Bad Science?

Under sweeping new rules, botanists have made their first formal plant species identification solely through DNA sequencing. Prior to January 1, new plants had to be described by their visual characteristics in Latin. There are no Latin words to describe DNA results, so the technology could not be fully applied. But now, Latin is no longer required so the door is open to a faster and more efficient way to identify new species.’ A statement on the website Planet Ark.
For some groups, such as yeasts, DNA sequencing is proving useful for establishing new species. It has also helped discover cryptic species amongst the birds. However, some botanists have pointed out that point 32.2. of the code states that to be validly published a new name must have ‘a diagnosis’ which is a statement on how this new taxon is distinguished from others. In the past this has implied a morphological description. Unfortunately, point 32.2 is vague enough to probably allow just the comparison of DNA sequence data.
One of the disturbing things about modern classificatory paradigms is that a whole level of organization (organismal morphology) is being written off as scientifically worthless. Am I the only one who is scared by the implications of this?
I personally think this is bad science. Biodiversity presents us with information at the molecular, the genetic, the organismal and ecological level – and data from all level gives us important information about how organisms manifest and change with time. The acceptance of strict monophyly is allowing scientists to discount groups of organisms defined by unique morphologies. These groups are valid and could easily be accepted under a paraphyletic classification. This is possibly arguable, but if we are to create classifications in which data from all levels of organisation are acknowledged for the value that is inherent in them, then we must accept paraphyly. Besides all new major evolutionary lines start off as paraphyletic side branches -- and paraphyly says a great deal about the way in which organisms evolve.
Hopefully, in time, taxonomy will become somewhat rational on this matter and acknowledge that we need to take cognisance of the data we obtain from all levels of reality. If we accept this then, certainly for multicellular plants, I think any diagnosis based on molecules should also be accompanied by morphological descriptions. We will have to see if the code in future takes note of this or not. My faith in the code ended abruptly last year.
Fortunately, I think there are many taxonomists out there that feel the same way.
Ashley Nicholas, University of KwaZulu-Natal (via Plant-chat@yahoogroups.com)