Geographic distribution - usefullness?

Discussion in 'Codex taxinomiae plantarum (CTP)' started by silence882, Nov 29, 2006.

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  1. Nov 29, 2006 #1

    silence882

    silence882

    silence882

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    Hello all,

    I was wondering about the usefulness of geographic distribution as a factor for determining taxonomic boundaries.

    For example, to differentiate between Paph. appletonianum var. appletonianum and Paph. appletonianum var. hainanense. If not for var. hainanense occuring only on Hainan Island, I'm not sure these two taxa would warrant separation.

    --Stephen
     
  2. Nov 29, 2006 #2

    slippertalker

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    I think that it is useful to know the origin of species, and often seperation leads to specialization and new (related) species. Some species like lowii are spread over a very large area, and show a LOT of variation. Whether the two species you mention are worthy of seperation is up to the taxonomists, and they tend to have different opinions.

    I have grown both of these plants, and they appear to have some differences. P. appletonianum v. hainainense has more of a gloss to the flower and a bit more presence. There are a lot of populations of appletonianum that have been discussed as seperate species with slight differences, but at the end of the day are they different enough to justify their own epithet? It's obvious that they are all closely related.
     
  3. Nov 29, 2006 #3

    Rick

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    Distribution can be a very important factor if it leads to genetic isolation, and speciallization as Slippertalker put it.

    However, as Guido stated, morphometrics are the primary tool to separate taxa by taxonomists (nomenclaturist as per Victor Albert). Distribution data is often considered supporting data at best, since collection data may often be fraudulent.
     
  4. Nov 30, 2006 #4

    VAAlbert

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    Quick clarification, Rick:

    A 'nomenclaturalist' concerns himself with the validity of names. A taxonomist erects a system (= classification = taxonomy) based on these names. Most taxonomists are also practicing nomenclaturalists, although I know of at least one guy who basically only goes around validating improperly published names (not in orchids).

    Regarding geography, of course it is important for evolutionary research, and can be useful in taxonomy as an adjunct to morphological key characters. For example, if a friend of yours was in Oaxaca, Mexico and came across a slipper groing on a cliff-face in a remote dry wash, and he didn't tell you what it looked like, you are sure it is Mex and nothing else.

    Geography is obviously of importance when doing population level analyses, either genetic or morphometric.

    Best wishes,

    Vic
     
  5. Nov 30, 2006 #5

    Braem

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    Stephen et al,

    I fully agree with Victor. Geography CAN be useful but must be applied with caution and care.

    Guido
     
  6. Nov 30, 2006 #6

    Braem

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    And yes, the point that Rick makes is very important. The Code stipulates that you need to indicate a location. The Code does not stipulate that the given location must be the correct one, and we know that in many cases it is not.

    That was one of the point of validating Paph. crossii. The original publication is not to be considered invalid because it states that the type came from Peru.

    Guido
     

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