Discussion in 'Codex taxinomiae plantarum (CTP)' started by VAAlbert, Feb 17, 2009.
It comes from a taxonomist, that's why you should believe it! :evil: oke:
The devil made me do it!
I do not think any serious taxonomist (sorry if I offend anybody here!) would use pollinators to support this...
LOL sorry, I also re-read my post and realized it was confusely written what I wanted to say is that taxonomy is based mainly on morphologiocal characters, and of course DNA evidence can be use as a support, however it is not the standard... Phylogenetics and molecular systematics are normally the ones using DNA evidence to support relationship between different taxas..
Oh, by all means YES. Indirectly that is. Most taxonomists these days are also phylogenetic systematists, so they name stuff based on relationships, and molecules (if chosen properly!) are a valuable tool in this field.
I respectfully disagree! Pollinator relationships and biogeography are totally in tune with taxonomy via the phylogenetic systematic route. They can be very useful characters in fact.
I agree, you should use all the tools available. That way you don't call a sport a species!
Oooo. I'm loving this.
Doc Robert: I personally think "splitting" at the species level is the way to go with orchids. Why? Because it will be reflected in the hybrid registration. This has a major impact on the HOBBY and ECONOMY of orchids. Consider Paph glaucophyllum and moquettianum. They breed VERY different. As a consumer, I like to understand the parentage of a cross I buy, and by now recognizing there two taxa at the species rank, I can get a load of info simply from the grex name. Prior to this recognition, you had to guess which version was used. Split away! At the higher levels, though, I sorta like the massive genus approach (ie a broad Cattleya genus versus Catts, Laelia, Schombrugkia, Sophronitis...).
Sorry, Ramon, not to pick on you, but again, I respectfully disaggree. Phylogenetic systematists use morphological, meristic, molecular, and biogeographical data. One is not precluded by the other.
Allopatric speciation is geographically-center notion of segregation into distinct entities; ecologically induced speciation can occur in near sympatry if different, closely-related organisms inhabit different niches within a biome. For example, species that form as forest-floor specialists versus light-gap/edge specialists. These specializations can involve different light, nutrient, and water regimes, not to mention different pollinator preferences.
Check out the PDF of my old paper on Mexipedium at its Wikipedia site (http://en.wikipedia.org/wiki/Mexipedium) -- Mark Chase and I used morphological characters and a supporting DNA-based phylogeny to segregate Mex from Phrag.
To understand the process a little, in a nutshell and the order is sometimes mixed a little, but...
A scientist is presented with a handful of taxa. He/she uses characters (morphology, mersitic, molecular, biogeographical...) to determine their relationships. From the relationships, taxonomy is derived (or changed). To help folks understand what defines the taxa, easy to see traits (morphology) are used to tell others a quick way to tell who is who. It's silly to tell someone that paph. rothschildianum differs from sanderianum by a huge segment of base changes between positions X and Y on gene Z when you can simply say "Sandy has long petals". So you never really "see" molecular data in taxonomic keys or diagnoses for practical purposes, but it has certainly pervaded the science.
I agree that pollinators and biogeography are generally in tune with taxonomy, however... there is strong evidence that Odontoglossum and Oncidium are different genus, that's where I say that the similar pollinator cannot be used as an important character to bring these two genera together again! and that's what I was talking about... on the other hand, as I said, I need to verify the source where I read that, because... welll we would start the discussion again
and I agree with you, but molecular systematic (and that was my sentence) use only molecular evidence...
The segment of bases can be very helpful for IDing out-of-bloom when the marker has been found to be consistent within an entity.
Such use of markers, or 'barcodes', should not be mistaken for a taxonomy -- consistent DNA markers only point you to an entity that has a particular nomenclatural status in a classification.
Ooooooh, my head is spinning!
To expound on this: The pollinator relationships and biogeography (both space and time) are critical to understanding the genetic isolation of a particular plant species.
As noted in the GH you can cross a huge array of orchid genera and produce viable offspring. Subsequently if taxonomy is based on visual characters and DNA you end up either generating gobs of new species or proving that the present (on paper) species boundaries are worthless.
What happens when a 'species' occupies a large geographical area and shows significant variation within that area? What criteria are sufficient to draw lines between varieties and species? Do these criteria vary depending on the species that is being considered?
For example, Paph. callosum can be found over a large area of mainland southeast Asia. It has a number of described varieties (some of which were described as distinct species) and overlaps with the habitat of Paph. barbatum. I think a convincing argument could be made that Paph. callosum and Paph. barbatum represent a single species with an extremely wide spectrum of variation. What criteria should be used to separate different species/varieties within this complex?
Widespread 'species' are a difficult issue -- for me, diagnosis is the key: if you can't provide a diagnostic characteristic to tell the difference between entities, then you have trouble grouping the entities under one name.
I'm with ya, but again, there is no cheap dipstick test that would enable the average Joe to say, "yep there's that marker, thus this is species A". So, when a multi-taxon diagnosis and dichotomous key is published, the author uses things we can see and touch. So I think the fact that molecules might have been used in the sciences gets lost.
Ah, a parsimony guy. I guess that means I can still talk to you. Any likelihood folks out there??? Just kidding, I think both have their utility when used properly. But if you don't know enough going in, parsimony is usually safer. (Can of worms, open up...)
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