Field of Science

What are the Bare Necessities?







Let's move on to the details of Dayrat's recommendations:













  1. What about non-systematic research on unidentifiable species? Unidentifiable because the systematics is known to be woefully incomplete. At the minimum, voucher specimens should be deposited so that the identity of the species can be determined later. But what name should it go by?

    For example, I study the Evaniid wasps. I have a series of 40 or so species from one trap in Ecuador that are unidentifiable, and likely 50% or more are new species. If I wanted to write a paper about the local species diversity, should I avoid names? That would mean that voucher specimens could never be integrated into collections until some later paper published their identities. Whereas if I gave them names (some, doubtless synonyms) with vestigial descriptions or photopgraphs, they could be integrated into collections and thus easily available to systematists for taxonomic study.

  2. Mike, I'm inferring from your comment that you're not actually planning on doing the systematics yourself, but you are sorting to morphospecies. I'm currently working alongside people conducting ecological surveys that are also coming back 90% undescribed species, so I can sympathise with your dilemma.

    Most collections will take, and can probably access*, unidentified specimens, though it would be more helpful to everyone if they can be identified as far as possible. I'd guess that at least 95% of every museum's collection is unidentified. Unless you're planning on doing a formal description, it would be far better if you didn't give your morphospecies actual names, because that would probably do more harm than good when someone came to do the full taxonomic revision (the nomen nudum is an evil thing). My advice would be to voucher all of your morphospecies. At least a sequential number that's included with the specimen label when you hand your specimens to a collection. Even better (if you were publishing your results) would be to get accession numbers for your specimens from the collection (e.g. AMNH 6132 would be the 6132nd specimen registered at the American Museum of Natural History) and refer to the morphospecies using the accession number as the voucher number (e.g. Evania sp. AMNH6132, were there such a thing).

    *The limiting factor in registering specimens in museum collections and such isn't usually identification, it's the availability of someone to actually enter the specimen data into the records or database.

  3. There are certainly better ways to do taxonomy. Naming an animal based on fragmentary remains doesn't happen so much anymore, but the anals of paleontology are clogged with quickly-named genera and species which can probably be reassigned or can't be assigned at all. Did you know that pachycephalosaurs were originally thought to belong to Troodon because of similarities in the teeth? The first big review of the pachycephalosaurs is called "A Review of the Troodontidae." In it, Pachycephalosaurus is described!

    At any rate, I think that museum collections are sorely ignored. You can find just as many (if not more) species in the basement these days than in the field.

  4. Zach, I'm not denying the presence of nomina dubia, though some groups of organisms are more afflicted than others. My point is that there's no way of a priori establishing whether a given taxon is dubious or not. I was aware of the Pachycephalosaurus-Troodon connection. On the flip side, consider the two Dinornis species recognised by ancient DNA studies that are osteologically identical (as far as I know). In this case, no degree of completeness of the skeleton is going to identify the species if molecular data is unavailable.

    As Valdecasas et al. note, we will always have bad taxonomists with us. My feeling is that by setting the bar so unrealistically high, Dayrat actually ends up favouring bad taxonomists who simply ignore the guidelines rather than good taxonomists who refrain from publishing because they cannot fulfil all the requirements with the material available. Also, as I said, Dayrat's recommendations effectively discourage research on poorly known groups, systematic work on which must necessarily start falteringly.

    I certainly agree with your comments on museum collections - I'm currently working entirely from pre-collected specimens myself. To a large extent, it depends on exactly what your requirements are for whatever study you're conducting.

  5. "The anals of paleontology..." *snicker*

    That "Troodon" reconstruction has an terribly dromaeosaurid skull.... Should you ever need another troodontid illustration feel free to use mine (of a soon-to-be-described, early troodontid).

    Personally, I find the assertion of Troodon formosus as a valid name a bit bizarre, when most other non-mammalian tooth taxa are considered dubious. Bring back Stenonychosaurus inequalis!

    Anyway, interesting stuff. This is why I usually try to stay out of alpha taxonomy. :)

  6. Again, as I understand it the "validity" of Troodon is directly contingent on the absence of any other contender's for the holotype's identity from the type locality. The possibility always exists that said contender could turn up tomorrow, but until that day comes I feel it's better to try and make sense of what we have on hand.

    Of course, the ICZN always exists as a dealbreaker if things get too messy, as happened for Coelophysis. Mind you, the Coelophysis decision was a fairly unusual one, and I don't know that Troodon has the following that Coelophysis does.

    My experience is that when faced with a potential nomen dubium, authors generally take one of two options. One - the 'Gordian knot' approach - is to treat the nomen dubium as an effectively invalid name and more or less ignore it. The other - the 'port in a storm' approach - is to go to whatever measure is necessary to attach the name to some available taxon. I must confess to favouring the second approach where possible - I feel that the first approach leads to an excess of taxa. Those nomina dubia are still valid names, and will still be around to haunt future researchers. But then, I work with recent taxa for which the chance of resolving dubious names satisfactorily (for instance, by going out and collecting more specimens from the type locality) is often much higher than with fossil taxa. The problem with the 'port in a storm' approach, of course, is that then the poor condition of the holotype becomes a lounge-pachyderm that could always cause everyone grief later.

  7. Oops, I was going to add: Again, I feel that selecting the appropriate response to any individual nomen dubium should probably be left to the judgement of the researcher working on the specimens.

  8. These are interesting issues. I read Benoit Dayrat's paper a couple of years ago & had more or less the same objections to his suggestions that are raised here. I have also listened to his talks at the American Malacological Society Meetings. If I am not mistaken, some of his suggestions tie in with the Phylocode rules.

  9. Aydin, exactly the point I was going to make...

    Chris, great work on this post. I mostly agree with you so I won't comment too much.

    One of the groups I work on are anemones. There is absolutely no way to preserve them for histology than by 30% formalin. Ethanol is out of the questions and low concentrations of formalin do not adequately penetrate the tissue fast enough. The result being an unidentifiable specimen (anemones are ID'd based on histological characters). Dayrat's preservation protocol would destroy my samples. If anyone has ever tried to ID and describe a bag a goo, then they would understand.

    I also attach names to everything, sometimes because I'm a little overconfident, but if I have any doubt I refer to it as aff.. If I think its new then Family sp. or Genus sp. Its both how I was trained and what makes sense to me and makes everything easier to catalogue and sort.

    I view DNA and barcoding as complementary to alpha taxonomy, which is the grunt, kind of like assigning the operational taxonomic that the molecular phylogeny will then use and compare with other OTUs to answer larger evolutionary/systematic questions. That is why I try to include phylogenies with descriptions whenever possible. Even if it is only a single gene, like COI, it makes taxonomy more scientific and relevant. Of course I can't do this all the time...


Markup Key:
- <b>bold</b> = bold
- <i>italic</i> = italic