[Taxacom] Read... and believe...

Bob Mesibov mesibov at southcom.com.au
Sun Sep 6 06:16:46 CDT 2009

I urge Taxacomers to read Roger Hyam's blog (http://www.hyam.net/blog/archives/598) in full, but here's an interesting chunk:

"Up to now the assumption has been that we are discovering taxa in nature and then attempting to describe them. It is undoubtedly true that taxa do exist in nature. However, in order to construct a usable map of biodiversity, we need to turn this on its head. It is the act of minting an identifier and linking it to a circumscription that creates the taxon. We then discover which specimens in the wild fit into this taxon. Philosophically this his how we act anyway (see Identifiers, Identity and Me). Taxa are currently hypotheses (things we invent) that may break down as our knowledge grows."

Much of the Taxacom discussion so far has been about species identification, because species identification is what barcoding promises. But Hyam says 'taxon'. Re-read the paragraph above substituting 'genus' or 'family' for 'taxon'. Still OK? (That is, if you thought the paragraph was OK when 'taxon' meant 'species'.) Note also that barcodes could also theoretically be used to predefine taxa higher than species, by relaxing the sequence requirements in ways indicated by species sampling within the higher taxon.

Now, what strikes me as strange and wonderful is that OTTH I'm perfectly happy with Hyam's approach when thinking about genera and families, which are constructs with a lower-grade 'existence in nature' than species. In fact, this is how I think genera and families get built into classifications, traditionally. It's certainly how I go about erecting new genera for my beloved millipedes

But OTOH, Hyam's approach just doesn't click with me when I think about circumscribing new species. Not already recognised species, of the kind we identify a la the Taxacom discussion, but previously unrecognised species. Like, most of the world's species?

If I read Hyam correctly, his circumscription of new species, just like that of old species, is by means of a barcode. Quick, simple and unambiguous (caveats, caveats), this approach *replaces* morphospecies with barcodes. The option of linking Hyam's Barcode Taxa to morphospecies data (with keys, diagnoses, images, etc) is just that, an option - to create 'secondary taxonomic products' (Hyam's phrase) or not.

So you could produce a 'map of biodiversity' by barcoding madly on a field trip and recognising - excuse me, defining - heaps of new species. Think of that as step 1. Steps 2, 3, etc would be learning the answers to questions like 'How big is it?', 'What life stage?', 'Male or female?', 'Associated with what [plant/animal]?'. Lotta work there, but that would certainly make the 'map of biodiversity' more usable. Take biological control, for example. Don't know how far I could get with 'GenBank RQ561336 a possible parasite of GenBank AE699133', but it would be a real comfort to know that these entities had been rigorously circumscribed right from the beginning. Yessir, very comforting.
Dr Robert Mesibov
Honorary Research Associate
Queen Victoria Museum and Art Gallery, and
School of Zoology, University of Tasmania
Home contact: PO Box 101, Penguin, Tasmania, Australia 7316
(03) 64371195; 61 3 64371195
Website: http://www.qvmag.tas.gov.au/mesibov.html

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