[Taxacom] Paraphyletic groups as natural units of biological classification

[John Grehan]

Sorry, Its not Curtis but Steven for my response. Sorry, I hate gmail
formatting sometimes.

John Grehan

On Sat, Sep 27, 2014 at 9:52 AM, John Grehan <calabar.john at gmail.com> wrote:

> Curits said
>
>
>
> “Let's face it, a large proportion of the systematics/taxonomic community
> clings to monophyly like a baby to its mother's breast! It is so ingrained
> that it is probably impossible to shift.”
>
> Hmm. Maybe we could just as equally turn that around to say ““Let's face
> it, a large [large, small, I don’t know] proportion of the
> systematics/taxonomic community clings to paraphyly like a baby to its
> mother's breast! It is so ingrained that it is probably impossible to
> shift.”
>
>
> I say this to point out the absurdity of just labeling the ‘other side’ as
> somehow irrational. Everyone is in the same boat when it comes to science.
>
>
> If stability is the goal then it may be relatively easy to achieve. I can,
> for example, designate the group of ‘all things that have chlorophyll. Of
> course for any definition there will always be something to argue about.
>
>
> What is the objective criterion for recognizing that there are “too many
> monophyletic groups”
>
>
>
> John Grehan
>
> On Fri, Sep 26, 2014 at 6:31 PM, Stephen Thorpe <
> stephen_thorpe at yahoo.co.nz> wrote:
>
>> Ken (and list):
>> Let's face it, a large proportion of the systematics/taxonomic community
>> clings to monophyly like a baby to its mother's breast! It is so ingrained
>> that it is probably impossible to shift. As with everything, the idea of a
>> strictly monophyletic classification has its pros and cons. The main cons
>> seem to be (1) instability of classification, resulting from the fact that
>> determining monophyletic groups is evidence based science, subject both to
>> changes resulting from additional data, and from subjective differences in
>> the evaluation of evidence; and (2) one tends to be left with a
>> paraphyletic residue which is just too hard to crack. There are only two
>> options for forcing these residues to be monophyletic. Either (1) just
>> recognise the wider monophyletic group and don't recognise any of the
>> included monophyletic groups (e.g. recognise reptiles, but not birds); or
>> (2) split up the residue into trivially monophyletic groups (maybe down to
>> single species).
>>  The problem with (1) is obvious. The problem with (2) is that you end up
>> with far too many monotypic higher groups which don't really differ
>> diagnostically from each other except in as much as the species can be
>> distinguished. In my experience, scientists in our broad area are not so
>> good at weighing up pros and cons and coming to a sensible and rational
>> decision about what to do. They just cling to ideals ...
>> Stephen
>>
>> --------------------------------------------
>> On Fri, 26/9/14, Kenneth Kinman <kinman at hotmail.com> wrote:
>>
>>  Subject: [Taxacom] Paraphyletic groups as natural units of biological
>> classification
>>  To: "taxacom at mailman.nhm.ku.edu" <taxacom at mailman.nhm.ku.edu>
>>  Received: Friday, 26 September, 2014, 12:52 PM
>>
>>
>>
>>
>>  Dear All,
>>             I was just
>>  rereading a 2010 paper by Horandl and Stuessy (published in
>>  the journal Taxon).  It should be required reading in
>>  any systematics course.  Below is the abstract.
>>
>>      --------------------Ken
>>
>>
>>
>>
>>
>>  Hörandl, E. & Stuessy, T.F.  2010.
>>  Paraphyletic groups as natural units ofbiological
>>  classification.  Taxon 59: 1641-1653.
>>
>>  ABSTRACT:
>>  Despite the broad acceptance of phylogenetic principles in
>>  biologicalclassification, a fundamental question still
>>  exists on how to classifyparaphyletic groups. Much of the
>>  controversy appears due to (1) historicalshifts in
>>  terminology and definitions, (2) neglect of focusing on
>>  evolutionaryprocesses for understanding origins of natural
>>  taxa, (3) a narrow perspective ondimensions involved with
>>  reconstructing phylogeny, and (4) acceptance of lowerlevels
>>  of information content and practicability as a trade-off for
>>  ease ofarriving at formal classifications. Monophyly in
>>  evolutionary biology originallyhad a broader definition,
>>  that of describing a group with common ancestry.
>>  Thisdefinition thus includes both paraphyletic and
>>  monophyletic groups in the senseof Hennig. We advocate
>>  returning to a broader definition, supporting use
>>  ofAshlock's term holophyly as replacement for monophyly
>>  s.str. By reviewingprocesses involved in the production of
>>  phylogenetic patterns (budding, merging,and splitting), we
>>  demonstrate that paraphyly is a natural transitional stage
>>  inthe evolution of taxa, and that it occurs regularly along
>>  with holophyly.
>>  When a new holophyletic group arises, it usually coexists
>>  for some time with itsparaphyletic stem group. Paraphyly and
>>  holophyly, therefore, representrelational and temporal
>>  evolutionary stages. Paraphyletic groups exist at alllevels
>>  of diversification in all kingdoms of eukaryotes, and they
>>  havetraditionally been recognized because of their
>>  descent-based similarity. Wereview different methodological
>>  approaches for recognition of monophyleticgroups s.l. (i.e.,
>>  both holophyletic and paraphyletic), which are essential
>>  fordiscriminating from polyphyly that is unacceptable in
>>  classification. Forarriving at taxonomic decisions, natural
>>  processes, information content, andpracticability are
>>  essential criteria. We stress using shared descent as
>>  aprimary grouping principle, but also emphasize the
>>  importance of degrees ofdivergence plus similarity
>>  (cohesiveness of evolutionary features) as
>>  additionalcriteria for classification.
>>
>>
>>
>>
>>
>>
>>
>>  _______________________________________________
>>  Taxacom Mailing List
>>  Taxacom at mailman.nhm.ku.edu
>>  http://mailman.nhm.ku.edu/cgi-bin/mailman/listinfo/taxacom
>>  The Taxacom Archive back to 1992 may be searched at:
>> http://taxacom.markmail.org
>>
>>  Celebrating 27 years of Taxacom in 2014.
>>
>> _______________________________________________
>> Taxacom Mailing List
>> Taxacom at mailman.nhm.ku.edu
>> http://mailman.nhm.ku.edu/cgi-bin/mailman/listinfo/taxacom
>> The Taxacom Archive back to 1992 may be searched at:
>> http://taxacom.markmail.org
>>
>> Celebrating 27 years of Taxacom in 2014.
>>
>
>