Bortolus, A. 2008. Error cascades in the biological sciences: the unwanted consequences of using bad taxonomy in ecology. Ambio 37 (2): 114-118.
As you may have guessed from the title of this post, I'm kind of pissed. I got forwarded a copy of this paper earlier today, and was horrified by the results presented in it. Bortolus presents the results of a paper survey of 80 ecological papers published from 2005 to 2007 in ten top-ranked peer-reviewed ecology journals. The subjects of this survey were community ecology studies dealing with more than one species of organism, and for each study Bortolus took note of the sources for the identifications of the taxa surveyed. I hardly need point out how significant such identifications would be for the papers in question - after all, if the subjects of an ecological study are not reliably identified then the usefulness and significance of the entire study comes into question. So you would think that it would be pretty important for the authors to demonstrate the firmness of their identifications, no? Well, let me show you the graph of the results:
Note that the numbers do not necessarily add up to 100%. A single paper might haved used more than one form of identification. I also disagree slightly with Bortolus' treatment of "grey" (not or not significantly peer-reviewed) literature - lumping the citation of field guides in with unpublished theses does somewhat overlook that excellent field guides do exist for some taxa (most notably birds), and even amateurs without formal taxonomic experience may through these field guides hold a significant amount of expertise in identifying the taxa covered (also, of course, field guides are widely available and consultable while theses are not). Nevertheless, let me point out the part of the results that has incensed me the most. It's the second bar from the left. Fully a third of the papers surveyed gave no authority whatsoever for the identity of the species surveyed! It's not as if the bar was set particularly high for citing an authority, either. Acknowledging the input of a taxonomist who identified specimens (or having a taxonomist as one of the authors) counted. Noting that one of the authors of the paper had personally identified the taxa counted, or the use of a cited identification key, counted. All it would have taken in most cases would have been a couple of sentences. And yet, it seems that this is a couple of sentences too many in a lot of cases.
Of course, the availability of voucher specimens would do a lot to alleviate these concerns. I've written before about the importance of voucher specimens that allow other researchers to check specimen identifications. so how many of the papers surveyed noted the availability of voucher specimens?
Yes, you read right. Two point fricking five percent. What is more, those papers that did record voucher specimens were invariably among those that acknowledged the input of a professional taxonomist in some way, and so were probably not among the more suspect class in the first place.
As is de rigeur in this kind of discussion, Bortolus gives us examples of the kind of errors that can result from poor taxonomic practice. Some errors are fairly innocuous, but others can have fairly serious consequences. There's the case of a restoration programme in San Francisco that included the propagation and replanting of the native littoral grass Spartina foliosa. Unfortunately, the actual specimens propagated were not S. foliosa, but the non-native S. densiflora, and as a result of the programme S. densiflora was transformed from a minor adventive to a significant invasive. There's the case of three morphologically similar but ecologically distinct Mytilus mussel species, the decline of one of which due to the invasive spread of another went unnoticed for many years. There's the case of a failure to distinguish Anopheles mosquito species in Burma resulting in the long-term targeting of a non-malaria-carrying species by control programmes instead of the actual malaria vector. Bad taxonomy does matter.
Some of my readers may protest that it seems a little harsh to expect identification sources from authors who may be very familiar with the species involved and hence might be trusted to identify them reliably. To which I reply, bullshit. One of the main principles of science is that it is not enough to simply assert that one "just knows". And besides, is it really asking that much? Biomolecular studies, for instance, are expected to include full details of methods used, and it would not be considered unusual for an author to cite Saiki et al. (1988), no matter how many thousands of PCR reactions that author might have conducted during their career. Also, there are significant ethical considerations involved. In failing to cite or acknowledge their identification sources, authors are doing a significant disservice to the taxonomists on whose work their own relies. It is exactly this assumption that the reliability of taxon identifications can be taken for granted that has resulted in the undervaluing and loss of taxonomic expertise in many parts of the world. Is a passing mention in the acknowledgements really that much to ask?
Why I'm Marching for Science
20 hours ago in Angry by Choice