[Taxacom] Paraphyletic groups as natural units of biological classification
Weakley, Alan
weakley at bio.unc.edu
Sun Sep 28 08:42:11 CDT 2014
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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