[Taxacom] Paraphyletic groups as natural units of biological classification

Sun Sep 28 09:06:58 CDT 2014

One may certainly have a classification of convenience or one can have a
classification tied to phylogeny. Or one can use both with the caveat that
a paraphyletic grouping is deliberately leaving out some descendants.

John Grehan

On Sun, Sep 28, 2014 at 9:42 AM, Weakley, Alan <weakley at bio.unc.edu> wrote:

> Paul -- clearly I was writing that too late in the evening.  The
> ”gymnosperms" should of course be there between 2 and 3 in "classification
> 1" and between 7 and 8 in "classification 2".  And my class of 50 students
> better get that right on their midterm exam next week.  ;-)
>
> Gymnosperms of course offer their own set of problems in regard monophyly
> and paraphyly, in that extant gymnosperms may be a monophyletic group, and
> extant+extinct "gymnosperms" almost certainly a complicated paraphyletic
> grade with a branching order for which we may never have a strong
> hypothesis.  So, we can have one classification for "modern plant people"
> and several others (differing from the "modern" one) and from each other...
>
>
> -----Original Message-----
> From: Taxacom [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of
> Paul van Rijckevorsel
> Sent: Sunday, September 28, 2014 6:59 AM
> To: taxacom at mailman.nhm.ku.edu
> Subject: Re: [Taxacom] Paraphyletic groups as natural units of biological
> classification
>
> In my book the Gymnosperms are still vascular plants.
> Whatever happened to them?
>
> Paul
>
> ----- Original Message -----
> From: "Weakley, Alan" <weakley at bio.unc.edu>
> To: "Weakley, Alan" <weakley at bio.unc.edu>; "Curtis Clark"
> <lists at curtisclark.org>; <taxacom at mailman.nhm.ku.edu>
> Sent: Sunday, September 28, 2014 6:08 AM
> Subject: Re: [Taxacom] Paraphyletic groups as natural units of biological
> classification
>
>
> > Put another way.
> >
> > And see:  http://www.mobot.org/MOBOT/research/APweb/
> >
> > If, in vascular plants, one wanted to create a broad set of groups
> > useful for classification, teaching, recognition, etc., one might want
> > to
> > recognize:
> >
> > 1.  Lycophytes
> > 2.  Ferns
> > 3.  "Basal angiosperms"
> > 4.  Monocots
> > 5.  "Basal Eudicots"
> > 6.  Rosids s.l.
> > 7.  Asterids s.l.
> >
> > Each of these is diagnosable morphologically, and each has a clear
> > evolutionary position relative to the others.  But 3 and 5 are not
> > monophyletic, they are grades (as based on current phylogenetic
> > reconstructions):  3 a grade relative to clade 4+5+6+7, and 5 a grade
> > relative to clade 6+7.  Making the entities in grade 3 separate
> > monophyletic units makes an additional 3 or more units.  Making the
> > entities in grade 5  separate monophyletic entities makes 5-6 (or
> > more) additional units.  1 is monophyletic, but includes very ancient
> > (Devonian) (and morphologically easily distinguishable) entities.
> >
> > So, with good basis and with (only a little) less angiosperm bias, one
> > could easily substitute for 1-7 above, and with strict monophyly:
> >
> > 1.  Huperziaceae
> > 2.  Lycopodiceae
> > 3.  Equisetaceae
> > 4.  Psilotaceae
> > 5.  Ophioglossaceae
> > 6.  Horsetails
> > 7.  Ferns
> > 8.  Amborella trichopoda (1 species)
> > 9.  Nymphaeaceae
> > 10.  Austrobaileyales
> > 11.  Magnoliales
> > 12.  Monocots
> > 13.  Ceratophyllum (6 species)
> > 14.  Ranunculales
> > 15.  Proteales
> > 16.  Trochodendrales
> > 17.  Buxales
> > 18.  Gunnerales
> > 19.  Dilleniaceae
> > 20.  "Rosids"
> > 21.  Santalales
> > 22.  Berberidopsidales
> > 23.  Caryophyllales
> > 24.  Cornales
> > 25.  Ericales
> > 26.  "Asterids"
> >
> > Note that while each of 1-7 are monophyletic, each contains divisions
> > (not
> > shown) that are older and "more fundamental" than any of those in 9-26.
> >
> >
> >
> >
> >
> >
> >
> > -----Original Message-----
> > From: Taxacom [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of
> > Weakley, Alan
> > Sent: Saturday, September 27, 2014 11:09 PM
> > To: Curtis Clark; taxacom at mailman.nhm.ku.edu
> > Subject: Re: [Taxacom] Paraphyletic groups as natural units of
> > biological classification
> >
> > Here seems to be "the thing".
> >
> > The "basal angiosperms" or "primitive dicots" or "ANITA and the
> > Magnoliids" or...  are clearly a basal grade to other angiosperms,
> > based on all recent analyses.  Amborellales sister to all other
> angiosperms.
> > Then Nymphaeales sister to all the rest, then...  ETC.  Whether you
> > have access to all the papers, a good summary of the current consensus
> > can be had online at the Angiosperm Phylogeny Website, at MoBot,
> > compiled by Peter Stevens.  This clearly shows a grade of various
> > orders (all small,
> > currently) and then also the magnoliids (mostly small, currently,
> > except especially, the Lauraceae and somewhat less so the Piperaceae).
> >
> > So, the "basal angiosperms" are not monophyletic.  And yet, it is
> "useful"
> > and "convenient" to refer to them as a group -- to classify them as a
> > unit.  In teaching, and in floras (Flora of Virginia 2012, Flora of
> > the Southern and Mid-Atlantic States 2014)), it is "handy" ("useful")
> > to divide the vascular flora into:  Lycophytes, Ferns, Basal
> > Angiosperms, Monocots, and Eudicots.  It seems "disproportionate" to
> > treat 4 or more units (small, currently, a genus or two, a hundred
> > species or less, each) at equivalent rank to Monocots or Eudicots,
> > which have many more orders, families, genera, and species.
> > Especially, as their morphological differences seem relatively
> > obscure, abstruse, and non-obvious.  If the morphological distinctions
> > were completely obvious, maybe we would be more accepting -- no-one
> > seems to have a hard time with Ginkgo or Welwitschia as (modern)
> monotypes:  uncontroversial monotypic orders.
> >
> > So, Judd et al., for instance, in their textbook, Plant Taxonomy: a
> > Phylogenetic Approach, use quotes to indicate units that are not
> > monophyletic but yet are "useful".  There is an interesting tension
> > here between "strict monophyly" and "intuitive (useful) classification
> units".
> > Units with quotes seem to flag something like "this is not
> > monophyletic but sure is handy so we will keep using it informally".
> >
> > I'm not taking sides here (I am conflicted).  But...  it may be
> > instructive to contemplate that other "intuitive (useful)
> > classification units" ("plants", "animals", "algae", "fungi", "birds",
> > "bacteria", "slime-molds", ) have fared increasingly poorly over time
> > as real classification units.  I was taught as a college botany
> > student in the 1970s that there were 2 main types of algae (a kind of
> plant):
> > prokaryotic ("blue-green algae") and eukaryotic (green, red, brown,
> > etc.,
> > algae) --  several decades on, this looks laughable (and in no way
> > "useful" or "convenient" in any respect).  On the other hand, the
> > "Basal Angiosperms" seem a "useful" unit for teaching and organization
> > and classification, even if monophyly is uncertain or even disproved...
> >
> > -----Original Message-----
> > From: Taxacom [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of
> > Curtis Clark
> > Sent: Saturday, September 27, 2014 9:29 PM
> > To: taxacom at mailman.nhm.ku.edu
> > Subject: Re: [Taxacom] Paraphyletic groups as natural units of
> > biological classification
> >
> > On 2014-09-27 6:59 AM, John Grehan wrote:
> >> Since you have some expertise and strong opinions on paraphyly I
> >> presume you have read the citation of Stuessy (2010) on basal
> >> angiosperms being a paraphyletic group. As I do not have immediate
> >> access to that paper perhaps you could describe in what way that
> >> group was paraphyletic.
> >
> > Some of its members (Austrobaileyaceae?) are more closely related to
> > the rest of the angiosperms than others are. (Same definition as
> > usual.)
> >
> > --
> > Curtis Clark        http://www.csupomona.edu/~jcclark
> > Biological Sciences                   +1 909 869 4140
> > Cal Poly Pomona, Pomona CA 91768
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> Celebrating 27 years of Taxacom in 2014.
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