Split vs. Lump?

Discussion in 'Taxonomy' started by Heather, Aug 29, 2006.

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  1. Aug 30, 2006 #21

    PHRAG

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    Jon, I have been looking at dozens of photos of philippinense trying to spot differences between the three types. Can someone please clarify what the difference is between the plants above? To my eyes, they look like three of the same exact species with just normal growth variations. Educate me, please.
     
  2. Aug 30, 2006 #22

    Jon in SW Ohio

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    That is almost exactly what defines a splitter vs. a lumper. If you can't see the difference, you're a lumper; if you easily can, you're a splitter.

    To me, the three plants above are different as night and day. Pick any of the three at random and show me it in bloom or out, and I will know without guessing which is which instantly every time. Are these differences something tangible that I can write a definite key to identify? Not really, the differences are extremely minor.
    The keys I've read to differentiate them don't necessarily correspond either. I personally have never seen a roebellenii without green veining on the staminode which is supposed to be one of the key identifing characteristics from the original description.

    As said before, I'm a splitting lumper (or lumping splitter). I see diffrences, but prefer the use of formas and varieties instead of species. I personally don't see the big difference between besseae and d'allesandoi...they are both small red micropetalum phrags! But, do I think they should be differentiated somehow? ABSOLUTELY! That is why my tag says Phrag. besseae var. d'allesandroi. If it isn't a very clear and consise difference like say besseae and schlimii, I don't like to use different species names.

    Jon
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    Last edited: Mar 15, 2011
  3. Aug 30, 2006 #23

    Heather

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    Well, I guess I'm just going to have to come to terms with being a splitting lumper (or vice versa) as I feel pretty much exactly the way Jon does about some of these.

    re: the philippinense group. It is subtle, but I also think I could make a good guess as to which was which between the three if shown plants out of bloom. Actually the roebelinii vs. philippinense blooms I find harder to distinguish than the plants on many occasions. P. laevigatum though, it's just a different fish altogether in my opinion.
     
  4. Aug 30, 2006 #24
    When my oldest son was in college, he did a research project for Dr. Ken Cameron, analysing DNA of several strap-leafed species...I donated leaves from "sanderianum", roth, philipinense and stonei....he had to send abroad for samples of genuine sanderianum (thanks to Simon Wellinga)...the results were interesting to me....as I expected, my "sanderianum" was not what it was labelled...most likely P of E...as nearly all sand's were at the time I got the seedling...but interestingly, my "roth" turned out not to be a straight species either...in fact, I think only philipinense was clearly what it was supposed to be ...and that was the only one of the group that originated as a collected plant way back when (I believe...). Overall, though, this type of DNA research focuses on only a few genes....and I could see how this would not be usefull in distinguishing closely related species. Overall, in terms of splitting and lumping, for the most part, we are looking at these plants horticulturally, not scientifically...so I am willing to accept that P. hirsutissimum and esquirolei may be conspecific, on a scientific level, but in my collection, they would be separate ...speaking of which, whatever happened to straight hirsutissimum? All that seems to be around now is esquirolei...and it is far more difficult to grow and bloom than the ordinary hirs., which I miss greatly......Take care, Eric
     
  5. Aug 30, 2006 #25

    silence882

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    For the phillipense/roebelenii/laevigatum issue, what definitions are everyone working off of? What makes a laevigatum different from a philippinense or a roebelenii? And what is the source of these definitions?

    I've gotten a few plants so far that have bloomed out other than what their tag says (as I'm sure everyone has). One of these was a Paph. glaucophyllum from Oak Hill that turned out to be an infra-sectional hybrid. However, at the time it bloomed I posted a pic on SOF as 'Paph. glaucophyllum' because that's what the tag said. I must admit, I was inadvertantly helping contribute to the confusion over the correct identity of the name.

    Another plant I bought was a Paph. gardineri. Oak Hill offered it as a good paph. species and I was new to orchids. It bloomed as a typical wilhelminiae. The description of Cyp. gardineri is a poor-quality line drawing of a bloom of the glanduliferum / praestans / wilhelminiae complex. There's no reason that the name gardineri should still be in use in botany or horticulture. However, vendors want more 'species' to sell, so there it is. Like laevigatum, the definition of gardineri has been informally created in horticulture, but no one is quite sure what it means because there are (as far as I know) no reliable written descriptions.

    I totally agree with this. New species arise when climactic/geologic changes occur leading to geographic separation of populations. Another good example of this is the species of Subgenus Cochlopetalum. Fowlie (in an OD article from the early 80's, I forget which exactly) proposed that all the sequential multifloral species descended from a single ancestor which was limestone-dependent. Sumatra and Java used to be primarily limestone, but over time molten lava turning to rock from the gap between tectonic plates which the islands sit on gradually raised the islands. As the limestone layers rose in elevation, the rains they were subjected to became cooler, causing them to erode more quickly. As a result, the limestone that remains on Sumatra and Java is in scattered outcrops. The once widespread common ancestor was now relegated to the limestone outcrops that remained and distinct, geographically isolated populations formed. Over time, these populations changed enough to be considered unique species (by most).

    (Although, one species adapted to exist on volcanic rock, P. victoria-mariae)

    --Stephen
     
  6. Aug 31, 2006 #26

    SlipperFan

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    Poof! There goes my dream....
     
  7. Aug 31, 2006 #27

    Heather

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    Okay, that's just fascinating! Thank you....great discussion.
     
  8. Sep 1, 2006 #28

    myxodex

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    What a great discussion ... nothing quite like a can of worms to get one's teeth into. Can't resist .. here are my thoughts.

    As hobbyists or horticulturists we are concerned about visual differences and want to be able to label them. So am I a splitter? I think it depends on the context and the application. Drorchid raised some very important points. In the wild species exist as populations ... for some folk species are simply isolated genetic pools and the genetic variance within them is determined by enviromental factors and selection pressure. From an evolutionary point of view species survival depends in the long run on this genetic variability. So when it comes to the situation that we want to re-introduce a species to the wild, to my mind it would be folly to select only our favourite cultivar ... we need to replace a population with some genetic variability. The question is then do we have this genetic variability in cultivation for rare species? If we do not wish to introduce hybrids into the wild then we need to know where species boundaries are by definition. But then the species definitions are in some sense artificial, imposed and always changing ... yesterday a hybrid tomorrow not! Phew! what a mess! I think I'm a lumper-splitter hybrid!

    As for the DNA sequencing approach I'm not 100% pessimistic (only 99%), but we are far, ... very far from having the capacity to do this properly. We would need to gather the complete genomic sequence of thousands of wild plants ... find the most informative regions (hugely problematic) ... use a variety of clustering methods to find natural groupings. If the different methods agree (big if) then you have a map which would tell you the genomic boundaries of a species. Each sample or individual sequence would be a prototype but also belong to a group. Cultivated hybrids we hope would fall into the gaps of this map and show only weak matching to any of the parental species prototypes ... so goes the dream. Financially impossible! However, using selected DNA sequences as has been done so far doesn't give totally wacky results, but needs a lot of improving. Perhaps there is a useful compromise. It is very early days in the field of molecular phylogeny ... we probably shouldn't throw the baby out of the window just yet!

    In the meantime I'll just enjoy my orchids, species and hybrids alike.
    Cheers,
    Tim
     
  9. Sep 1, 2006 #29

    Jon in SW Ohio

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    As of right now, I truely hate the genetic approach. This is because of one thing and it makes me scowl at the mere thought of it.

    Sophronitis.

    That's right. The easiest, most clearly defined genus in the whole world, and they had to screw it up based on genetic findings. I'm not going to go into species differences, which is a true splitter/lumper debate on it's own and this isn't the Cattleya Forum.
    What I'm talking about is grouping Laelias that look more like Cattleyas into the genus Sophronitis! I don't care what genetics say, if it is not small and red (or yellow on expensive ones) it is NOT a Sophronitis and I will NEVER label it as such. Sophronitis purpurata....*scowl*

    Rant over.

    Jon
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    Last edited: Mar 15, 2011
  10. Nov 26, 2006 #30

    VAAlbert

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    Really, the technology is here; the principal problem is focusing in on the right questions. Finances aren't really a huge problem either. A major reason for current pessimism is that DNA sequencing is not as informative among closely related plants as we'd like. What will be much better are what are called 'coding simple sequence repeats' (SSRs, EST-SSRs), which I and others use frequently with groups that you can't even get a phylogenetic tree from. The idea here is not to link all plant individuals by an unambiguous phylogeny, but to gain population-level insight into their evolutionary background. You need to make 1-3 large investments (maybe $15,000 each?) plus what's required to continue lab costs. Still, no approach is foolproof, but this is the way I'd go with slippers at this point if I were still working on them.

    Best wishes,

    Vic Albert
     
  11. Nov 26, 2006 #31

    Rick

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    Wow Victor.

    Haven't heard from you in a while. Good to hear from you again.:clap:
     
  12. Nov 27, 2006 #32

    VAAlbert

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    Thanks, Rick.

    I still grow them, but haven't done research on them for a very long time. I've thought about trying a few things, however. For example, the Mexipedium story isn't finished, so far as I'm concerned. The support for Mexipedium as the sister group of Phragmipedium vs. sister to Paphiopedilum, vs. sister to both (!), isn't really there in the published data. The published tree from DNA sequences is not the only tree one can get from the data; it depends on how the sequences are aligned.

    Regards,

    Vic.
     
  13. Nov 27, 2006 #33

    NYEric

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    I like Heather's original post and would prefer splitting. The issue is really created when species are intermingled in the wild. I'm not going say one is better than the other, rather it would be great to know which hybrid is really what it's ancestry tells us it is.
     
  14. Nov 27, 2006 #34

    slippertalker

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    In the end, what difference does it make whether the species are lumped or split? As long as we understand what label is on which species, I don't care whether it is labeled as a species or a variety of a species. Looking at several of the above postings, it's clear that there are many mis-labeled plants, and hybrids named as species which causes even more confusion.
     
  15. Nov 27, 2006 #35

    VAAlbert

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    Well,

    Species are for the most part artificial constructs, usually based on the opinion of a taxonomist. Don't confuse taxonomy with nomenclature - taxonomy is a classification - a system, whereas nomenclature encompasses the study of validly and invalidly published names used in classifications. Non-objective classifications involve 'hand waving'. That is, taxonomists working purely at the alpha level who do not try to subject characteristics (e.g., morphological, molecular, karyotypic) to objective phylogenetic reconstruction make non-objective taxonomies. Of course, choice of characteristics can be non-objective as well, but minimizing unnecessary assumptions (Ockham's razor) will always be more powerful than utilizing more.

    So, where does this leave one with lumping vs. splitting? Well, I'd first want to make sure I'm using the most objectively derived classification. I'll put in a vote for *basically* phylogenetic ones based on a particular body of data and a repeatable algorithmic procedure (did some of this myself). Then I'd make sure that I was following the rules of nomenclature for proper use of names in my classification. Of course, one must also bear in mind that a particular collection of data may not be entirely representative of the names chosen to represent that data! As has been pointed out, population-level variation can be significant, and the actual status of all slipper orchid gene flow will likely not be determined in reasonable time.

    So, a classification winds up with a taxonomist encompassing a certain amount of variation into what he/she calls a species. That amount of variation is non-objective, and will not be revealed by standard phylogenetic methods. No use even thinking about it. So ----- names on plants, in my opinion, should follow as an objective look at evolutionary history as possible, then take the species level with a grain of salt where variation is great. Paph. armeniacum and micranthum, e.g., pose no problems -- but lots of Lorifolia Phrags do, hence the difference in what taxonomists argue about.

    Nomenclaturalists will go about the task of validating names, describing new taxa, etc., and this is basically bookkeeping ---- not biology, and the endeavor does NOT result in better species concepts. Remember the difference between taxonomy (systems) and nomenclature (assigning names to be used in systems). The best species concepts, in my opinion, are (again) those that require the fewest number of excess assumptions to maintain them. So, one may need to lump sometimes in order to retain economy of assumptions, and split other times -- all based on whatever evidence is at hand -- and I believe that evidence should be made available in a form such that other persons can repeatably arrive at conclusions as often as possible. I co-described Mexipedium so that Phrag and Paph could be better held apart based on morphological evidence; this was based on both DNA and morphological data. I later sunk Mex and Phrag into Paph as an alternative, should others view the characters I used to separate Mex, Paph, and Phrag inadequate. Both classifications recognize the same organismal groups - only the hierarchical levels of the names are different.

    So, like my Mex example, I say let the taxonomists and nomenclaturalists not take themselves and their experience too seriously! If you like, Mex can still be a Phrag, but then my *opinion* is that you lose key characters for identification -- though you lose *nothing* in terms of a tracing of evolutionary history.

    If non-objective techniques for obtaining data were not available today for mammalogy, to give an example, standard taxonomy would probably not include a group that includes hippos and whales.

    Best wishes,

    Vic
     

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