Any non-aggressive folks interested in discussing taxonomy?

Discussion in 'Codex taxinomiae plantarum (CTP)' started by VAAlbert, Feb 17, 2009.

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  1. Feb 17, 2009 #1

    VAAlbert

    VAAlbert

    VAAlbert

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    Hi there:

    Any non-aggressive folks interested in discussing taxonomy?

    I've been away for a long time due to an extreme aggression aversion ...

    Best wishes,

    Vic Albert.
    (Prof., Univ. Buffalo, Mexipedium guy)

     
  2. Feb 17, 2009 #2

    kentuckiense

    kentuckiense

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    Sure. I can't think of any good starter topics, though.
     
  3. Feb 17, 2009 #3

    SlipperKing

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    count me in too.
     
  4. Feb 17, 2009 #4

    Ernie

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    I'm in!!! Get the ball rolling...

    -Ernie
     
  5. Feb 17, 2009 #5
    Yep, I am in...Just give us a topic...

    Oh here is one: Where do you draw the line of calling something a variety of a species, and when do you call something a "new" species? Say if someone finds one plant in a shipment of a species that he got in, and it clearly looks different, but yet you can tell it is related to a known species (This happened when Jerry Fischer, got some Phrag. schlimii plants from Ecuador, one plant within the shipment was very different, and was described by Guido Braem as Phrag. fischeri).

    My question is: when do you give something that is clearly distinct, but yet related to a known species a different variety name of that species, or when would you give it a "new" species name?

    I can think of many examples (Phrag. fischeri vs Phrag. schlimii, Phrag. dalessandroi vs Phrag. besseae, Phrag. exstaminodium vs. Phrag. popowii, Paph. viniferum vs Paph. callosum, Paph. hiepii and Paph jackii vs. Paph. malipoense, and the newest: Phragmipedium manzurii, should this be a separate species, or is it a variety of schlimii etc etc..)

    Robert
     
  6. Feb 17, 2009 #6

    Ron-NY

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    Robert,
    Good starter question!

    IMHO (for what ever that is worth) similarity of DNA or morphology is the factors that determine if something is the same species or not. Presence of specific locally adapted traits may further subdivide species into variety, subvariety, and form. This question on how best to define "species" is one that has occupied biologists for centuries. There has always been the "lumpers" and the "splitters". Traditionally, plants were placed into a different species based on observations of anatomical differences. Now, with the capability of DNA analysis, placing things into a distinct species should be easier but still not a perfect science.
     
  7. Feb 17, 2009 #7

    slippertalker

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    That's an interesting question which taxonomists even debate. As far as I can discern, it comes down to a matter of philosophy of relationships of plants rather than any prescribed laws of taxonomy. As Ron mentions, often it is a matter of lumping vs splitting or showing closely aligned species seperate or as subspecies.

    Science operates in an open ended manner and taxonomy follows this trend. There is always room for more information (DNA, field study, etc) in determining whether differences are just variation or a seperate entity. Lumping or splitting seems to be a parlor game that taxonomists use to amuse themselves and cause consternation from their colleagues, but is usually used in an honest manner as the facts evolve.
     
  8. Feb 17, 2009 #8

    nikv

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    I find these discussions to be fascinating, but I'm not a biologist or taxonomist, so I have nothing to offer. But I'll eagerly watch this discussion from the sidelines. :)
     
  9. Feb 17, 2009 #9

    VAAlbert

    VAAlbert

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    Well, for starters, I am definitely in favor of checking relationships of particular plant individuals at the DNA level. When I say individuals, I really do mean individual clones, since the extent of natural genetic variation within what looks 'the same' or similar could be rather low or rather high. Populations of plants are notorious in this aspect, and understanding individual variation within populations -- AND between them -- is very important in my view. In narrow endemics like most Paphs and Phrags, the situation of ALLOPATRY (geographically distinctness) often leads to both genetic and morphological divergence. Allopatric SPECIATION can occur if gene flow, e.g., is largely cut off between populations, leaving them to go their own way further still. This said, in plants, the definition of species is more clouded than simple lumping vs. splitting, because real reproductive isolation may not be enforced at all if 'species' come into contact. Although botanists have found many, many more examples of cryptic reproductive isolation through, e.g., partial fertility barriers than previously supposed, there are NOWHERE NEAR as many examples of gene flow between recognized species of animals -- vertebrates, say. Plants extend their promiscuousness by having the tendency to form polyploids along with hybridization events. Angiosperms go crazy with polyploidization, and it's surprising that so few natural slipper tetraploids have been identified. Polyploidy is a way out of any reproductive barrier between 'species' (or distinct populations of 'species') that might come into contact.

    Going on to the issue of when a new species, subspecies, or variety might be named, this does indeed involve quite a bit of hand waving. Some (like me) would like to see biodiversity given concrete description, and the best way to preserve the intent of describing biodiversity is at the species level, since species names NEVER DIE -- they can simply be ignored if one wants. So maybe it's A-OK to name a Phrag. dalessandroi and then have most of the world consider the plant Phrag. besseae var. or subspecies dalessandroi. I don't know which of the latter names have been validly published, or which are in most common use -- the fact remains that the Latin binomial Phrag. dalessandroi is always there as a formally described entity. Subsuming Phrag. dalessandroi into besseae is merely a decision you or I could make -- nobody can rid themselves of the existence of the name Phrag. dalessandroi since it was validly described. So use it if you like, or any other valid name that might apply to a given individual plant with features that fit.

    As for Phrag. schlimii vs. fischeri vs. manzurii, I guess I'd support their DESCRIPTION as species in order to get the Latin binomial on record. Of course, one could validly describe manzurii as a variety of schlimii -- accept what you want -- the same packages of biodiversity are there even if one less 'species' is on the Phrag. list.

    New species especially, but also new subspecies or hybrids, create a lot of excitement in the orchid world -- folks gotta have 'em. So, any new names create markets, no matter how small the morphological differences.

    Many examples of new species are dead clear -- like when Phrag. besseae or Paph. malipoense were discovered. But then the subtlties creeped in when natural variation led some to accept the species Phrag. dalessandroi and Phrag. jackii. Well, the latter two are different from the former 2, and do appear to form distinct populations, and are probably a little distinct at the DNA level. I'm glad that Phrag. dalessandroi and Paph. jackii exist as names recognizing diversity, but it just doesn't matter taxonomically if they are referred to as varieties. If one is interested in various aspects of evolutionary biology beyond taxonomy, such as population genetics, pollination interactions, or ecology, one might care more than I would.

    These are my 2 cents -- rambling a bit, sorry for that. And I may change my mind on some things I wrote!

    All best,

    Vic.

     
  10. Feb 17, 2009 #10

    NYEric

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    Is DNA review part of taxonomy?
     
  11. Feb 17, 2009 #11
    Here we go-

    Now if you wake up Lance Birk '
     
  12. Feb 17, 2009 #12

    VAAlbert

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    No, taxonomy need not include anything about DNA. It can come purely from morphological considerations. Sometimes DNA can be helpful in decisions, however, as I already alluded to.

    For the record:

    Nomenclature = the process and act of erecting names through a set of rules recognized for all plants

    Taxonomy = the practice of creating a classification from validly published names

    So, nomeclaturally speaking, Paph. jackii exists, and so does Paph. malipoense var. jackii. Taxonomically speaking, taxonomist A can recognize the species, and B the variety, while referring to exactly the same plant specimen! Classifications exist in flux, though we would like to try to keep them stable. Synonymizing one species under another doesn't change the nomenclatural fact that the first name will persist. So Phrag dallesandroi will always exist, even if taxonomist B never lists it, or even Phrag. besseae var. dallesandroi. So long as the species names are validly published...
     
  13. Feb 17, 2009 #13

    NYEric

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    That's what I thought. Unfortunately, this makes it subjective when someone decides that a plant 'looks' different enough from another to be described as a different variety or species.
     
  14. Feb 17, 2009 #14

    VAAlbert

    VAAlbert

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    True enough, there is this subjectivity. But decisions can be more or less informed. Very careful morphological, ecological, and other examinations, not to mention DNA work, can make for better descriptive work
     
  15. Feb 17, 2009 #15

    NYEric

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    Then DNA work should be required as that's the only examination that's not transferable. Unfortunately, there may be only one plant to sample. :(
     
  16. Feb 17, 2009 #16

    slippertalker

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    DNA studies have only confused the data depending on the focus. For good examples of rushing to judgement based on DNA, look at the recent myriad of changes with the Cattleya alliance and also the recent inclusion of Odontoglossum into Oncidium. There is no doubt that these are closely aligned species but basing them on DNA versus morphology which is traditional has cause much consternation. One would hope for clarification, but instead it has muddied the waters.
     
  17. Feb 17, 2009 #17

    NYEric

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    You prefer lumping, it's easier but not accurate. I don't like all the changes but it aided in separating the pleurothallids which were lumped together even though they are anatomically now distinct.
     
  18. Feb 17, 2009 #18

    VAAlbert

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    Again, DNA can only be one factor --

    Still, I believe in the principle of monophyletic classification -- genera should only be recognized if they have unique origins on phylogenetic trees; if they originate in many places, genera need renaming. Sometimes trees show large genera contain some smaller ones; then the large genera are non-monophyletic, and new classification is required to recognize only monophyletic genera. Remember, proper nomenclature must be available or made to make transfers of species or to erect new genera.

    Monophyly is important to me because it is an evolutionarily sound principle, and because it leads to the most predictive classifications when/if new species are discovered. In other words, monophyletic genera can be defined by suites of unique characters, instead of sets of characters that must exclude some others. My 3 cents.

    BW,

    Vic.
     
  19. Feb 17, 2009 #19
    Just a clarification, DNA analysis has nothing to do with taxonomy but with systematics and phylogenia... in systematics teh relationship between species (or other groups) is studied and DNA provided a bir support to it. Taxonomy is a more traditional science based mainly on morphological characters... even though, it has some limitations, like using the correct markers, etc...

    now, where to put the limits between species, sub-species, variety and so on... it depends ONLY on the taxonomist making the description!

    a last note: as for my understanding the newest "re-unification" of Odontoglossum and Oncidium (and many other genera) was based not on DNA analysis... I have read it was made based on pollinators (need to confirm this, because even though I read it on a source I normally trust, this sounds so ridiculous that I can hardly believe its true!)
     
  20. Feb 17, 2009 #20

    VAAlbert

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    No, DNA does have to do with phylogenetics, and can inform taxonomy. Systematics is a word that has come to mean different things to different people, sometimes either phylogenetics or taxonomy, or even both.

    Again, taxonomy can use DNA evidence (= phylogenetics, population genetics) to help support classifications (= taxonomies).

    Quite so! So long as validly published names are used within the valid taxonomic hierarchy.

    Don't know about this -- I am totally slipper-interested!

    Best,

    Vic.
     

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