Re: The Dark Side of Taxonomy, part II: The Empire Strikes Back!

From: John Grimshaw <john.grimshaw at zoology.oxford.ac.uk> on 1996.12.29 at 17:32:26(22) I am glad to see that the devil's advocacy approach that I took had the desired result of eliciting the reasoning for the proposed sinking of Sauromatum into Typhonium. Now (and particularly when the paper appears), we have information on which to base our own views, without having to accept the blunt and rather dogmatic statement with which we were originally presented. On this evidence, the decision by Wilbert and Peter Boyce to sink Sauromatum does indeed seem logical, and I can support it when presented in these terms. Nobody else need do so, but you must come up with equally valid reasons for maintaining them as separate genera, when the two competing schemes would be assessed on their relative merits by practising taxonomists. Wilbert emphasises similarities and not differences in determining phylogenies. Here, again, is a point where personal decisions come into play. At what point do derived differences differentiate between taxa? That there are DIFFERENCES between similar entities is the fundamental basis of taxonomy; similarities are, of course, essential to detect phyletic pathways in a group of organisms, but eventually it is the differences that define the subsidiary taxa. In the situation under discussion the question is, 'Has Sauromatum (perhaps only S. venosum) sufficient differences (of whatever character) to be maintained as a distinct genus, or are the differences slighter than the similarities, justifying its inclusion in Typhonium?' Wilbert and Peter choose the latter: can anyone else do better? If the evidence (morphological and molecular - and I can assure Wilbert that I am very well aware of the dangers and uses of molecular taxonomy) is so strongly in favour of the sinking, then it is surely wrong and inconsistent to propose Sauromatum venosum as a name for conservation. If it IS a Typhonium it MUST be called a Typhonium - to have a stray Not-really-Sauromatum (Ought-to-be Typhonium) situation is poor science and serves neither horticulture nor botany. If a change in specific name was required because (e.g.) an obscure synonym was discovered to have priority, then there would be valid grounds for conservation of the widely known name, but to knowingly conserve and perpetuate an incorrect genus should not be acceptable. John Grimshaw +More PS My e-mail account is due to be axed in a few days time: my silence should not be taken otherwise! On Tue, 24 Dec 1996, NAME Wilbert Hetterscheid wrote: > Aroidellers, > > I am glad that the Sauromatum case provoked several reactions, > some of which made me blush. I'll first enter the debate with > John Grimshaw and I am afraid it may contain some X-rated > terminology but I need that to answer him: > > To John then: > > Three genera - indeed a cladogram (the graph) as presented by > me could also be cut up in three genera. The result would be > that Sauromatum keeps it's name, several Typhonium species > have to be renamed in a new genus and the "old" Typhonium gets > changed and loses several species. I would call that taxonomic > instability. Maybe the users of Sauromatum will be pleased but > Aroid taxonomists will scratch behind their ears and think > that I was making a mess of it just to have the fun (?honour) > of creating a new genus. By creating a new genus I would still > not make clear the relation between Sauromatum and Typhonium. > The three genera solution only splits up Typhonium. I call > that less than desirable from a scientific point of view. The > cutting of the cladogram in three genera is much less > phylogenetically informative than sinking Sauromatum. And a > phylogeneticist, as I am, should try to elucidate relation- > ships not disguise them. > > the evidence - it is morphological and if you have a problem > with that in comparison with molecules, let me tell you that > the interpretation of molecular data for phylogentic models is > FAR from settled yet. Molecules do NOT hold THE evolutionary > information some molecular systematists like to believe. It is > an important part of phylogeny reconstruction but also a hype > at the moment that yields funds and I get suspicious when > suddenly such an angle of inquiry gets so much attention. > Let's first get the methodology right and THEN do millions of > analyses. O.k. back to morphology then: I am not going to > rewrite the whole manuscript here but the main difference > between Sauromatum and Typhonium that is still in use (see > Sriboonma et al. 1994) is the fact that Sauromatum develops > its leaves AFTER flowering! To begin with, this character does > NOT hold true for S. brevipes, so that's that. Second, many > Typhoniums (notably the pedatisect-leafed species!) flower > when the leaf is still very underdeveloped. The situation in > S. venosum could be seen as just a minor step further towards > flowering before leafing. In the scheme of knowledge of > Araceae this distinction is totally inadequate to found a > generic separation on. Another character used to distinguish > Sauromatum is the connate spathe base versus convolute in > Typhonium. Alas, T. hirsutum has closed and convolute spathe > bases. On top of that in Araceae genera this distinction is > not unknown. In Amorphophallus e.g. there are two species with > connate spathe bases too and I would not create a new genus > for them. > > Now the philosophical point to be made here is that > "differences do not a phylogeny make", a basic adage of phylo- > geny reconstruction. It doesn't matter HOW much a species > differs from others! The SIMILARITIES decide where it belongs! > So I am NOT primarily interested in the DIFFERENCES between > Sauromatum and Typhonium, but the SIMILARITIES and they are > MANY! For those who have T. giganteum and S. venosum: compare > the internal structures of both when they flower and you'll > see the remarkable similarities. In fact Sauromatum has MUCH > more similarities with Typhonium than differences. THAT is why > Peter and I thought that both Sauromatum species had to be > analysed together with Typhonium species to see if they would > come out as a sister genus, or as a nested set IN Typhonium. > The latter happened. > > In the phylogentic amalysis is showed that withing Typhonium > the character of having a pedatisect leaf comes out as an > evolutionary derived character (so called "apomorphy") and > thus defines an evolutionary independent group (monophyletic > group) IN Typhonium and..............both Sauromatum species > are nested IN that group. They then come out close to T. > hirsutum on the basis of the connate spathe base. So, all in > all, both Sauromatum species evolved FROM bonafide Typhonium > species and thus ARE Typhonium species themselves, be it with > their own shared characters that were once looked upon as SO > odd that they merit generic recognition. The result of that > move was that Sauromatum fell outside Typhonium and was thus > wrongly classified in an evolutionary sense and as a result > Typhonium was crippled because it lost TWO of its members. > That means that if I were to create an evolutionary scenario > for Typhonium, I would always be incomplete for lack of dis- > cussing the two species that are Sauromatum. Typhonium then > becomes a paraphyletic genus, and we wouldn't want that. > > Rotating in a cladogram: .......has NO influence on the resul- > ting classification. If I had rotated the way you propose, > both Sauromatum species would still have the same ancestry in > Typhonium. They would still be nested. There is no way you > could read a cladogram in terms of "percentage of morphologi- > cal divergence". That is NOT what a cladogram is about. And, > like I said before, I don't care how much Sauromatum is diver- > ged, it still has its ancestry IN Typhonium and NOT outside > it. It would be totally illogical to change ancestry on the > basis of divergence. Those two have NO relation with each > other. > > To help gardeners and interested people, I proposed that the > name Sauromatum venosum could be conserved. It could also be > horticulturally stabilised by apllying for addition to the > ISTA list I mentioned before. > > To Larry: > > The fact that your interspecific Iris hybrids have no name is > only logical. Here is a subject that I am VERY involved with. > Taxonomists may give hybrid names when they detect hybrids in > nature. Some of us think that is superfluous as we don't know > how ephemeral the hybrid is but others disagree. In cultivati- > on however, hybridisation is the major breeding method and > millions are made over the whole world. Should we all give > them a Latin hybrid name? It has happened in Saxifraga! I hope > saxofrage enthusiasts enjoy the dozens of Latin names for > material that basically consists of cultivars! I find it > absolutely horrendous. And remember that all those hybrid > species names HAVE TO FOLLOW ALL RULES OF THE BOTANICAL CODE!! > Now THERE is a source of instability in horticulture that we > could well do without! The Cultivated Plant Code gives a good > tool to group cultivars that look alike into a very stable > system, that is NOT influenced by the Botanical Code. These > are called cultivar-groups. In Iris, several are already > available: Iris Germanica Group, Iris Hollandica Group etc. > > Orchids is a case in point. The insanity of creating so called > Grexes for EVERY cross that occurs in cultivation has reached > momentous proportions. Then there are the artificial hybrid > genera in orchids that are created more and more. We are > thinking of stabilising that system by grouping genera of > orchids and saying that every cross between genera in that > group get ONE and the same hybrid genus name. That should put > an end to the name game in orchids. In the latest Cultivated > Plant Code (1995), the grexes have already been banned to a > mere note. > > To Steve: > > We agree Steve but don't let Dendranthema keep you away from > using "chrysanthemum" as a common name! THAT hasn't changed! > > The cult of cultonomy is doing o.k. as could be expected of a > new concept in a primarily conservative field of taxonomy. > Some papers have already been issued using it. I guess that > the big test will be the Symposium on Cultivated Plant taxono- > my in 1998 in Edinburgh. I am sure it will be a topic there. > > To Ray: > > You should see how often I meet with the name "Arum cornutum" > in the bulb-trade these days. Steve the other day was glad > that name was gone but I am afraid it STILL isn't. And in the > meantime taxonomists is a dying race................ > > Cheers to you all, > Wilbert >  > >

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