In Which, Despite Not Being The Crowd Favourite, Drosophila funebris Holds D. melanogaster Down and Kicks It Repeatedly in the Teeth

The original and still reigning champion, Drosophila funebris. Fear it, I say! Photo by Nicolas Gompel.

It's been two years in the making, but the ICZN decision on Drosophila has finally been announced (ICZN, 2010). You may recall that an application had been submitted (Linde et al., 2008) to make Drosophila melanogaster, the subject of countless genetic studies, the type species of the genus instead of the current holder of that title, D. funebris. See previous posts here and here for background details.

And the verdict: by a surprisingly large margin (23 to 4, with one absence), the Commission has turned the proposal down. Drosophila funebris remains the valid type species of the genus; D. melanogaster retains the potential for reclassification. Those of you with a particular interest in the workings of nomenclature* would do well to get hold of a copy of the decision. In light of the higher than usual public interest in this case, the unusual step has been taken of publishing individual comments from each of the commissioners on the reasoning behind their decisions. As well as the insight provided into this particular case (and it's worth noting that some of the commissioners on both sides of the floor ended up voting against their own initial sympathies), some of the comments provide interesting talking points about the role of nomenclature in general.

*Yes, we do exist. I'm afraid the doctors say that there's nothing they can do.

Some of the reasons given for voting against the proposal were reasonable, others less so. A. small number of commissioners voiced the complaint that the proposal was asking the ICZN to endorse a particular taxonomic method; as I argued in one of the previous posts, it did no such thing and I am rather disappointed that this issue was raised. Some commissioners also turned down the proposal on the grounds that it was premature (Miguel Alonso-Zarazaga stated that he "felt that the authors of the case had not allowed the community to have a healthy discussion of their proposals, since the ‘detailed phylogenetic studies’ mentioned in the case were still largely unpublished, and were thus hypothetical"). However, while the proposal may have been precipitated by an as-yet unpublished study, the results of that study are hardly novel. As pointed out by László Papp in his comments on his supporting vote, the issue that any subdivision of Drosophila would require the removal from that genus of D. melanogaster has been under discussion for at least 35 years (a time when, I should note, purely phylogenetic considerations were often considered less significant).

Less trivial are the concerns that the proposal introduced a higher overall nomenclatural instability than the current status quo and that it may have set an uncomfortable precedent. The commission was being asked to choose between maintaining Drosophila for a smaller number (about 300) of species including some very well-known taxa, or a potentially much larger number (up to about 1100) of mostly less familiar species. Should "celebrity names" carry that much greater weight? Also, while the combination Sophophora melanogaster may be unfamiliar, there is no actual ambiguity about to what it refers.

Some commissioners, as well as many of the ICZN's press statements, raised the argument that "drosophila" could still be used as an informal name for Sophophora melanogaster. True, as far as it goes, and not unprecedented: names such as "azalea" and "cosmos" continue to be used despite the genera of those names being stricken from the technical literature long ago. Nevertheless, this is not anywhere near a satisfactory solution. As a corollary example, a number of recent authors have proposed restricting "Aves" to the crown group of birds on not unreasonable grounds. The supposed divide between technical and vernacular names has done nothing to dissuade people from objecting to the idea that creatures such as Archaeopteryx and Ichthyornis may no longer be "birds".

My thanks go to Kim van der Linde (first author of the proposal) and Elinor Michel (secretary of the ICZN) for sending me copies of the decision. Kim's own reaction to the ruling can be read here.

REFERENCES

Linde, K. van der, G. Bächli, M. J. Toda, W.-X. Zhang, Y.-G. Hu & G. S. Spicer. 2007. Case 3407: Drosophila Fallén, 1832 (Insecta, Diptera): proposed conservation of usage. Bulletin of Zoological Nomenclature 64 (4).