Saturday, November 5, 2011

Attack of the Phylogeneticists!

Ceci n'est pas une Ondontoglossum
If you own any Odontoglossums it's time to change the tag. Molecular phylogeneticists have, once more, unleashed their cladograms on the orchid community. New DNA studies show that Odontoglossums are not meaningfully distinct from Oncidiums in terms of genetics and evolution. The Royal Horticultural Society (RHC) has decreed that Odontoglossums are now Oncidiums. The RHC creates the official taxonomical reality for the American orchid world (institutionalized in the American Orchid Society). So, we now change our tags from Ond. to Onc. No big deal, right?

But what if you're, say, Robert Hamilton, a founding member of the International Ondontoglossum Alliance? What if you've been obsessed with Odonts since 1979? The change might irritate you a little bit. 

Hamilton's article in the new issue of Orchid Digest "Odonotoglossum: Requiescat in Pace" traces the genus's history from its first description in 1816 to its recent demise. Hamilton acknowledges phylogenetics as "valid science," but raises three concerns. The lumping and splitting required of any taxonomical distinction, whether its based on DNA or not, is, ultimately, arbitrary. The DNA relationships ("clades") proposed by the phylogeneticists can result in infinite regress, such that the distinction between humans and chimps (Homo and Pan) falls away. Finally, the decision to lump Odontoglossum into the genus Oncidium fails the "five-year-old test" wherein a child can point to obvious differences between two flowers.

The "DNA Boys" (as Patricia Harding has referred to them) have prompted the orchid community to endure a lot of nomenclature changes in the last 10 or so years, and these changes have generate a lot of unbridled hatred toward taxonomists. But is it warranted?

I received poor marks in school for science and math, but I've seen the movie "Real Genius" enough to feel qualified to comment boldly on scientific disputes. The plot of Martha Coolidge's hit 1985 comedy suggests that you should side with the kids, in this case, the DNA Kids and their Crazy Cladograms. The phylogeneticists aren't setting out to ruin our favorite hobby. They proceed from the simple fact that some orchid species evolved before other orchid species. Discovering and analyzing patterns among those evolutionary relationships might, in the long run, help us grow better and healthier orchids.     



   

1 comment:

The Sage Butterfly said...

It is always confusing when those scientists decide to change something, but I know it is most likely to correct something or make it more clear.