fully exposed) will become a
>prime example of how such misrootings can lead one to false conclusions.
>But that story is still unfolding and mired in debate.  Probably the
>most important lesson to be learned from it, will be that one should try
>experimenting with a number of different rootings before becoming too
>attached to any one in particular, whether they are fossil or extant.
>                              Sincerely, Ken Kinman
>********************************************************
>>Date:         Wed, 3 Mar 1999 07:38:36 -0700
>>Reply-To:     Hilary Davis <davish at HOLLY.COLOSTATE.EDU>
>>From:         Hilary Davis <davish at HOLLY.COLOSTATE.EDU>
>>Subject:      fossils as roots
>>To:           Multiple recipients of list TAXACOM
><TAXACOM at cmsa.Berkeley.EDU>
>>
>>I'd like to hear some opinions on the use of fossils to root a
>cladogram
>>or tree.  Is this a valid technique given the possibility that a fossil
>>assemblage for a particular extant group may not be complete?
>>
>>Thanks,
>>Hilary Davis
>>Colorado State University
>>Department of Biology
>>davish at holly.colostate.edu
>
>______________________________________________________
>Get Your Private, Free Email at http://www.hotmail.com
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Thomas Schlemmermeyer
Museu de Zoologia, Universidade de Sco Paulo
Caixa Postal 42694
CEP 04299-970
Sco Paulo, SP, Brasil

Residjncia:
Thomas Schlemmermeyer
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CEP 14001-970
Ribeirco Preto, SP, Brasil

Fone, Fax: 016 6371999
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